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Sample records for fermi liquid behavior

  1. Landau's quasiparticle mapping: Fermi liquid approach and Luttinger liquid behavior.

    PubMed

    Heidbrink, Caspar P; Uhrig, Götz S

    2002-04-01

    A continuous unitary transformation is introduced which realizes Landau's mapping of the elementary excitations (quasiparticles) of an interacting Fermi liquid system to those of the system without interaction. The conservation of the number of quasiparticles is important. The transformation is performed numerically for a one-dimensional system, i.e., the worst case for a Fermi liquid approach. Yet evidence for Luttinger liquid behavior is found. Such an approach may open a route to a unified description of Fermi and Luttinger liquids on all energy scales.

  2. Magnetic moments and non-Fermi-liquid behavior in quasicrystals

    NASA Astrophysics Data System (ADS)

    Andrade, Eric

    Motivated by the intrinsic non-Fermi-liquid behavior observed in the heavy-fermion quasicrystal Au51Al34Yb15, we study the low-temperature behavior of dilute magnetic impurities placed in metallic quasicrystals. We find that a large fraction of the magnetic moments are not quenched down to very low temperatures, leading to a power-law distribution of Kondo temperatures, accompanied by a non-Fermi-liquid behavior, in a remarkable similarity to the Kondo-disorder scenario found in disordered heavy-fermion metals. This work was supported by FAPESP (Brazil) Grant No. 2013/00681-8.

  3. Non-Fermi liquid behavior from dynamical effects of impurity scattering in correlated Fermi liquids

    NASA Astrophysics Data System (ADS)

    Pramod, Kumar; Vidhyadhiraja, N. S.

    2014-03-01

    The interplay of disorder and interactions is a subject of perennial interest. In this work, we have investigated the effect of disorder due to chemical substitution on the dynamics and transport properties of correlated Fermi liquids. A low frequency analysis in the concentrated and dilute limits shows that the dynamical local potentials arising through disorder averaging generate a linear (in frequency) term in the scattering rate. Such non-Fermi liquid behavior (nFL) is investigated in detail for Kondo hole substitution in heavy fermions within dynamical mean field theory. We find closed form expressions for the dependence of the static and linear terms in the scattering rate on substitutional disorder and model parameters. We argue that the low temperature resistivity will acquire a linear in temperature term, and show that the Drude peak structure in the optical conductivity will disappear beyond a certain disorder pc, that marks the crossover from lattice coherent to single-impurity behavior. A full numerical solution of the dynamical mean field theory equations reveals that the nFL term will show up significantly only in certain regimes, although it is present for any non-zero disorder concentration in principle. DST India and CSIR India.

  4. Annealing, lattice disorder and non-Fermi liquid behavior in UCu4Pd

    SciTech Connect

    Booth, C.H.; Scheidt, E.-W.; Killer, U.; Weber, A.; Kehrein, S.

    2002-07-30

    The magnetic and electronic properties of non-Fermi liquid UCu{sub 4Pd} depend on annealing conditions. Local structural changes due to this annealing are reported from UL{sub III}- and Pd K-edge x-ray absorption fine-structure measurements. In particular, annealing decreases the fraction of Pd atoms on nominally Cu 16e sites and the U-Cu pair-distance distribution width. This study provides quantitative information on the amount of disorder in UCu{sub 4Pd} and allows an assessment of its possible importance to the observed non-Fermi liquid behavior.

  5. Disorder-driven non-Fermi-liquid behavior in CeRhRuSi{sub 2}

    SciTech Connect

    Liu, Chia-Ying; MacLaughlin, D. E.; Castro Neto, A. H.; Lukefahr, H. G.; Thompson, J. D.; Sarrao, J. L.; Fisk, Z.

    2000-01-01

    We report measurements of the bulk magnetic susceptibility and {sup 29}Si nuclear magnetic resonance (NMR) linewidth in the heavy-fermion alloy CeRhRuSi{sub 2}. The linewidth increases rapidly with decreasing temperature and reaches large values at low temperatures, which strongly suggests the wide distributions of local susceptibilities {chi}{sub j} obtained in disorder-driven theories of non-Fermi-liquid (NFL) behavior. The NMR linewidths agree well with distribution functions P({chi}) which fit bulk susceptibility and specific-heat data. The apparent return to Fermi-liquid behavior observed below 1 K is manifested in the vanishing of P({chi}) as {chi}{yields}{infinity}, indicating the absence of strong magnetic response at low energies. Our results point out the need for an extension of some current theories of disorder-driven NFL behavior in order to incorporate this low-temperature crossover. (c) 2000 The American Physical Society.

  6. Non-Fermi liquid behavior of the drag and diffusion coefficients in QED plasma

    SciTech Connect

    Sarkar, Sreemoyee; Dutt-Mazumder, Abhee K.

    2011-11-01

    We calculate the drag and diffusion coefficients in low temperature QED plasma and go beyond the leading order approximation. The non-Fermi-liquid behavior of these coefficients are clearly revealed. We observe that the subleading contributions due to the exchange of soft transverse photon in both cases are larger than the leading order terms coming from the longitudinal sector. The results are presented in closed form at zero and low temperature.

  7. Criterion for stability of Goldstone modes and Fermi liquid behavior in a metal with broken symmetry

    PubMed Central

    Watanabe, Haruki; Vishwanath, Ashvin

    2014-01-01

    There are few general physical principles that protect the low-energy excitations of a quantum phase. Of these, Goldstone’s theorem and Landau–Fermi liquid theory are the most relevant to solids. We investigate the stability of the resulting gapless excitations—Nambu–Goldstone bosons (NGBs) and Landau quasiparticles—when coupled to one another, which is of direct relevance to metals with a broken continuous symmetry. Typically, the coupling between NGBs and Landau quasiparticles vanishes at low energies, leaving the gapless modes unaffected. If, however, the low-energy coupling is nonvanishing, non-Fermi liquid behavior and overdamped bosons are expected. Here we prove a general criterion that specifies when the coupling is nonvanishing. It is satisfied by the case of a nematic Fermi fluid, consistent with earlier microscopic calculations. In addition, the criterion identifies a new kind of symmetry breaking—of magnetic translations—where nonvanishing couplings should arise, opening a previously unidentified route to realizing non-Fermi liquid phases. PMID:25349386

  8. Non-Fermi-liquid behavior in the fluctuating gap model: From the pole to a zero of the Green's function

    SciTech Connect

    Kuchinskii, E. Z.; Sadovskii, M. V.

    2006-09-15

    We analyze the non-Fermi-liquid (NFL) behavior of the fluctuating gap model (FGM) of pseudogap behavior in both one and two dimensions. A detailed discussion of quasiparticle renormalization (Z-factor) is given, demonstrating a kind of marginal Fermi-liquid or Luttinger-liquid behavior and topological stability of the bare Fermi surface (the Luttinger theorem). In the two-dimensional case, we discuss the effective picture of the Fermi surface destruction both in the hot spot model of dielectric (AFM, CDW) pseudogap fluctuations and for the qualitatively different case of superconducting d-wave fluctuations, reflecting the NFL spectral density behavior and similar to that observed in ARPES experiments on copper oxides.

  9. Non Fermi Liquid behavior and disorder in BaVS3

    NASA Astrophysics Data System (ADS)

    Akrap, Ana; Barisic, Neven; Rullier-Albenque, Florence; Berger, Helmuth; Forro, Laszlo

    2009-03-01

    In strongly correlated BaVS3, the interplay between a wide one-dimensional dz^2 band and the localized eg electrons leads to a wealth of electronic phases. In this work we investigate the high pressure non-Fermi liquid (NFL) phase of BaVS3 by means of transport measurements, focusing on the influence of disorder, introduced by fast electron irradiation and sulfur deficiency. Our results are interpreted within a novel scenario in which quasi-one dimensional 2kF-CDW fluctuations are responsible for the NFL behavior.ootnotetextN. Barisi'c et al., arXiv:0712.3393v1

  10. Tuning bad metal and non-Fermi liquid behavior in a Mott material: Rare-earth nickelate thin films.

    PubMed

    Mikheev, Evgeny; Hauser, Adam J; Himmetoglu, Burak; Moreno, Nelson E; Janotti, Anderson; Van de Walle, Chris G; Stemmer, Susanne

    2015-11-01

    Resistances that exceed the Mott-Ioffe-Regel limit (known as bad metal behavior) and non-Fermi liquid behavior are ubiquitous features of the normal state of many strongly correlated materials. We establish the conditions that lead to bad metal and non-Fermi liquid phases in NdNiO3, which exhibits a prototype bandwidth-controlled metal-insulator transition. We show that resistance saturation is determined by the magnitude of Ni eg orbital splitting, which can be tuned by strain in epitaxial films, causing the appearance of bad metal behavior under certain conditions. The results shed light on the nature of a crossover to a non-Fermi liquid metal phase and provide a predictive criterion for Anderson localization. They elucidate a seemingly complex phase behavior as a function of film strain and confinement and provide guidelines for orbital engineering and novel devices. PMID:26601140

  11. Tuning bad metal and non-Fermi liquid behavior in a Mott material: Rare-earth nickelate thin films

    PubMed Central

    Mikheev, Evgeny; Hauser, Adam J.; Himmetoglu, Burak; Moreno, Nelson E.; Janotti, Anderson; Van de Walle, Chris G.; Stemmer, Susanne

    2015-01-01

    Resistances that exceed the Mott-Ioffe-Regel limit (known as bad metal behavior) and non-Fermi liquid behavior are ubiquitous features of the normal state of many strongly correlated materials. We establish the conditions that lead to bad metal and non-Fermi liquid phases in NdNiO3, which exhibits a prototype bandwidth-controlled metal-insulator transition. We show that resistance saturation is determined by the magnitude of Ni eg orbital splitting, which can be tuned by strain in epitaxial films, causing the appearance of bad metal behavior under certain conditions. The results shed light on the nature of a crossover to a non-Fermi liquid metal phase and provide a predictive criterion for Anderson localization. They elucidate a seemingly complex phase behavior as a function of film strain and confinement and provide guidelines for orbital engineering and novel devices. PMID:26601140

  12. Tuning bad metal and non-Fermi liquid behavior in a Mott material: Rare-earth nickelate thin films.

    PubMed

    Mikheev, Evgeny; Hauser, Adam J; Himmetoglu, Burak; Moreno, Nelson E; Janotti, Anderson; Van de Walle, Chris G; Stemmer, Susanne

    2015-11-01

    Resistances that exceed the Mott-Ioffe-Regel limit (known as bad metal behavior) and non-Fermi liquid behavior are ubiquitous features of the normal state of many strongly correlated materials. We establish the conditions that lead to bad metal and non-Fermi liquid phases in NdNiO3, which exhibits a prototype bandwidth-controlled metal-insulator transition. We show that resistance saturation is determined by the magnitude of Ni eg orbital splitting, which can be tuned by strain in epitaxial films, causing the appearance of bad metal behavior under certain conditions. The results shed light on the nature of a crossover to a non-Fermi liquid metal phase and provide a predictive criterion for Anderson localization. They elucidate a seemingly complex phase behavior as a function of film strain and confinement and provide guidelines for orbital engineering and novel devices.

  13. Quantum phase transition and Fermi liquid behavior in Pd1 -xNix nanoalloys

    NASA Astrophysics Data System (ADS)

    Swain, P.; Srivastava, Suneel K.; Srivastava, Sanjeev K.

    2015-01-01

    The Pd1 -xNix alloy system is an established ideal transition-metal system possessing a composition-induced paramagnetic-to-ferromagnetic quantum phase transition (QPT) at the critical concentration xc˜0.026 in bulk. A low-temperature non-Fermi liquid (NFL) behavior around xc usually indicates the presence of quantum criticality (QC) in this system. In this work, we explore the existence of such a QPT in nanoparticles of this alloy system. We synthesized single-phase, polydispersed and 40-50 nm mean diameter crystalline nanoparticles of Pd1 -xNix alloys, with x near xc and beyond, by a chemical reflux method. In addition to the determination of the size, composition, phase, and crystallinity of the alloys by microscopic and spectroscopic techniques, the existence of a possible QPT was explored by resistivity and dc magnetization measurements. A dip in the value of the exponent n near xc, and a concomitant peak in the constant A of the A Tn dependence of the low-temperature (T ) resistivity indicate the presence of a quantum-like phase transition in the system. The minimum value of n , however, remains within the Fermi liquid regime (n >2 ). The dc magnetization results suggest an anticipatory presence of a superparamagnetic-to-ferromagnetic QPT in the mean-sized nanoparticles. The observation of a possible quantum critical NFL behavior (n <2 ) through resistivity is argued to be inhibited by the electron-magnon scatterings present in the smaller nanoparticles.

  14. Magnetic ordering and non-Fermi-liquid behavior in the multichannel Kondo-lattice model

    NASA Astrophysics Data System (ADS)

    Irkhin, Valentin Yu.

    2016-05-01

    Scaling equations for the Kondo lattice in the paramagnetic and magnetically ordered phases are derived to next-leading order with account of spin dynamics. The results are applied to describe various mechanisms of the non-Fermi-liquid (NFL) behavior in the multichannel Kondo-lattice model where a fixed point occurs in the weak-coupling region. The corresponding temperature dependences of electronic and magnetic properties are discussed. The model describes naturally formation of a magnetic state with soft boson mode and small moment value. An important role of Van Hove singularities in the magnon spectral function is demonstrated. The results are rather sensitive to the type of magnetic ordering and space dimensionality, the conditions for NFL behavior being more favorable in the antiferromagnetic and 2D cases.

  15. Lectures of Fermi liquid theory

    SciTech Connect

    Bedell, K.S.

    1993-07-01

    The Fermi liquid theory was first introduced by Landau in 1956 to provide a theoretical basis for the properties of strongly correlated Fermi systems. This theory has proven to be crucial for our understanding of a broad range of materials. These include liquid {sup 3}He, {sup 3}He-{sup 4}He mixtures, simple metals, heavy-fermions, and nuclear matter to name a few. In the high temperature superconductors questions have been raised regarding the applicability of Fermi liquid theory to the normal state behavior of these materials. I will not address this issue in these lectures. My focus will be to summarize the foundations of this theory and to explore the consequences. These lectures are in part a summary of the excellent review article by Baym and Pethick and the books by Pines and Nozieres and Baym and Pethick. They include as well a summary of some articles that I have authored and co-authored. In the main body of the lectures I will not make any additional references to the books or articles. In the absence of reading the original materials, my lectures should provide the essentials of a mini-course in Fermi liquid theory.

  16. Lectures of Fermi liquid theory

    SciTech Connect

    Bedell, K.S.

    1993-01-01

    The Fermi liquid theory was first introduced by Landau in 1956 to provide a theoretical basis for the properties of strongly correlated Fermi systems. This theory has proven to be crucial for our understanding of a broad range of materials. These include liquid [sup 3]He, [sup 3]He-[sup 4]He mixtures, simple metals, heavy-fermions, and nuclear matter to name a few. In the high temperature superconductors questions have been raised regarding the applicability of Fermi liquid theory to the normal state behavior of these materials. I will not address this issue in these lectures. My focus will be to summarize the foundations of this theory and to explore the consequences. These lectures are in part a summary of the excellent review article by Baym and Pethick and the books by Pines and Nozieres and Baym and Pethick. They include as well a summary of some articles that I have authored and co-authored. In the main body of the lectures I will not make any additional references to the books or articles. In the absence of reading the original materials, my lectures should provide the essentials of a mini-course in Fermi liquid theory.

  17. Kondo effect and non-Fermi-liquid behavior in Dirac and Weyl semimetals

    NASA Astrophysics Data System (ADS)

    Principi, Alessandro; Vignale, Giovanni; Rossi, E.

    2015-07-01

    We study the Kondo effect in three-dimensional (3D) Dirac materials and Weyl semimetals. We find the scaling of the Kondo temperature with respect to the doping n and the coupling J between the moment of the magnetic impurity and the carriers of the semimetal. We consider the interplay of long-range scalar disorder and Kondo screening and find that it causes the Kondo effect to be characterized not by a Kondo temperature, but by a distribution of Kondo temperatures with features that cause the appearance of strong non-Fermi-liquid behavior. We then consider the effect of Kondo screening, and of the interplay of Kondo screening and long-range scalar disorder, on the transport properties of Weyl semimetals. Finally, we compare the properties of the Kondo effect in 3D and 2D Dirac materials such as graphene and topological insulators.

  18. Non Fermi liquid behavior in strongly correlated f-electron materials

    SciTech Connect

    Maple, M.B.; Seaman, C.L.; Gajewski, D.A.; Dalichaouch, Y.; Barbetta, V.B.; Andrade, M.C. de; Mook, H.A.; Lukefahr, H.G.; Bernal, O.O.; MacLaughlin, D.E.

    1994-04-01

    Evidence for non Fermi liquid (NFL) behavior in Y{sub 1{minus}x}U{sub x}Pd{sub 3} and related systems is reviewed and discussed within the context of possible microscopic mechanisms. Low temperature electrical resistivity, specific heat, and magnetic susceptibility measurements on the Th{sub 1{minus}x}U{sub x}Pd{sub 2}Al{sub 3} system reveal unconventional Kondo behavior with NFL low temperature characteristics. Magnetic susceptibility measurements on UCu{sub 3.5}Pd{sub 1.5}, which has previously been shown to exhibit NFL behavior, are presented. Some systematics of the NFL low temperature behavior observed in several f-electron materials include a linear temperature dependence of the electrical resistivity {rho} {approximately} 1 {minus} aT with either positive or negative coefficient a, a logarithmically diverging specific heat C/T {approximately} {minus}lnT, and T{sup 1/2} asymptotic behavior of the magnetic susceptibility {Chi} {approximately} 1 {minus} T{sup 1/2}.

  19. Observation of non-Fermi liquid behavior in hole-doped LiFe1 -xVxAs

    NASA Astrophysics Data System (ADS)

    Xing, L. Y.; Shi, X.; Richard, P.; Wang, X. C.; Liu, Q. Q.; Lv, B. Q.; Ma, J.-Z.; Fu, B. B.; Kong, L.-Y.; Miao, H.; Qian, T.; Kim, T. K.; Hoesch, M.; Ding, H.; Jin, C. Q.

    2016-09-01

    We synthesized a series of V-doped LiFe1 -xVxAs single crystals. The superconducting transition temperature Tc of LiFeAs decreases rapidly at a rate of 7 K per 1% V. The Hall coefficient of LiFeAs switches from negative to positive with 4.2% V doping, showing that V doping introduces hole carriers. This observation is further confirmed by the evaluation of the Fermi surface volume measured by angle-resolved photoemission spectroscopy (ARPES), from which a 0.3 hole doping per V atom introduced is deduced. Interestingly, the introduction of holes does not follow a rigid band shift. We also show that the temperature evolution of the electrical resistivity as a function of doping is consistent with a crossover from a Fermi liquid to a non-Fermi liquid. Our ARPES data indicate that the non-Fermi liquid behavior is mostly enhanced when one of the hole dx z/dy z Fermi surfaces is well nested by the antiferromagnetic wave vector to the inner electron Fermi surface pocket with the dx y orbital character. The magnetic susceptibility of LiFe1 -xVxAs suggests the presence of strong magnetic impurities following V doping, thus providing a natural explanation to the rapid suppression of superconductivity upon V doping.

  20. Non-Fermi-liquid behavior and spin fluctuations in doped UAl{sub 2}

    SciTech Connect

    Mayr, F.; Blanckenhagen, G.v.; Stewart, G.R.

    1997-01-01

    Using the canonical spin-fluctuation system UAl{sub 2} as a starting point, via negative chemical pressure (doping with Y) we have expanded d{sub U-U} in a system known to be near the Hill limit of f-electron localization, and characterized the samples via resistivity, magnetic susceptibility, and specific-heat measurements. All system parameters, including magnetic susceptibility, specific heat {gamma} ({equivalent_to}C/Tlim{sub T{r_arrow}0}), and spin-fluctuation temperature, behave monotonically. For U{sub 1{minus}x}Y{sub x}Al{sub 2}, 0.30{le}x{le}0.70, spin-glass behavior is found with T{sub f}{approx_equal};5.1{plus_minus}0.5 K. This spin-glass behavior weakens (T{sub f} sinks, smaller magnetic signature, no specific-heat anomaly) for x{ge}0.75 while, at the same time, the spin-fluctuation T{sup 3}lnT term also gradually disappears from the specific heat. For x{ge}0.875, a non-Fermi-liquid (nFl) lnT term is found in the low temperature C/T. This new, perhaps equilibrium, ground state persists upon further dilution of the U ions with Y. Thus, we report on the evolution of nFl behavior in the neighborhood of a spin-glass ground state but, indeed, directly out of a yet weaker form of magnetism than heretofore reported, that of spin fluctuations. {copyright} {ital 1997} {ital The American Physical Society}

  1. Non-Fermi liquid behavior and non-universal superconducting gap structure in Fe-pnictides

    NASA Astrophysics Data System (ADS)

    Matsuda, Yuji

    2010-03-01

    The discovery of Fe-pnictide superconductors with Tc exceeding 55 K raises fundamental questions about origin of high-Tc superconductivity. Here we report the systematic studies of the normal-state charge transport, Fermi surface structure and superconducting gap structure in high-quality single crystals of BaFe2(As1-xPx)2 (0 <=x <=0.71), ranging from the SDW state to overdoped Fermi liquid state. Near the SDW boundary, the transport coefficients, including resistivity, Hall coefficient and magnetoresistance, exhibit striking deviations from the Fermi liquid properties [1]. The Fermi surface structure determined by the dHvA effect shows that in the superconducting dome the volume of the electron and hole sheets shrink linearly and the effective masses become strongly enhanced with decreasing x [2]. It is likely that these trends originate from the many-body interaction which gives rise to superconductivity. The penetration depth, thermal conductivity and NMR data for BaFe2(As0.67P0.33)2 (Tc=30 K) provide unambiguous evidence for line nodes in the superconducting gap function [3], in sharp contrast to the other Fe-based compounds with fully gapped structure. This indicates that the gap structure of Fe-based high-Tc superconductors is not universal.[1] S. Kasahara et al., arXiv:0905.4427 [2] H. Shishido et al., arXiv:0910.3634 [3] K. Hashimoto et al., arXiv:0907.4399 [4] K. Hashimoto et al., Phys. Rev. Lett. 102, 017002 (2009), ibid 102, 207001 (2009).

  2. Spin-Fluctuation-Induced Non-Fermi-Liquid Behavior with Suppressed Superconductivity in LiFe1 -xCoxAs

    NASA Astrophysics Data System (ADS)

    Dai, Y. M.; Miao, H.; Xing, L. Y.; Wang, X. C.; Wang, P. S.; Xiao, H.; Qian, T.; Richard, P.; Qiu, X. G.; Yu, W.; Jin, C. Q.; Wang, Z.; Johnson, P. D.; Homes, C. C.; Ding, H.

    2015-07-01

    We study a series of LiFe1 -xCox As compounds with different Co concentrations by transport, optical spectroscopy, angle-resolved photoemission spectroscopy, and nuclear magnetic resonance. We observe a Fermi-liquid to non-Fermi-liquid to Fermi-liquid (FL-NFL-FL) crossover alongside a monotonic suppression of the superconductivity with increasing Co content. In parallel to the FL-NFL-FL crossover, we find that both the low-energy spin fluctuations and Fermi surface nesting are enhanced and then diminished, strongly suggesting that the NFL behavior in LiFe1 -xCox As is induced by low-energy spin fluctuations that are very likely tuned by Fermi surface nesting. Our study reveals a unique phase diagram of LiFe1 -xCox As where the region of NFL is moved to the boundary of the superconducting phase, implying that they are probably governed by different mechanisms.

  3. Anisotropic Non-Fermi Liquids

    NASA Astrophysics Data System (ADS)

    Sur, Shouvik; Lee, Sung-Sik

    We study non-Fermi liquids that arise at quantum critical points associated with spin (SDW) and charge density wave (CDW) transitions in metals with twofold rotational symmetry. We use the `codimensional' regularization scheme, where a one-dimensional Fermi surface is embedded in 3 - ɛ dimensional momentum space. In three dimensions, quasilocal marginal Fermi liquids arise at the SDW and CDW critical points. Below three dimensions, a perturbative anisotropic non-Fermi liquid state is realized at the SDW critical point, where not only time but also different spatial coordinates develop distinct anomalous dimensions. The stable non-Fermi liquid exhibits an emergent algebraic nesting as the patches of the Fermi surface are deformed into a universal power-law shape near the hot spots. Due to the anisotropic scaling, the energy of spin fluctuations disperse with different power laws in different momentum directions. In contrast, at the CDW critical point, the perturbative expansion breaks down immediately below three dimensions as the interaction renormalizes the speed of charge fluctuations to zero within a finite renormalization group scale.

  4. Non-Fermi-Liquid Behavior on an Iron-Based Itinerant Electron Magnet Fe3Mo3N

    NASA Astrophysics Data System (ADS)

    Waki, Takeshi; Terazawa, Shinsuke; Tabata, Yoshikazu; Oba, Fumiyasu; Michioka, Chishiro; Yoshimura, Kazuyoshi; Ikeda, Shugo; Kobayashi, Hisao; Ohoyama, Kenji; Nakamura, Hiroyuki

    2010-04-01

    We report magnetic, calorimetric, and transport properties of an iron-based itinerant electron magnet Fe3Mo3N. Magnetic susceptibility shows a Curie-Weiss behavior at high temperatures and takes a broad maximum at around 75 K. The absence of magnetic long range order was confirmed by 57Fe-Mössbauer and neutron diffraction measurements. C/T shows a divergent behavior following -log T at low temperatures and reaches 128 mJ/(f.u.mol K2) at 0.5 K. The deviation from the T2 power law of resistivity also suggests a non-Fermi-liquid (NFL) behavior. The observed C/T and χ are enhanced compared with the values estimated from the theoretical density of states, suggesting a strong magnetic enhancement. The NFL behaviors indicate that Fe3Mo3N is one of the ideal systems located in the vicinity of the ferromagnetic quantum critical point.

  5. Nested-Fermi-liquid theory

    SciTech Connect

    Virosztek, A.; Ruvalds, J. )

    1990-09-01

    The susceptibility and quasiparticle self-energy are found to exhibit anomalous behavior in nested-Fermi-liquid (NFL) systems that have nearly parallel sections of the Fermi surface. Electron-electron scattering yields damping much stronger than the conventional electron-gas result and predicts a linear temperature variation of the resistivity. The susceptibility {chi}{sub NFL}{sup {prime}{prime}}({bold q},{omega}) for nested fermions is calculated at {bold q}{approx equal}{bold Q}, where {bold Q} is a typical nesting wave vector. The NFL susceptibility is linear in frequency up to a crossover region near {omega}{approx equal}4{ital T} where a saturation to a constant value occurs. The above features, as well as various theoretical constraints, are highly sensitive to the strength of the electron-electron coupling and to the degree of nesting. The relevance of the NFL results to superconducting oxides is briefly examined, with emphasis on the resistivity and the photoemission data, which supports the calculated damping {Gamma}({omega}{gt}{ital T}){approx equal}{alpha}{omega} with an intermediate on-site Coulomb coupling.

  6. Non-fermi liquid behavior of the organic superconductor κ-(BEDT-TTF)4Hg2.89Br8 probed by 13C-NMR

    NASA Astrophysics Data System (ADS)

    Eto, Yoshihiro; Itaya, Megumi; Kawamoto, Atsushi

    2010-06-01

    We assessed 13C-NMR measurements in an organic salt, κ-(BEDT-TTF)4Hg2.89Br8, which exhibits superconductivity at 4.3 K under ambient pressure. We observed that (T1T)-1 of H // and ⊥ layer at ambient pressure increased as the temperature was decreased to 7 K, but decreased further at lower temperatures, suggesting that the decrease of (T1T)-1 was not due to the superconductive fluctuations, but due to the magnetism of the conduction electrons. Application of pressure suppresses (T1T)-1, with (T1T)-1 becoming constant above 2 GPa. These results suggest that applying pressure alters the electron system from a non-Fermi liquid (NFL) to a Fermi liquid (FL) state and that antiferromagnetic fluctuations contribute to the origin of NFL behavior. Whereas most organic conductors show Fermi liquid behavior, this salt is an organic superconductor that shows NFL behavior due to the antiferromagnetic fluctuations.

  7. Non-Fermi-liquid behavior in the specific heat over two decades of temperature in doped UPt{sub 3}

    SciTech Connect

    Trinkl, W.; Weilnhammer, U.; Corsepius, S.; Schreiner, T.; Scheidt, E.; Stewart, G.R.

    1996-07-01

    We have discovered, in contrast with most dopants {ital M}, that Hf (Zr) can be doped to quite high levels in U{sub 1{minus}{ital x}}M{sub {ital x}}Pt{sub 3}, up to {ital x}=0.15 (0.30). Above 5{percent} doping, the temperature dependence of the low-temperature upturn in {ital C}/{ital T} (specific heat divided by temperature) changes from {ital T}{sup 3}ln{ital T} (indicative of spin fluctuations) to {ital T}ln{ital T} [indicative of non-Fermi-liquid (NFL) behavior]. The specific heat NFL temperature dependence has been measured down to 0.1 K and is seen over more than two decades in temperature. The field dependence of the NFL specific heat is small, consistent with a quadrupolar moment model interpretation. A possible reason for the NFL behavior is discussed. {copyright} {ital 1996 The American Physical Society.}

  8. Non-Fermi liquid behavior and the undersceened Kondo effect in Fe1-yCoySi

    NASA Astrophysics Data System (ADS)

    Wu, Yan; Fulfer, Brad; Chan, Julia; Young, David; Ditusa, John

    2015-03-01

    Mn or Co substitutions into the narrow band-gap insulator FeSi introduce charge carriers, either holes or electrons, accompanied by an equal density of more localized magnetic moments resulting in an interesting insulator-to-metal transition (IMT). Mn doping of FeSi exhibits an IMT where the nascent metal displays intriguing field sensitive non-Fermi-Liquid (NFL) behavior due to the undercompensation of S = 1 impurity moments by the spin-1/2 hole carriers. Here, we present the results of an investigation of Fe1-yCoySi (0 <= y <= 0.1). Our magnetization and susceptibility measurements indicate that for y<0.03 Co-impurities alsointroduce a S = 1 magnetic moment that have a tendency to form singlets whereas for larger ya ferromagnetic interaction that grows with y. We have discovered a NFLbehavior for y<0.03 that evolves into the standard disordered Fermi-liquid form either by applying a magnetic field or by increasing y. The results of specific heat measurements on Fe1-yCoySi,performed to explore the underlying underscreened Kondo mechanism, to investigate its variation with field and composition,and to compare with our Fe1-xMnxSi data will be presented.

  9. Beyond the Fermi liquid paradigm: hidden Fermi liquids.

    PubMed

    Jain, J K; Anderson, P W

    2009-06-01

    An intense investigation of possible non-Fermi liquid states of matter has been inspired by two of the most intriguing phenomena discovered in the past quarter century, namely, high-temperature superconductivity and the fractional quantum Hall effect. Despite enormous conceptual strides, these two fields have developed largely along separate paths. Two widely employed theories are the resonating valence bond theory for high-temperature superconductivity and the composite fermion theory for the fractional quantum Hall effect. The goal of this perspective article is to note that they subscribe to a common underlying paradigm: They both connect these exotic quantum liquids to certain ordinary Fermi liquids residing in unphysical Hilbert spaces. Such a relation yields numerous nontrivial experimental consequences, exposing these theories to rigorous and definitive tests.

  10. New physics of metals: fermi surfaces without Fermi liquids.

    PubMed Central

    Anderson, P W

    1995-01-01

    I relate the historic successes, and present difficulties, of the renormalized quasiparticle theory of metals ("AGD" or Fermi liquid theory). I then describe the best-understood example of a non-Fermi liquid, the normal metallic state of the cuprate superconductors. PMID:11607559

  11. Non-Fermi liquid behavior with and without quantum criticality in Ce1-xYbxCoIn5

    NASA Astrophysics Data System (ADS)

    Singh, Y. P.; Hu, T.; Shu, L.; Janoschek, M.; Dzero, M.; Maple, M. B.; Almasan, C. C.

    2013-03-01

    In a growing number of f-electron systems the non-Fermi liquid (NFL) behavior occurs in the absence of an obvious quantum phase transition (QPT), which takes place at a quantum critical point (QCP). An intriguing candidate is Ce1-xYbxCoIn5 that exhibits an unconventional T - x phase diagram without an apparent QCP. Therefore, it is important to elucidate the nature of the NFL behavior and to search for possible QCPs in this system Here we reveal a field induced QCP (HQCP) through normal state magneto-resistivity measurements and find its evolution with x. The full suppression of HQCP for x > 0.2 has surprisingly little effect on the Kondo lattice coherence. At low Yb concentrations, resistivity consists of two contributions with linear and sub-linear temperature dependences, while at higher concentrations only the sub-linear term is present. These results imply that the NFL behavior could be a new state of matter in its own right rather than a consequence of the underlying QPT. This work was supported by NSF (DMR-1006606 and DMR- 0844115), ICAM Branches Cost Sharing Fund from Institute for Complex Adaptive Matter, and Ohio Board of Regents (Grant OBR-RIP-220573) at KSU, and DOE (DE-FG02-04ER46105) at UCSD.

  12. Magnetism, spin fluctuations, and non-Fermi-liquid behavior in (U{sub x}La{sub 1-x}){sub 2}Zn{sub 17}

    SciTech Connect

    von Blanckenhagen, G.-F.; Scheidt, E.-W.; Schreiner, T.; Stewart, G. R.

    2001-08-01

    We present results of the low-temperature specific heat C of samples of the series (U{sub x}La{sub 1-x}){sub 2}Zn{sub 17}, combined with measurements of the low-temperature magnetic susceptibility ({chi}) and resistivity ({rho}). For x>0.8 we find antiferromagnetic order in coexistence with heavy-fermion behavior. An extrapolation of T{sub N} as a function of the uranium concentration implies that T{sub N} vanishes for x=0.8; at x=0.8, no magnetic order is detected experimentally at temperatures above 0.06 K. The non-Fermi-liquid (NFL) behavior predicted at such a point in the magnetic phase diagram may be observed, but not as clearly as in other systems; some of the behavior is more consistent with spin fluctuations. As the uranium concentration is lowered below x=0.8, C continues to rise in the low-temperature limit, while {chi}{proportional_to}{chi}{sub 0}-aT{sup 0.5}, but C seems to tend towards the behavior of a Fermi liquid with spin fluctuations at the lowest temperatures (T<0.25 K). First at x=0.3 the temperature dependence of C/T is found to be contrary to Fermi-liquid behavior, while {chi}{proportional_to}{chi}{sub 0}-a log T. Thus non-Fermi-liquid behavior is not found so unambiguously at the concentration where T{sub N} vanishes as expected by a quantum critical point theory, but rather at lower uranium concentrations. This presents the possibility that NFL behavior in (U{sub x}La{sub 1-x}){sub 2}Zn{sub 17} is not due to nearness to a quantum critical point, but rather to disorder or the presence of spin fluctuations.

  13. Non-Fermi-liquid behavior from partial nesting in multiorbital superconductors

    NASA Astrophysics Data System (ADS)

    Setty, Chandan; Phillips, Philip W.

    2016-03-01

    Partial nesting between two connected or disconnected regions of the Fermi surface leads to fractional powers of the Coulomb scattering lifetime as a function of temperature. This result is first demonstrated for a toy band structure where partial nesting occurs within a single band and between different regions of the Brillouin zone. A comparison is then made to a multiband scenario by studying the scattering rate of an effective two-orbital model that was proposed in the context of multiorbital superconductors. In the process, various model independent features affecting the temperature exponent n are identified. The logarithmically divergent contributions of the lowest order vertex correction to the multiorbital susceptibility, and the role played by nesting in suppressing these divergences, is analyzed. The relevance of these results is discussed keeping the recently observed anomalous resistivity in the Co doped iron superconductor LiFeAs as a backdrop.

  14. Study of non-Fermi Liquid behavior from partial nesting in multi-orbital superconductors

    NASA Astrophysics Data System (ADS)

    Setty, Chandan; Phillips, Philip

    Partial nesting between two connected or disconnected regions of the Fermi surface leads to fractional powers of the Coulomb scattering lifetime as a function of temperature and frequency. This result is first demonstrated for a toy band structure where partial nesting occurs within a single band and between different regions of the Brillouin zone. A comparison is then made to a multiband scenario by studying the scattering rate of an effective two orbital model that was proposed in the context of multi-orbital superconductors. In the process, various model independent factors affecting the temperature exponent, n, are identified. The logarithmically divergent contributions of the lowest order vertex correction to the multi-orbital susceptibility, and the role played by nesting in suppressing these divergences is analyzed. The relevance of these results is discussed keeping the recently observed anomalous resistivity in the Co doped Iron superconductor LiFeAs as a backdrop.

  15. Deviations from Fermi-Liquid Behavior above Tc in 2D Short Coherence Length Superconductors

    NASA Astrophysics Data System (ADS)

    Trivedi, Nandini; Randeria, Mohit

    1995-07-01

    We show that there are qualitative differences between the temperature dependence of the spin and charge correlations in the normal state of the 2D attractive Hubbard model using quantum Monte Carlo simulations. The one-particle density of states shows a pseudogap above Tc with a depleted N0 with decreasing T. The susceptibility χs and the low frequency spin spectral weight track N0, which explains the spin-gap scaling: 1/T1T~χsT. However, collective excitations contribute to the charge channel, and the compressibility dn/dμ is T independent. This anomalous ``spin-charge separation'' is shown to exist even at intermediate \\|U\\| where the momentum distribution nk gives evidence for a degenerate Fermi system.

  16. Evidence for a Common Physical Description of Non-Fermi-Liquid Behavior in Chemically Substituted f -Electron Systems

    SciTech Connect

    de Andrade, M.C.; Chau, R.; Dickey, R.P.; Dilley, N.R.; Freeman, E.J.; Gajewski, D.A.; Maple, M.B.; Movshovich, R.; Castro Neto, A.H.; Castilla, G.; Jones, B.A.

    1998-12-01

    The non-Fermi-liquid (NFL) behavior observed in the low temperature specific heat C(T) and magnetic susceptibility {chi}(T) of many chemically substituted f -electron systems is analyzed within the context of a recently developed theory based on Griffiths{close_quote} singularities. Measurements of C(T) and {chi}(T) in the systems Th{sub 1{minus}x}U {sub x}Pd{sub 2}Al{sub 3} , Y{sub 1{minus}x}U {sub x}Pd{sub 3} , and UCu{sub 5{minus}x }M{sub x} (M=Pd,thinspPt ) are found to be consistent with C(T)/T{proportional_to}{chi}(T){proportional_to}T{sup {minus}1+{lambda}} predicted by this model with {lambda}{lt}1 in the NFL regime. These results suggest that the NFL properties observed in a wide variety of disordered f -electron systems can be described within the context of a common physical picture. {copyright} {ital 1998} {ital The American Physical Society}

  17. Hidden non-Fermi liquid behavior caused by magnetic phase transition in Ni-doped Ba-122 pnictides

    PubMed Central

    Lee, Seokbae; Choi, Ki-Young; Jung, Eilho; Rho, Seulki; Shin, Soohyeon; Park, Tuson; Hwang, Jungseek

    2015-01-01

    We studied two BaFe2−xNixAs2 (Ni-doped Ba-122) single crystals at two different doping levels (underdoped and optimally doped) using an optical spectroscopic technique. The underdoped sample shows a magnetic phase transition around 80 K. We analyze the data with a Drude-Lorentz model with two Drude components (D1 and D2). It is known that the narrow D1 component originates from electron carriers in the electron-pockets and the broad D2 mode is from hole carriers in the hole-pockets. While the plasma frequencies of both Drude components and the static scattering rate of the broad D2 component show negligible temperature dependencies, the static scattering rate of the D1 mode shows strong temperature dependence for the both samples. We observed a hidden quasi-linear temperature dependence in the scattering rate of the D1 mode above and below the magnetic transition temperature while in the optimally doped sample the scattering rate shows a more quadratic temperature dependence. The hidden non-Fermi liquid behavior in the underdoped sample seems to be related to the magnetic phase of the material. PMID:26184412

  18. Magnetic Field Effect on Crossover Temperature from Non-Fermi Liquid to Fermi Liquid Behavior in f2-Impurity Systems with Crystalline-Electric-Field Singlet State Competing with Kondo--Yosida Singlet State

    NASA Astrophysics Data System (ADS)

    Nishiyama, Shinya; Miyake, Kazumasa

    2011-12-01

    We investigate the magnetic field dependence of the physical properties of f2-configuration systems with a crystalline-electric field (CEF) singlet ground state, which gives rise to a non-Fermi liquid (NFL) fixed point due to the competition between the Kondo--Yosida singlet and CEF singlet states. On the basis of the numerical renormalization group method, we find that the magnetic field breaks this NFL fixed point via two mechanisms: one causing the polarization of f-electrons and the other giving the ``channel'' anisotropy. These two mechanisms induce a difference in the magnetic field dependence of the characteristic temperature TF*(H), the crossover temperature from NFL to Fermi-liquid behavior. While the polarization of f-electrons gives TF*(H) \\propto Hx (x ≃ 2.0), the ``channel'' anisotropy gives the H-independent TF*(H). These two mechanisms cross over continuously at approximately the crossover magnetic field Hc, where an anomalous H-dependence of TF*(H) appears. Such TF*(H) well reproduces the NFL behaviors observed in Th1-xUxRu2Si2. We also find that the H-dependence of the resistivity and the magnetic susceptibility are in good agreement with the experimental results of this material. These results suggest that the NFL behaviors observed in Th1-xUxRu2Si2 can be understood if this material is located in the CEF singlet side near the critical phase boundary between the two singlet states.

  19. Neutron scattering studies of non-Fermi liquid behavior in Ce compounds

    NASA Astrophysics Data System (ADS)

    Park, J.-G.; Adroja, D. T.; McEwen, K. A.; Murani, A. P.; So, J.-Y.; Beirne, E.; Echizen, Y.; Takabatake, T.

    2002-03-01

    We have studied the inelastic neutron scattering from two Ce heavy fermion compounds, Ce(Ni0.935Cu0.065)Sn and Ce(Rh0.8Pd0.2)Sb, that are located at the magnetic-non-magnetic boundary. We find that the magnetic scattering follows a power law scaling behavior, and that the dynamical susceptibility, as deduced from the magnetic scattering, shows E/T scaling behavior with significantly different exponents for the two systems.

  20. Deviations from Fermi-liquid behavior in (2+1)-dimensional quantum electrodynamics and the normal phase of high-Tc superconductors

    NASA Astrophysics Data System (ADS)

    Aitchison, I. J. R.; Mavromatos, N. E.

    1996-04-01

    We argue that the gauge-fermion interaction in multiflavor quantum electrodynamics in (2+1) dimensions is responsible for non-Fermi-liquid behavior in the infrared, in the sense of leading to the existence of a nontrivial (quasi)fixed point that lies between the trivial fixed point (at infinite momenta) and the region where dynamical symmetry breaking and mass generation occurs. This quasifixed-point structure implies slowly varying, rather than fixed, couplings in the intermediate regime of momenta, a situation which resembles that of (four-dimensional) ``walking technicolor'' models of particle physics. The inclusion of wave-function renormalization yields marginal O(1/N) corrections to the ``bulk'' non-Fermi-liquid behavior caused by the gauge interaction in the limit of infinite flavor number. Such corrections lead to the appearance of modified critical exponents. In particular, at low temperatures there appear to be logarithmic scaling violations of the linear resistivity of the system of order O(1/N). The connection with the anomalous normal-state properties of certain condensed-matter systems relevant for high-temperature superconductivity is briefly discussed. The relevance of the large (flavor) N expansion to the Fermi-liquid problem is emphasized. As a partial result of our analysis, we point out the absence of charge-density-wave instabilities from the effective low-energy theory, as a consequence of gauge invariance.

  1. Local Moment, Itinerancy, and Deviation from Fermi-Liquid Behavior in NaxCoO2 for 0.71≤x≤0.84

    NASA Astrophysics Data System (ADS)

    Balicas, L.; Jo, Y. J.; Shu, G. J.; Chou, F. C.; Lee, P. A.

    2008-03-01

    Here we report the observation of Fermi surface (FS) pockets via the Shubnikov de Haas effect in NaxCoO2 for x=0.71 and 0.84, respectively. Our observations indicate that the FS expected for each compound intersects their corresponding Brillouin zones, as defined by the previously reported superlattice structures, leading to small reconstructed FS pockets, but only if a precise number of holes per unit cell is localized. For 0.71≤x<0.75 the coexistence of itinerant carriers and localized S=1/2 spins on a paramagnetic triangular superlattice leads at low temperatures to the observation of a deviation from standard Fermi-liquid behavior in the electrical transport and heat capacity properties, suggesting the formation of some kind of quantum spin-liquid ground state.

  2. Landau Theory of Helical Fermi Liquids.

    PubMed

    Lundgren, Rex; Maciejko, Joseph

    2015-08-01

    We construct a phenomenological Landau theory for the two-dimensional helical Fermi liquid found on the surface of a three-dimensional time-reversal invariant topological insulator. In the presence of rotation symmetry, interactions between quasiparticles are described by ten independent Landau parameters per angular momentum channel, by contrast with the two (symmetric and antisymmetric) Landau parameters for a conventional spin-degenerate Fermi liquid. We project quasiparticle states onto the Fermi surface and obtain an effectively spinless, projected Landau theory with a single projected Landau parameter per angular momentum channel that captures the spin-momentum locking or nontrivial Berry phase of the Fermi surface. As a result of this nontrivial Berry phase, projection to the Fermi surface can increase or lower the angular momentum of the quasiparticle interactions. We derive equilibrium properties, criteria for Fermi surface instabilities, and collective mode dispersions in terms of the projected Landau parameters. We briefly discuss experimental means of measuring projected Landau parameters.

  3. Correlation between non-Fermi-liquid behavior and antiferromagnetic fluctuations in (TMTSF)2PF6 observed using C13-NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Kimura, Yoshitaka; Misawa, Masaki; Kawamoto, Atsushi

    2011-07-01

    In the temperature-pressure phase diagram of the organic superconductor (TMTSF)2PF6 (TMTSF: tetramethyltetraselenafulvalene), the superconducting phase and the spin-density-wave (SDW) phase are adjacent to each other. This salt exhibits non-Fermi-liquid (NFL) behavior and superconductivity under pressure. Its superconductive property does not exist at higher pressures where Fermi-liquid (FL) behavior is exhibited. In order to investigate the origin of NFL behavior, systematic C13-NMR measurement of this salt has been assessed under pressure in a wide temperature range. At low temperatures, (T1T)-1 increases, and this increase is suppressed by the increasing pressure. These results suggest that applying pressure alters the electron system from the NFL to the FL state, and that antiferromagnetic fluctuations contribute to the origin of NFL behavior. The connection between the emergence of FL behavior and the disappearance of superconductivity suggests that the SDW fluctuation relates to the mechanism of the superconductivity in (TMTSF)2PF6.

  4. Non-fermi liquid and spin-glass behavior of the Sc{sub 1-x}U{sub x}Pd{sub 3} system

    SciTech Connect

    Gajewski, D.A.; Allenspach, P.; Seaman, C.L.; Maple, M.B. |

    1993-09-01

    Previous electrical resistivity {rho}T, magnetic susceptibility {chi}T, and specific heat C(T) measurements on the Y{sub 1-x}U{sub x}Pd{sub 3} system have revealed Kondo behavior for 0 < {times} < 0.2 and spin-glass-like behavior for 0.3 < {times} < 0.5. The Kondo behavior is unusual and characterized by non-Fermi liquid behavior at low temperatures T {much_lt} T{sub K}, where T{sub K} is the Kondo temperature: {rho}T/{rho}(0) {approximately} 1 {minus} T/(aT{sub K}), and C(T)/T {approximately} 1 {minus} (1/T{sub K})1nT with evidence for a finite T = 0 residual entropy S(0) = (R/2)1n(2). We report measurements of {rho}T, {chi}T, and C(T) on the Sc{sub 1-x}U{sub x}Pd{sub 3} system which reveal similar Kondo, non-Fermi liquid, and spin-glass behaviors.

  5. Renormalization group and the superconducting susceptibility of a Fermi liquid

    SciTech Connect

    Parameswaran, S. A.; Sondhi, S. L.; Shankar, R.

    2010-11-15

    A free Fermi gas has, famously, a superconducting susceptibility that diverges logarithmically at zero temperature. In this paper we ask whether this is still true for a Fermi liquid and find that the answer is that it does not. From the perspective of the renormalization group for interacting fermions, the question arises because a repulsive interaction in the Cooper channel is a marginally irrelevant operator at the Fermi liquid fixed point and thus is also expected to infect various physical quantities with logarithms. Somewhat surprisingly, at least from the renormalization group viewpoint, the result for the superconducting susceptibility is that two logarithms are not better than one. In the course of this investigation we derive a Callan-Symanzik equation for the repulsive Fermi liquid using the momentum-shell renormalization group, and use it to compute the long-wavelength behavior of the superconducting correlation function in the emergent low-energy theory. We expect this technique to be of broader interest.

  6. Disorder-driven non-Fermi liquid behavior in single-crystalline Ce2Co0.8Si3.2.

    PubMed

    Szlawska, M; Kaczorowski, D

    2014-01-01

    A single crystal of the Ce-based ternary silicide Ce2Co0.8Si3.2, which crystallizes with a hexagonal AlB2-type related structure, was studied by means of magnetization, resistivity and heat capacity measurements. The compound was characterized as a Kondo paramagnet down to 0.4 K. Its low-temperature behavior is dominated by distinct non-Fermi liquid features, most likely arising due to structural disorder in the nonmagnetic-atom sublattice. PMID:24292411

  7. Quantum Melting of Charge Ice and Non-Fermi-Liquid Behavior: An Exact Solution for the Extended Falicov-Kimball Model in the Ice-Rule Limit

    NASA Astrophysics Data System (ADS)

    Udagawa, Masafumi; Ishizuka, Hiroaki; Motome, Yukitoshi

    2010-06-01

    An exact solution is obtained for a model of itinerant electrons coupled to ice-rule variables on the tetrahedron Husimi cactus, an analogue of the Bethe lattice of corner-sharing tetrahedra. It reveals a quantum critical point with the emergence of non-Fermi-liquid behavior in melting of the “charge ice” insulator. The electronic structure is compared with the numerical results for the pyrochlore-lattice model to elucidate the physics of electron systems interacting with the tetrahedron ice rule.

  8. Non-Fermi Liquid Behavior in Quasi-One-Dimensional Li0.9Mo6O17

    SciTech Connect

    Hager, J.; Matzdorf, R.; He, Jian; Jin, Rongying; Mandrus, David; Cazalilla, M.; Plummer, E Ward

    2005-01-01

    We present temperature dependent scanning tunneling spectroscopy data of the quasi-one-dimensional conductor Li{sub 0.9}Mo{sub 6}O{sub 17}. The differential tunneling current in our low-temperature spectra shows a power-law behavior around the Fermi energy, which is expected for a clean Luttinger liquid. The power-law exponent is found to be 0.6. Spectra for a temperature range of 5 to 55 K can be fitted fairly well with a model for tunneling into a Luttinger liquid at the appropriate temperature. A fit with a model based on a zero bias anomaly is significantly worse compared to the Luttinger liquid model. No signature of a phase transition at T = 24 K is observed in our temperature dependent data.

  9. Holographic Metals and the Fractionalized Fermi Liquid

    SciTech Connect

    Sachdev, Subir

    2010-10-08

    We show that there is a close correspondence between the physical properties of holographic metals near charged black holes in anti-de Sitter (AdS) space, and the fractionalized Fermi liquid phase of the lattice Anderson model. The latter phase has a ''small'' Fermi surface of conduction electrons, along with a spin liquid of local moments. This correspondence implies that certain mean-field gapless spin liquids are states of matter at nonzero density realizing the near-horizon, AdS{sub 2}xR{sup 2} physics of Reissner-Nordstroem black holes.

  10. Holographic metals and the fractionalized fermi liquid.

    PubMed

    Sachdev, Subir

    2010-10-01

    We show that there is a close correspondence between the physical properties of holographic metals near charged black holes in anti-de Sitter (AdS) space, and the fractionalized Fermi liquid phase of the lattice Anderson model. The latter phase has a "small" Fermi surface of conduction electrons, along with a spin liquid of local moments. This correspondence implies that certain mean-field gapless spin liquids are states of matter at nonzero density realizing the near-horizon, AdS₂ × R² physics of Reissner-Nordström black holes. PMID:21230891

  11. Fermi Liquid in a Torsional Oscillator

    NASA Astrophysics Data System (ADS)

    Virtanen, T. H.; Thuneberg, E. V.

    2012-12-01

    We study the transverse acoustic impedance of normal Fermi liquid inside a torsionally oscillating cylindrical container. We use Landau's Fermi liquid theory, and our approach is applicable to both normal 3He and mixtures of 3He in superfluid 4He. The fluid causes dissipation and a change of the resonant frequency of the oscillator. Usually, a liquid medium increases the moment of inertia of the oscillator, but we show that for a suitable choice of container radius and driving frequency, the Fermi liquid can actually decrease the inertia and increase the resonant frequency. Results of numerical calculations for all values of mean free path l are shown and comparison is made to both hydrodynamic theory and simple kinetic theory in the ballistic limit.

  12. Strongly correlated electron behavior: Superconductivity and non-Fermi liquid behavior in cerium-R-cobalt-indium

    NASA Astrophysics Data System (ADS)

    Gonzales, Eileen

    CeCoIn5 has received a great deal of attention in recent years due to its exotic normal state behavior and possibly magnetically mediated superconductivity. In this work, we performed a two-part doping study of CeCoIn5. First we investigated single crystals with dilute concentrations of several rare earths in the lanthanide series for Ce0:95R 0:05CoIn5. Second, in a more extensive substitution study, ytterbium was doped into the cerium sites for a full range of concentrations. For both cases, the synthesized compounds exhibited normal state NFL behavior, Kondo coherence, and magnetic anisotropy. In the rare earth study we found that the suppression of the superconducting transition Tc does not follow the conventional rate of suppression when a paramagnetic impurity is introduced into the system. In the ytterbium study a possible valence transition occurs for the Yb ion with increasing concentrations into the Ce sites. Single crystals of Ce0:95R0:05CoIn5 and Ce 1-xRxCoIn 5 are investigated by means of x-ray powder diffraction, resistivity as function of temperature, and magnetic susceptibility.

  13. Berry curvature on the fermi surface: anomalous Hall effect as a topological fermi-liquid property.

    PubMed

    Haldane, F D M

    2004-11-12

    The intrinsic anomalous Hall effect in metallic ferromagnets is shown to be controlled by Berry phases accumulated by adiabatic motion of quasiparticles on the Fermi surface, and is purely a Fermi-liquid property, not a bulk Fermi sea property like Landau diamagnetism, as has been previously supposed. Berry phases are a new topological ingredient that must be added to Landau Fermi-liquid theory in the presence of broken inversion or time-reversal symmetry.

  14. Strongly-disordered hybridization and non-Fermi liquid behavior in CePt4Ge12-xSbx studied with thermoelectric power

    NASA Astrophysics Data System (ADS)

    White, Benjamin; Huang, Kevin; Maple, M. Brian

    2014-03-01

    Non-Fermi liquid (NFL) behavior is commonly associated with the presence of a nearby quantum critical point, but can also be observed in other scenarios. In a clean system, hybridization between localized and itinerant electron states can be characterized by a single Kondo temperature TK, but introducing chemical disorder can lead to a wide distribution of TK values. Given sufficient disorder, the resulting distribution will tend to include an appreciable number of localized electron states which are characterized by TK ~ 0 K, and NFL behavior emerges. A Kondo-disorder type of NFL behavior was recently reported in the filled skutterudite system CePt4Ge12-xSbx in the vicinity of x = 1 . We performed a study of the thermoelectric power S(T) for this system and observed an evolution of S(T) with x that is dramatic and broadly consistent with the boundaries of the proposed phase diagram. The effect of disordered hybridization is clearly observed in a low-temperature feature in S(T) in the range 0 . 5 <= x <= 1 . 5 and NFL behavior is also observed at x = 1. These results clearly demonstrate how sensitively S(T) is able to probe a Kondo disorder system. Research was performed with support from the US DOE grant DE-FG02-04-ER46105.

  15. Remarks on Fermi liquid from holography

    SciTech Connect

    Kulaxizi, Manuela; Parnachev, Andrei

    2008-10-15

    We investigate the signatures of Fermi liquid formation in the N=4 super Yang-Mills theory coupled to fundamental hypermultiplet at nonvanishing chemical potential for the global U(1) vector symmetry. At strong 't Hooft coupling the system can be analyzed in terms of the D7-brane dynamics in the AdS{sub 5}xS{sup 5} background. The phases with vanishing and finite charge density are separated at zero temperature by a quantum phase transition. In the case of vanishing hypermultiplet mass, Karch, Son, and Starinets discovered a gapless excitation whose speed equals the speed of sound. We find that this zero sound mode persists to all values of the hypermultiplet mass, and its speed vanishes at the point of phase transition. The value of critical exponent and the ratio of the velocities of zero and first sounds are consistent with the predictions of Landau Fermi liquid theory at strong coupling.

  16. ``Hidden order,'' heavy electron ferromagnetism, and non-Fermi liquid behavior in the pseudoternary system URu2-x Re x Si 2

    NASA Astrophysics Data System (ADS)

    Maple, M. Brian

    2011-03-01

    The identity of the ordered phase that occurs at temperatures below To = 17 K in the heavy fermion compound URu 2 Si 2 has eluded researchers for two and a half decades. Features in various physical properties associated with this so-called ``hidden order'' (HO) phase are reminiscent of a charge or spin density wave that forms a gap over about 40% of the Fermi surface below To , while the remainder of the Fermi surface is gapped by the superconductivity below Tc = 1.5 K. In order to attain a better understanding of these phenomena, the physical properties of URu 2 Si 2 have been studied as a function of applied pressure, chemical substitution, and magnetic field. Whereas the application of pressure suppresses the superconductivity and induces a phase transition from the HO phase to an antiferromagnetic phase, the substitution of Re for Ru results in the suppression of the superconductivity and the HO transition, the nearby emergence of ferromagnetic (FM) order, and unique critical behavior associated with the FM phase. Magnetization measurements on the URu 2-x Re x Si 2 pseudoternary system as a function of x reveal the onset of ferromagnetism at a concentration xcr ~ 0.15 , which apparently represents a FM quantum critical point. Non-Fermi liquid (NFL) behavior in the physical properties such as the electrical resistivity and specific heat at low temperatures is found to extend deep into the FM region of the T - x phase diagram. Experiments conducted on URu 2-x Re x Si 2 single crystals to investigate the superconducting, HO, and FM phases, characterize the NFL behavior, and establish the T - x phase diagram are described. The experimental results are compared to theoretical models for ferromagnetism in a Kondo lattice. Research performed in collaboration with N. P. Butch, J. R. Jeffries, B. T. Yukich, and D. A. Zocco Research supported by the U.S. Department of Energy under Grant Nos. DE-FG02-04ER46105 (crystal growth) and DE-FG52-06NA26205 (high pressure

  17. Non-Fermi-liquid behavior of the organic superconductor κ-(BEDT-TTF)4Hg2.89Br8 probed by C13 NMR

    NASA Astrophysics Data System (ADS)

    Eto, Yoshihiro; Itaya, Megumi; Kawamoto, Atsushi

    2010-06-01

    An organic salt, κ-(BEDT-TTF)4Hg2.89Br8 exhibits superconductivity at 4.3 K under ambient pressure suggesting non-Fermi-liquid (NFL) behavior just above Tc . Whereas most organic superconductors are controlled by the bandwidth in the half-filled electron system, this salt realizes a carrier doping away from the half-filled electron system as well as high- Tc cuprates. In order to investigate the origin of NFL behavior, we assessed C13 -NMR measurements in this salt and observed the antiferromagnetic fluctuation as same as in an organic antiferromagnet κ-(BEDT-TTF)2Cu[N(CN)2]Cl with the gap structure. Application of pressure suppresses (T1T)-1 and shifts its maximum to lower temperatures with (T1T)-1 becoming constant above 2 GPa. These results suggest that applying pressure alters the electron system from NFL to FL state and that antiferromagnetic fluctuations contribute to the origin of NFL behavior.

  18. Magnetically Robust Non-Fermi Liquid Behavior in Heavy Fermion Systems with f2-Configuration: Competition between Crystalline-Electric-Field and Kondo-Yosida Singlets

    NASA Astrophysics Data System (ADS)

    Nishiyama, Shinya; Matsuura, Hiroyasu; Miyake, Kazumasa

    2010-10-01

    In f2-based heavy fermion systems with a crystalline-electric-field (CEF) singlet ground state, the non-Fermi liquid (NFL) arises around the quantum critical point (QCP) due to the competition between the CEF singlet and the Kondo-Yosida singlet states. In such a case, the characteristic temperature TF* at which the entropy starts to decrease toward zero is suppressed by the effect of the competition, compared to both energy scales characterizing each singlet state, the lower Kondo temperature (TK2) and the CEF splitting (Δ). We show that in the case of tetragonal symmetry TF* is not affected by the magnetic field up to Hz* which is determined by the distance from the QCP or characteristic energy scales of each singlet states, not by TF* itself. As a result, in the vicinity of QCP, there are parameter regions where the NFL is robust against the magnetic field, at an observable temperature range T > TF*, up to Hz* which is far larger than TF* and less than \\min(TK2,Δ). Our result suggests that such an anomalous NFL behavior can arise also in systems with other CEF symmetry, which might provide us with the basis to understand the anomalous behaviors of UBe13.

  19. Non-Fermi liquid behavior, the Becchi-Rouet-Stora-Tyutin identity in the dense quark-gluon plasma, and color superconductivity

    SciTech Connect

    Brown, William E.; Liu, James T.; Ren, Hai-cang

    2000-09-01

    At sufficiently high baryon densities, the physics of a dense quark-gluon plasma may be investigated through the tools of perturbative QCD. This approach has recently been successfully applied to the study of color superconductivity, where the dominant di-quark pairing interaction arises from one gluon exchange. Screening in the plasma leads to novel behavior, including a remarkable non-BCS scaling of T{sub C}, the transition temperature to the color superconducting phase. Radiative corrections to one gluon exchange were previously considered and found to affect T{sub C}. In particular, the quark self-energy in a plasma leads to non-Fermi liquid behavior and suppresses T{sub C}. However, at the same time, the quark-gluon vertex was shown not to modify the result at leading order. This dichotomy between the effects of the radiative corrections at first appears rather surprising, as the BRST identity connects the self-energy to the vertex corrections. Nevertheless, as we demonstrate, there is in fact no contradiction with the BRST identity, at least to leading logarithmic order. This clarifies some of the previous statements on the importance of the higher order corrections to the determination of T{sub C} and the zero temperature gap in color superconductivity. (c) 2000 The American Physical Society.

  20. Finite-temperature exact diagonalization cluster dynamical mean-field study of the two-dimensional Hubbard model: Pseudogap, non-Fermi-liquid behavior, and particle-hole asymmetry

    NASA Astrophysics Data System (ADS)

    Liebsch, Ansgar; Tong, Ning-Hua

    2009-10-01

    The effect of doping in the two-dimensional Hubbard model is studied within finite-temperature exact diagonalization combined with cluster dynamical mean-field theory. By employing a mixed basis involving cluster sites and bath molecular orbitals for the projection of the lattice Green’s function onto 2×2 clusters, a considerably more accurate description of the low-frequency properties of the self-energy is achieved than in a pure site picture. To evaluate the phase diagram, the transition from Fermi-liquid to non-Fermi-liquid behavior for decreasing hole doping is studied as a function of Coulomb energy, next-nearest-neighbor hopping, and temperature. The self-energy component ΣX associated with X=(π,0) is shown to develop a collective mode above EF , whose energy and strength exhibits a distinct dispersion with doping. This low-energy excitation gives rise to non-Fermi-liquid behavior as the hole doping decreases below a critical value δc , and to an increasing particle-hole asymmetry, in agreement with recent photoemission data. This behavior is consistent with the removal of spectral weight from electron states above EF and the opening of a pseudogap, which increases with decreasing doping. The phase diagram reveals that δc≈0.15…0.20 for various system parameters. For electron doping, the collective mode of ΣX(ω) and the concomitant pseudogap are located below the Fermi energy, which is consistent with the removal of spectral weight from the hole states just below EF . The critical doping, which marks the onset of non-Fermi-liquid behavior, is systematically smaller than for hole doping.

  1. Bosonization of the low energy excitations of Fermi liquids

    SciTech Connect

    Castro Neto, A.H.; Fradkin, E. )

    1994-03-07

    We bosonize the low energy excitations of Fermi liquids in any number of dimensions in the limit of long wavelengths. The bosons are a coherent superposition of electron-hole pairs and are related with the displacements of the Fermi surface in some arbitrary direction. A coherent-state path integral for the bosonized theory is derived and it is shown to represent histories of the shape of the Fermi surface. The Landau theory of Fermi liquids can be obtained from the formalism in the absence of nesting of the Fermi surface and singular interactions. We show that the Landau equation for sound waves is exact in the semiclassical approximation for the bosons.

  2. Superconductivity and Non-Fermi-Liquid Behavior in the Heavy-Fermion Compound CeCo1-xNixIn5

    NASA Astrophysics Data System (ADS)

    Otaka, Ryo; Yokoyama, Makoto; Mashiko, Hiroaki; Hasegawa, Takeshi; Shimizu, Yusei; Ikeda, Yoichi; Tenya, Kenichi; Nakamura, Shota; Ueta, Daichi; Yoshizawa, Hideki; Sakakibara, Toshiro

    2016-09-01

    The effect of off-plane impurity on superconductivity and non-Fermi-liquid (NFL) behavior in the layered heavy-fermion compound CeCo1-xNixIn5 is investigated by specific heat, magnetization, and electrical resistivity measurements. These measurements reveal that the superconducting (SC) transition temperature Tc monotonically decreases from 2.3 K (x = 0) to 0.8 K (x = 0.20) with increasing x, and then the SC order disappears above x = 0.25. At the same time, the Ni substitution yields the NFL behavior at zero field for x = 0.25, characterized by the -ln T divergence in specific heat divided by temperature, Cp/T, and magnetic susceptibility, M/B. The NFL behavior in magnetic fields for x = 0.25 is quite similar to that seen at around the SC upper critical field in pure CeCoIn5, suggesting that both compounds are governed by the same antiferromagnetic quantum criticality. The resemblance of the doping effect on the SC order among Ni-, Sn-, and Pt-substituted CeCoIn5 supports the argument that the doped carriers are primarily responsible for the breakdown of the SC order. The present investigation further reveals the quantitative differences in the trends of the suppression of superconductivity between Ce(Co,Ni)In5 and the other alloys, such as the rates of decrease in Tc, dTc/dx, and specific heat jump at Tc, d(ΔCp/Tc)/dx. We suggest that the occupied positions of the doped ions play an important role in the origin of these differences.

  3. Bosonic Analogue of Dirac Composite Fermi Liquid

    NASA Astrophysics Data System (ADS)

    Mross, David F.; Alicea, Jason; Motrunich, Olexei I.

    2016-09-01

    We introduce a particle-hole-symmetric metallic state of bosons in a magnetic field at odd-integer filling. This state hosts composite fermions whose energy dispersion features a quadratic band touching and corresponding 2 π Berry flux protected by particle-hole and discrete rotation symmetries. We also construct an alternative particle-hole symmetric state—distinct in the presence of inversion symmetry—without Berry flux. As in the Dirac composite Fermi liquid introduced by Son [Phys. Rev. X 5, 031027 (2015)], breaking particle-hole symmetry recovers the familiar Chern-Simons theory. We discuss realizations of this phase both in 2D and on bosonic topological insulator surfaces, as well as signatures in experiments and simulations.

  4. Field-induced quantum critical route to a Fermi liquid in high-temperature superconductors

    PubMed Central

    Shibauchi, Takasada; Krusin-Elbaum, Lia; Hasegawa, Masashi; Kasahara, Yuichi; Okazaki, Ryuji; Matsuda, Yuji

    2008-01-01

    In high-transition-temperature (Tc) superconductivity, charge doping is a natural tuning parameter that takes copper oxides from the antiferromagnet to the superconducting region. In the metallic state above Tc, the standard Landau's Fermi-liquid theory of metals as typified by the temperature squared (T2) dependence of resistivity appears to break down. Whether the origin of the non-Fermi-liquid behavior is related to physics specific to the cuprates is a fundamental question still under debate. We uncover a transformation from the non-Fermi-liquid state to a standard Fermi-liquid state driven not by doping but by magnetic field in the overdoped high-Tc superconductor Tl2Ba2CuO6+x. From the c-axis resistivity measured up to 45 T, we show that the Fermi-liquid features appear above a sufficiently high field that decreases linearly with temperature and lands at a quantum critical point near the superconductivity's upper critical field—with the Fermi-liquid coefficient of the T2 dependence showing a power-law diverging behavior on the approach to the critical point. This field-induced quantum criticality bears a striking resemblance to that in quasi-two-dimensional heavy-Fermion superconductors, suggesting a common underlying spin-related physics in these superconductors with strong electron correlations. PMID:18480261

  5. Heavy non-Fermi-liquid behavior in nearness to ferromagnetism in Th{sub 1{minus}x}U{sub x}Cu{sub 2}Si{sub 2}

    SciTech Connect

    Lenkewitz, M.; Corsepius, S.; Blanckenhagen, G.v.; Stewart, G.R.

    1997-03-01

    Th{sub 1{minus}x}U{sub x}Cu{sub 2}Si{sub 2} compounds have been investigated by means of specific heat, susceptibility, magnetization, and resistivity measurements. Samples with x{ge}0.15 are ferromagnetic. Th{sub 0.85}U{sub 0.15}Cu{sub 2}Si{sub 2} and Th{sub 0.8}U{sub 0.2}Cu{sub 2}Si{sub 2} show enhanced values for C/T at low temperatures ({approx}460 mJ/UmolK{sup 2} for x=0.2). The specific heat of samples that exhibit no long-range order (x{le}0.1) can be described by C/T{proportional_to}{minus}ln(T). This divergence is characteristic of non-Fermi-liquid (nFl) systems. The results are discussed in regard to the current investigations on non-Fermi liquids. One interpretation of non-Fermi-liquid behavior is a T=0 instability in nearness to magnetism. Our data indicate that this is a system that displays C/T{proportional_to}lnT near to ferromagnetism. {copyright} {ital 1997} {ital The American Physical Society}

  6. A Fermi liquid theory of mixed-valence systems

    NASA Astrophysics Data System (ADS)

    Lin, Zonghan; Tsung-han, Lin; Liu, Fu-sui

    1985-06-01

    The local non-interacting Fermi liquid theory of Newns and Hewson is extended to include the interaction by introducing a molecular field parameter. The zero-temperature susceptibility and linear coefficient of specific heat are calculated.

  7. Spin waves in a persistent spin-current Fermi liquid

    SciTech Connect

    Feldmann, J. D.; Bedell, K. S.

    2010-06-15

    We report two theoretical results for transverse spin waves, which arise in a system with a persistent spin current. Using Fermi liquid theory, we introduce a spin current in the ground state of a polarized or unpolarized Fermi liquid, and we derive the resultant spin waves using the Landau kinetic equation. The resulting spin waves have a q{sup 1} and q{sup 1/2} dispersion to leading order for the polarized and unpolarized systems, respectively.

  8. Non-Fermi liquid phase in metallic Skyrmion crystals

    NASA Astrophysics Data System (ADS)

    Watanabe, Haruki; Parameswaran, Siddharth; Raghu, Srinivas; Vishwanath, Ashvin

    2014-03-01

    Motivated by reports of a non-Fermi liquid state in MnSi, we examine the effect of coupling phonons of an incommensurate skyrmion crystal (SkX) to conduction electrons. We find that non-Fermi liquid behavior emerges in both two and three dimensions over the entire phase, due to an anomalous electron-phonon coupling that is linked to the net skyrmion density. A small parameter, the spiral wave vector in lattice units, allows us to exercise analytic control and ignore Landau damping of phonons over a wide energy range. At the lowest energy scales the problem is similar to electrons coupled to a gauge field. The best prospects for realizing these effects is in short period skyrmion lattice systems such as MnGe or epitaxial MnSi films. We also compare our results with the unusual T 3 / 2 scaling of temperature dependent resistivity seen in high pressure experiments on MnSi. We acknowledge support from the NSF via Grant DMR-0645691, the DOE Office of Basic Energy Sciences via contract DE-AC02-76SF00515, and the Simons, Templeton, and Alfred P. Sloan Foundations.

  9. Hidden Fermi liquid, scattering rate saturation, and Nernst effect: a dynamical mean-field theory perspective.

    PubMed

    Xu, Wenhu; Haule, Kristjan; Kotliar, Gabriel

    2013-07-19

    We investigate the transport properties of a correlated metal within dynamical mean-field theory. Canonical Fermi liquid behavior emerges only below a very low temperature scale T(FL). Surprisingly the quasiparticle scattering rate follows a quadratic temperature dependence up to much higher temperatures and crosses over to saturated behavior around a temperature scale T(sat). We identify these quasiparticles as constituents of the hidden Fermi liquid. The non-Fermi-liquid transport above T(FL), in particular the linear-in-T resistivity, is shown to be a result of a strongly temperature dependent band dispersion. We derive simple expressions for the resistivity, Hall angle, thermoelectric power and Nernst coefficient in terms of a temperature dependent renormalized band structure and the quasiparticle scattering rate. We discuss possible tests of the dynamical mean-field theory picture of transport using ac measurements. PMID:23909344

  10. Hidden Fermi liquid, scattering rate saturation, and Nernst effect: a dynamical mean-field theory perspective.

    PubMed

    Xu, Wenhu; Haule, Kristjan; Kotliar, Gabriel

    2013-07-19

    We investigate the transport properties of a correlated metal within dynamical mean-field theory. Canonical Fermi liquid behavior emerges only below a very low temperature scale T(FL). Surprisingly the quasiparticle scattering rate follows a quadratic temperature dependence up to much higher temperatures and crosses over to saturated behavior around a temperature scale T(sat). We identify these quasiparticles as constituents of the hidden Fermi liquid. The non-Fermi-liquid transport above T(FL), in particular the linear-in-T resistivity, is shown to be a result of a strongly temperature dependent band dispersion. We derive simple expressions for the resistivity, Hall angle, thermoelectric power and Nernst coefficient in terms of a temperature dependent renormalized band structure and the quasiparticle scattering rate. We discuss possible tests of the dynamical mean-field theory picture of transport using ac measurements.

  11. String theory, quantum phase transitions, and the emergent Fermi liquid.

    PubMed

    Cubrović, Mihailo; Zaanen, Jan; Schalm, Koenraad

    2009-07-24

    A central problem in quantum condensed matter physics is the critical theory governing the zero-temperature quantum phase transition between strongly renormalized Fermi liquids as found in heavy fermion intermetallics and possibly in high-critical temperature superconductors. We found that the mathematics of string theory is capable of describing such fermionic quantum critical states. Using the anti-de Sitter/conformal field theory correspondence to relate fermionic quantum critical fields to a gravitational problem, we computed the spectral functions of fermions in the field theory. By increasing the fermion density away from the relativistic quantum critical point, a state emerges with all the features of the Fermi liquid.

  12. Breakdown of the Fermi Liquid Description for Strongly Interacting Fermions

    NASA Astrophysics Data System (ADS)

    Sagi, Yoav; Drake, Tara E.; Paudel, Rabin; Chapurin, Roman; Jin, Deborah S.

    2015-02-01

    The nature of the normal state of an ultracold Fermi gas in the BCS-BEC crossover regime is an intriguing and controversial topic. While the many-body ground state remains a condensate of paired fermions, the normal state must evolve from a Fermi liquid to a Bose gas of molecules as a function of the interaction strength. How this occurs is still largely unknown. We explore this question with measurements of the distribution of single-particle energies and momenta in a nearly homogeneous gas above Tc . The data fit well to a function that includes a narrow, positively dispersing peak that corresponds to quasiparticles and an "incoherent background" that can accommodate broad, asymmetric line shapes. We find that the quasiparticle's spectral weight vanishes abruptly as the strength of interactions is modified, which signals the breakdown of a Fermi liquid description. Such a sharp feature is surprising in a crossover.

  13. Fermi Liquid Instabilities in the Spin Channel

    SciTech Connect

    Wu, Congjun; Sun, Kai; Fradkin, Eduardo; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

    2010-03-16

    We study the Fermi surface instabilities of the Pomeranchuk type in the spin triplet channel with high orbital partial waves (F{sub l}{sup a} (l > 0)). The ordered phases are classified into two classes, dubbed the {alpha} and {beta}-phases by analogy to the superfluid {sup 3}He-A and B-phases. The Fermi surfaces in the {alpha}-phases exhibit spontaneous anisotropic distortions, while those in the {beta}-phases remain circular or spherical with topologically non-trivial spin configurations in momentum space. In the {alpha}-phase, the Goldstone modes in the density channel exhibit anisotropic overdamping. The Goldstone modes in the spin channel have nearly isotropic underdamped dispersion relation at small propagating wavevectors. Due to the coupling to the Goldstone modes, the spin wave spectrum develops resonance peaks in both the {alpha} and {beta}-phases, which can be detected in inelastic neutron scattering experiments. In the p-wave channel {beta}-phase, a chiral ground state inhomogeneity is spontaneously generated due to a Lifshitz-like instability in the originally nonchiral systems. Possible experiments to detect these phases are discussed.

  14. Fermi liquid parameters of a 2D 3He film

    NASA Astrophysics Data System (ADS)

    Lusher, C. P.; Saunders, J.; Cowan, B. P.

    1990-08-01

    A temperature independent magnetic susceptibility has been observed for the second layer of 3He on graphite for second layer surface densities less than 0.055 Å -2, consistent with 2D Fermi liquid behaviour. The Landau parameter Foa is determined using known values of m ∗/m. The relative dependence of these two parameters is in good agreement with almost localised Fermion theory, as is the case in bulk liquid 3He.

  15. Non-Fermi liquids in two and three-dimensional doped SrTiO3

    NASA Astrophysics Data System (ADS)

    Mikheev, Evgeny; Raghavan, Santosh; Zhang, Jack; Marshall, Patrick; Kajdos, Adam; Balents, Leon; Stemmer, Susanne

    A remarkable feature of transport in doped SrTiO3 is the temperature dependence of the electrical resistivity that is proportional to Tn with n <= 2. This power law suggests electron-electron scattering is the dominant scattering mechanism. It extends to room temperature and above in both three-dimensional, uniformly doped SrTiO3 and in two-dimensional electron liquids (2DELs) at oxide interfaces. In case of n = 2, the behavior is traditionally identified as that of a Landau Fermi liquid. Here we argue that Landau Fermi liquid theory does not apply to the electron liquid in SrTiO3, even when n = 2. Using electrostatic gating and chemical doping, we demonstrate that this regime is associated with a scattering rate and an energy scale that are independent of carrier density. This is in fundamental conflict with the premise of the Fermi liquid theory, where this energy scale is the Fermi energy. This work raises important questions in terms of microscopic scattering mechanism. It appears to be relevant for understanding of transport in many other strongly correlated systems, which also show very robust Tn regimes with carrier density independent scattering rates.

  16. Magnetic field-tuned Fermi liquid formation in Mn0.75 Fe0.25 Si

    NASA Astrophysics Data System (ADS)

    Samatham, S. Shanmukharao; Yadam, Sankararao; Singh, Durgesh; Ganesan, V.

    2016-11-01

    Low temperature ground state properties of Mn0.75 Fe0.25 Si are investigated based on temperature and magnetic field dependent behavior of specific heat and resistivity. Paramagnon spin fluctuations assisted non-Fermi liquid is suppressed by magnetic fields and gradual evolution of Fermi liquid is demonstrated. The tendency of magnetic field-induced crossover from non-Fermi to Fermi liquid behavior is illustrated by suitable magneto-specific heat scaling which reveals unusual quantum critical phenomenon in a 3d transition metal derived paramagnetic compound. In the absence of magnetic fields, Kadowaki-Wood's Ratio (KWR) A /γ2 is about 8.5 μΩcmmol2K2J-2 which is 85% close to the originally proposed KWR and reaches 100% under the moderate magnetic fields of 0.7 T.

  17. Fractionalized Fermi liquid in a Kondo-Heisenberg model

    NASA Astrophysics Data System (ADS)

    Tsvelik, A. M.

    2016-10-01

    The Kondo-Heisenberg model is used as a controllable tool to demonstrate the existence of a peculiar metallic state with unbroken translational symmetry where the Fermi surface volume is not controlled by the total electron density. I use a nonperturbative approach where the strongest interactions are taken into account by means of exact solution, and corrections are controllable. In agreement with the general requirements formulated by T. Senthil et al. [Phys. Rev. Lett. 90, 216403 (2003), 10.1103/PhysRevLett.90.216403], the resulting metallic state represents a fractionalized Fermi liquid where well defined quasiparticles coexist with gapped fractionalized collective excitations. The system undergoes a phase transition to an ordered phase (charge density wave or superconducting), at the transition temperature which is parametrically small in comparison to the quasiparticle Fermi energy.

  18. Optical spectroscopy shows that the normal state of URu2Si2 is an anomalous Fermi liquid.

    PubMed

    Nagel, Urmas; Uleksin, Taaniel; Rõõm, Toomas; Lobo, Ricardo P S M; Lejay, Pascal; Homes, Christopher C; Hall, Jesse S; Kinross, Alison W; Purdy, Sarah K; Munsie, Tim; Williams, Travis J; Luke, Graeme M; Timusk, Thomas

    2012-11-20

    Fermi showed that, as a result of their quantum nature, electrons form a gas of particles whose temperature and density follow the so-called Fermi distribution. As shown by Landau, in a metal the electrons continue to act like free quantum mechanical particles with enhanced masses, despite their strong Coulomb interaction with each other and the positive background ions. This state of matter, the Landau-Fermi liquid, is recognized experimentally by an electrical resistivity that is proportional to the square of the absolute temperature plus a term proportional to the square of the frequency of the applied field. Calculations show that, if electron-electron scattering dominates the resistivity in a Landau-Fermi liquid, the ratio of the two terms, b, has the universal value of b = 4. We find that in the normal state of the heavy Fermion metal URu(2)Si(2), instead of the Fermi liquid value of 4, the coefficient b = 1 ± 0.1. This unexpected result implies that the electrons in this material are experiencing a unique scattering process. This scattering is intrinsic and we suggest that the uranium f electrons do not hybridize to form a coherent Fermi liquid but instead act like a dense array of elastic impurities, interacting incoherently with the charge carriers. This behavior is not restricted to URu(2)Si(2). Fermi liquid-like states with b ≠ 4 have been observed in a number of disparate systems, but the significance of this result has not been recognized.

  19. Optical spectroscopy shows that the normal state of URu2Si2 is an anomalous Fermi liquid

    PubMed Central

    Nagel, Urmas; Uleksin, Taaniel; Rõõm, Toomas; Lobo, Ricardo P. S. M.; Lejay, Pascal; Homes, Christopher C.; Hall, Jesse S.; Kinross, Alison W.; Purdy, Sarah K.; Munsie, Tim; Williams, Travis J.; Luke, Graeme M.; Timusk, Thomas

    2012-01-01

    Fermi showed that, as a result of their quantum nature, electrons form a gas of particles whose temperature and density follow the so-called Fermi distribution. As shown by Landau, in a metal the electrons continue to act like free quantum mechanical particles with enhanced masses, despite their strong Coulomb interaction with each other and the positive background ions. This state of matter, the Landau–Fermi liquid, is recognized experimentally by an electrical resistivity that is proportional to the square of the absolute temperature plus a term proportional to the square of the frequency of the applied field. Calculations show that, if electron-electron scattering dominates the resistivity in a Landau–Fermi liquid, the ratio of the two terms, b, has the universal value of b = 4. We find that in the normal state of the heavy Fermion metal URu2Si2, instead of the Fermi liquid value of 4, the coefficient b = 1 ± 0.1. This unexpected result implies that the electrons in this material are experiencing a unique scattering process. This scattering is intrinsic and we suggest that the uranium f electrons do not hybridize to form a coherent Fermi liquid but instead act like a dense array of elastic impurities, interacting incoherently with the charge carriers. This behavior is not restricted to URu2Si2. Fermi liquid-like states with b ≠ 4 have been observed in a number of disparate systems, but the significance of this result has not been recognized. PMID:23115333

  20. Magnetically robust non-fermi liquid behavior due to the competition between crystalline-electric field singlet and Kondo-Yosida singlet in f2-based heavy fermion systems

    NASA Astrophysics Data System (ADS)

    Nishiyama, Shinya; Matsuura, Hiroyasu; Miyake, Kazumasa

    2011-01-01

    In f2-based heavy fermion systems with a tetragonal symmetry, we investigate the magnetic field dependence of a non-fermi liquid (NFL) which arises related to the quantum critical point (QCP) due to the competition between the crystalline-electric field (CEF) singlet and the Kondo-Yosida singlet states. On the basis of the Wilson numerical renormalization group method, we find that the magnetic field less than a characteristic magnetic field Hz* does not affect the characteristic temperature TF* at which the specific heat takes a maximum value. Since such Hz* increases as the deviation from the QCP increases, slightly off the QCP, there are parameter regions where NFL behaviors are robust at an observable temperature range T > TF*against a magnetic field of up to Hz* which is far larger than TF*. Our result suggests that such robust NFL behaviors can arise also in systems with other CEF symmetries; e.g., magnetically robust NFL behaviors observed in UBe13 may be understood on this basis.

  1. Spin Waves and Spin Relaxation in Normal Fermi Liquids.

    NASA Astrophysics Data System (ADS)

    Meltzer, David Elliott

    This work explores several aspects of spin-dependent excitations in normal Fermi liquids. Chapter 1 is a general introduction and overview of the work. The Landau kinetic equation and its application to nonequilibrium proper- ties of Fermi liquids is discussed, and the properties of collective density modes are briefly reviewed. The properties of both longitu- dinal and transverse spin excitations are then outlined, leading up to a discussion of spin waves and spin diffusion, including the Leggett -Rice effect. Chapter 2 discusses the possibility of making a determination of the contribution of many-body interactions to the large effective mass in "heavy-fermion" materials, e.g. UPt(,3), by the method of conduction-electron spin resonance (CESR). It is shown that a microwave trans- mission observation of CESR might show a resonance pattern which, based on already measured parameters, would clearly distinguish among various suggested models for the strength of the many-body effects. Chapter 3 investigates the accuracy of the usual relaxation time approximations, involving the spin diffusion lifetime (tau)(,D), which are generally made in analyses of spin waves and the Leggett-Rice effect in Fermi liquids. By employing the variational methods of Ah-Sam, H(SLASHCIRC)jgaard -Jensen and Smith, and Egilsson and Pethick, we are able to determine upper and lower bounds on the effective diffusion coefficient resulting from spin wave phenomena which are accurate in the whole Fermi liquid regime. Our results indicate that the usual approximations break down for(' )T < 7 mK in ('3)He, but are accurate to within (TURN)2% in 5% ('3)He-('4)He mixtures. Chapter 4 contains a calculation of the longitudinal spin relaxa- tion time T(,1) in bulk ('3)He in the Fermi liquid (T << T(,F)) regime. The kinetic equation is used to obtain an expression for T(,1) in terms of perturbations of the scattering amplitude. These perturbations are then obtained using the induced interaction model

  2. Towards a Holographic Marginal Fermi Liquid

    SciTech Connect

    Jensen, Kristan; Kachru, Shamit; Karch, Andreas; Polchinski, Joseph; Silverstein, Eva

    2011-08-15

    We present an infinite class of 2+1 dimensional field theories which, after coupling to semi-holographic fermions, exhibit strange metallic behavior in a suitable large N limit. These theories describe lattices of hypermultiplet defects interacting with parity-preserving supersymmetric Chern-Simons theories with U(N) x U(N) gauge groups at levels {+-}k. They have dual gravitational descriptions in terms of lattices of probe M2 branes in AdS{sub 4} x S{sup 7}/Z{sub k} (for N >> 1,N >> k{sup 5}) or probe D2 branes in AdS{sub 4} x CP{sup 3} (for N >> k >> 1,N << k{sup 5}). We discuss several challenges one faces in maintaining the success of these models at finite N, including backreaction of the probes in the gravity solutions and radiative corrections in the weakly coupled field theory limit.

  3. Stable non-Fermi-liquid phase of itinerant spin-orbit coupled ferromagnets

    NASA Astrophysics Data System (ADS)

    Bahri, Yasaman; Potter, Andrew C.

    2015-07-01

    Direct (nongradient) coupling between a gapless bosonic field and a Fermi surface results in the destruction of Landau quasiparticles and a breakdown of Fermi liquid theory. Such a non-Fermi-liquid phase arises in spin-orbit coupled ferromagnets with spontaneously broken continuous symmetries due to strong coupling between rotational Goldstone modes and itinerant electrons. These systems provide an experimentally accessible context for studying non-Fermi-liquid physics. Possible examples include low-density Rashba coupled electron gases, which have a natural tendency towards spontaneous ferromagnetism, or topological insulator surface states with proximity-induced ferromagnetism. Crucially, unlike the related case of a spontaneous nematic distortion of the Fermi surface, for which controlled field theory calculations predict that the non-Fermi-liquid regime will be masked by a superconducting dome, we show that the non-Fermi-liquid phase in spin-orbit coupled ferromagnets is stable.

  4. Momentum-resolved spectroscopy of a Fermi liquid.

    PubMed

    Doggen, Elmer V H; Kinnunen, Jami J

    2015-01-01

    We consider a recent momentum-resolved radio-frequency spectroscopy experiment, in which Fermi liquid properties of a strongly interacting atomic Fermi gas were studied. Here we show that by extending the Brueckner-Goldstone model, we can formulate a theory that goes beyond basic mean-field theories and that can be used for studying spectroscopies of dilute atomic gases in the strongly interacting regime. The model hosts well-defined quasiparticles and works across a wide range of temperatures and interaction strengths. The theory provides excellent qualitative agreement with the experiment. Comparing the predictions of the present theory with the mean-field Bardeen-Cooper-Schrieffer theory yields insights into the role of pair correlations, Tan's contact, and the Hartree mean-field energy shift. PMID:25941948

  5. Degenerate Fermi and non-Fermi liquids near a quantum critical phase transition

    NASA Astrophysics Data System (ADS)

    Kambe, S.; Sakai, H.; Tokunaga, Y.; Lapertot, G.; Matsuda, T. D.; Knebel, G.; Flouquet, J.; Walstedt, R. E.

    2014-11-01

    Recently there is renewed interest in quantum critical phase transitions (QCPT) at T = 0 K in metallic strongly correlated electron systems. From early experimental results, the QCPT in the Kondo-lattice compound YbRh2Si2 is not a case of the ordinary spin density wave (SDW) instability observed in Ce-based Kondo lattices, but a candidate for a novel locally critical case. Here, we observe that coexisting, static Fermi liquid (FL) and non-Fermi liquid (NFL) states are a key feature of the QCPT in YbRh2Si2. By means of nuclear magnetic resonance (NMR) spin-lattice relaxation time (T1) measurements on a single-crystalline sample, we find that the FL and NFL states are invariant, whereas their ratio in a crossover is field dependent near the QCPT. Such a pair of states has remained hidden in Ce compounds, owing presumably to the short lifetimes of the two states. We derive a scaling law for the occupation ratio of the two states, which could be widely applicable to Kondo-lattice systems.

  6. Incoherence-coherence crossover and low-temperature Fermi-liquid-like behavior in AFe2As2 (A  =  K, Rb, Cs): evidence from electrical transport properties.

    PubMed

    Xiang, Z J; Wang, N Z; Wang, A F; Zhao, D; Sun, Z L; Luo, X G; Wu, T; Chen, X H

    2016-10-26

    We study the normal-state transport properties of AFe2As2 (A  =  K, Rb and Cs) single crystals using Hall coefficient, resistivity and magnetoresistance (MR) measurements. In all three materials, the Hall coefficient R H shows a strong temperature dependence, which is typical for multi-band systems. In particular, R H develops an upturn below a characteristic temperature [Formula: see text], which is in agreement with the incoherence-coherence crossover reported in recent nuclear magnetic resonance studies. A Fermi-liquid-like state, characterized by T (2) behavior of the resistivity and a positive orbital MR obeying Kohler's rule, emerges below T FL  ∼0.4 [Formula: see text]. The superconducting transition temperature T c experiences a simultaneous suppression with [Formula: see text] and T FL as the alkali ion's radius increases from A  =  K to A  =  Cs, suggesting that the unconventional superconductivity in the AFe2As2 series is related to the strength of the electronic coherence. A phase diagram, similar to that in the heavy fermion Kondo lattice system, is obtained. Based on all the experimental evidence, we argue that the physical properties of this family of heavily hole-doped Fe-based superconductors are controlled by the hybridization between itinerant carriers and localized orbitals, and the Kondo scenario could be effective in such a case.

  7. Incoherence-coherence crossover and low-temperature Fermi-liquid-like behavior in AFe2As2 (A  =  K, Rb, Cs): evidence from electrical transport properties

    NASA Astrophysics Data System (ADS)

    Xiang, Z. J.; Wang, N. Z.; Wang, A. F.; Zhao, D.; Sun, Z. L.; Luo, X. G.; Wu, T.; Chen, X. H.

    2016-10-01

    We study the normal-state transport properties of AFe2As2 (A  =  K, Rb and Cs) single crystals using Hall coefficient, resistivity and magnetoresistance (MR) measurements. In all three materials, the Hall coefficient R H shows a strong temperature dependence, which is typical for multi-band systems. In particular, R H develops an upturn below a characteristic temperature {{T}\\ast} , which is in agreement with the incoherence-coherence crossover reported in recent nuclear magnetic resonance studies. A Fermi-liquid-like state, characterized by T 2 behavior of the resistivity and a positive orbital MR obeying Kohler’s rule, emerges below T FL  ˜0.4 ~{{T}\\ast} . The superconducting transition temperature T c experiences a simultaneous suppression with {{T}\\ast} and T FL as the alkali ion’s radius increases from A  =  K to A  =  Cs, suggesting that the unconventional superconductivity in the AFe2As2 series is related to the strength of the electronic coherence. A phase diagram, similar to that in the heavy fermion Kondo lattice system, is obtained. Based on all the experimental evidence, we argue that the physical properties of this family of heavily hole-doped Fe-based superconductors are controlled by the hybridization between itinerant carriers and localized orbitals, and the Kondo scenario could be effective in such a case.

  8. Incoherence-coherence crossover and low-temperature Fermi-liquid-like behavior in AFe2As2 (A  =  K, Rb, Cs): evidence from electrical transport properties.

    PubMed

    Xiang, Z J; Wang, N Z; Wang, A F; Zhao, D; Sun, Z L; Luo, X G; Wu, T; Chen, X H

    2016-10-26

    We study the normal-state transport properties of AFe2As2 (A  =  K, Rb and Cs) single crystals using Hall coefficient, resistivity and magnetoresistance (MR) measurements. In all three materials, the Hall coefficient R H shows a strong temperature dependence, which is typical for multi-band systems. In particular, R H develops an upturn below a characteristic temperature [Formula: see text], which is in agreement with the incoherence-coherence crossover reported in recent nuclear magnetic resonance studies. A Fermi-liquid-like state, characterized by T (2) behavior of the resistivity and a positive orbital MR obeying Kohler's rule, emerges below T FL  ∼0.4 [Formula: see text]. The superconducting transition temperature T c experiences a simultaneous suppression with [Formula: see text] and T FL as the alkali ion's radius increases from A  =  K to A  =  Cs, suggesting that the unconventional superconductivity in the AFe2As2 series is related to the strength of the electronic coherence. A phase diagram, similar to that in the heavy fermion Kondo lattice system, is obtained. Based on all the experimental evidence, we argue that the physical properties of this family of heavily hole-doped Fe-based superconductors are controlled by the hybridization between itinerant carriers and localized orbitals, and the Kondo scenario could be effective in such a case. PMID:27589485

  9. Spin response of a normal Fermi liquid with noncentral interactions

    SciTech Connect

    Pethick, C. J.; Schwenk, A.

    2009-11-15

    We consider the spin response of a normal Fermi liquid with noncentral interactions under conditions intermediate between the collisionless and hydrodynamic regimes. This problem is of importance for calculations of neutrino properties in dense matter. By expressing the deviation of the quasiparticle distribution function from equilibrium in terms of eigenfunctions of the transport equation under the combined influence of collisions and an external field, we derive a closed expression for the spin-density-spin-density response function and compare its predictions with that of a relaxation-time approximation. Our results indicate that the relaxation-time approximation is reliable for neutrino properties under astrophysically relevant conditions.

  10. The 2d MIT: The Pseudogap and Fermi Liquid Theory

    NASA Astrophysics Data System (ADS)

    Castner, T. G.

    2005-06-01

    Fermi liquid theory for the 2d metal-insulator transition is extended to include the correlation gap in the density-of-states. The results are consistent with the scaling form g=gce[on(To/T)] at T larger than a characteristic T* ∝ xTc (Tc=Ec= mobility edge). The two-component model n1+nloc=n=nc(1+x) for n>nc is required and the theory explains the T-dependence of the data of Hanein et al. for p-type GaAs.

  11. Spectral function and kinetic equation for a normal Fermi liquid

    SciTech Connect

    Arshad, M.; Siddique, I.; Kondratyev, A. S.

    2007-08-01

    On the basis of the Kadanoff-Baym (KB) version of the time-dependent Green's function method, an Ansatz for the approximation of a spectral function is offered. The Ansatz possesses all the advantages of quasiparticle and extended quasiparticle approximations and satisfies the KB equation for a spectral function in the case of slightly nonequilibrium system when disturbances in space and time are taken into consideration in the gradient approximation. This feature opens opportunities for the microscopic derivation of the Landau kinetic equation for the quasiparticle distribution function of the normal Fermi liquid and provides the widening of these equations' temperature range of validity.

  12. Two-component Fermi-liquid theory - Equilibrium properties of liquid metallic hydrogen

    NASA Technical Reports Server (NTRS)

    Oliva, J.; Ashcroft, N. W.

    1981-01-01

    It is reported that the transition of condensed hydrogen from an insulating molecular crystal phase to a metallic liquid phase, at zero temperature and high pressure, appears possible. Liquid metallic hydrogen (LMH), comprising interpenetrating proton and electron fluids, would constitute a two-component Fermi liquid with both a very high component-mass ratio and long-range, species-dependent bare interactions. The low-temperature equilibrium properties of LMH are examined by means of a generalization to the case of two components of the phenomenological Landau Fermi-liquid theory, and the low-temperature specific heat, compressibility, thermal expansion coefficient and spin susceptibility are given. It is found that the specific heat and the thermal expansion coefficient are vastly greater in the liquid than in the corresponding solid, due to the presence of proton quasiparticle excitations in the liquid.

  13. Kondo disorder and non-Fermi-liquid behavior in UCu{sub 5{minus}{ital x}}Pd{sub {ital x}} and CeCu{sub 5.9}Au{sub 0.1}

    SciTech Connect

    Bernal, O.O.; MacLaughlin, D.E.; Amato, A.; Feyerherm, R.; Gygax, F.N.; Schenck, A.; Heffner, R.H.; Le, L.P.; Nieuwenhuys, G.J.; Andraka, B.; Loehneysen, H.v.; Stockert, O.; Ott, H.R.

    1996-11-01

    Muon spin rotation ({mu}SR) has been used to probe non-Fermi-liquid (NFL) behavior in the heavy-fermion alloys UCu{sub 5{minus}{ital x}}Pd{sub {ital x}}, {ital x}=1.0 and 1.5, and CeCu{sub 5.9}Au{sub 0.1}. Zero-field {mu}SR puts an upper bound of {approximately}0.01{mu}{sub {ital B}}/{ital U} atom on any static magnetism in UCu{sub 5{minus}{ital x}}Pd{sub {ital x}}, which is too weak to affect the transverse-field {mu}SR linewidth or to give rise to NFL behavior. In agreement with NMR results, {mu}SR spectra in transverse fields suggest that a broad distribution of Kondo temperatures ({open_quote}{open_quote}Kondo disorder{close_quote}{close_quote}) is important in UCu{sub 5{minus}{ital x}}Pd{sub {ital x}}. NFL anomalies at temperature {ital T} then arise from {open_quote}{open_quote}free{close_quote}{close_quote} spins for which {ital T}{sub {ital K}}{lt}{ital T}. Comparison of {mu}SR and NMR linewidths also indicates short-range spatial correlation of the Kondo disorder in UCu{sub 5{minus}{ital x}}Pd{sub {ital x}}, in agreement with the local character of the dynamic susceptibility inferred from neutron scattering experiments. In CeCu{sub 5.9}Au{sub 0.1} the data suggest significant Kondo disorder only if the spatial correlation is long ranged, which is not indicated by other properties of this alloy. {copyright} {ital 1996 The American Physical Society.}

  14. Appearance of "fragile" Fermi liquids in finite-width Mott insulators sandwiched between metallic leads.

    PubMed

    Zenia, H; Freericks, J K; Krishnamurthy, H R; Pruschke, Th

    2009-09-11

    Using inhomogeneous dynamical mean-field theory, we show that the normal-metal proximity effect could force any finite number of Mott-insulating "barrier" planes sandwiched between semi-infinite metallic leads to become "fragile" Fermi liquids. They are fully Fermi-liquid-like at T=0, leading to a restoration of lattice periodicity at zero frequency, with a well-defined Fermi surface, and perfect (ballistic) conductivity. However, the Fermi-liquid character can rapidly disappear at finite omega, V, T, disorder, or magnetism, all of which restore the expected quantum tunneling regime, leading to fascinating possibilities for nonlinear response in devices.

  15. Interface Superconductivity in Cuprates Defies Fermi-Liquid Description

    DOE PAGES

    Radović, Zoran; Vanević, Mihajlo; Wu, Jie; Bollinger, Anthony T.; Božović, Ivan

    2016-07-26

    La2-xSrxCuO4/La2CuO4 bilayers show interface superconductivity that originates from accumulation and depletion of mobile charge carriers across the interface. Surprisingly, the doping level can be varied broadly (within the interval 0.15 < x < 0.47) without affecting the transition temperature, which stays essentially constant and equal to that in optimally doped material, Tc ≈ 40 K. Here we argue that this finding implies that doping up to the optimum level does not shift the chemical potential, unlike in ordinary Fermi liquids. Lastly, we discuss possible physical scenarios that can give doping-independent chemical potential in the pseudogap regime: electronic phase separation, formationmore » of charge-density waves, strong Coulomb interactions, or self-trapping of mobile charge carriers.« less

  16. Emergent Non-Fermi-Liquid at the Quantum Critical Point of a Topological Phase Transition in Two Dimensions.

    PubMed

    Isobe, Hiroki; Yang, Bohm-Jung; Chubukov, Andrey; Schmalian, Jörg; Nagaosa, Naoto

    2016-02-19

    We study the effects of Coulomb interaction between 2D Weyl fermions with anisotropic dispersion which displays relativistic dynamics along one direction and nonrelativistic dynamics along the other. Such a dispersion can be realized in phosphorene under electric field or strain, in TiO_{2}/VO_{2} superlattices, and, more generally, at the quantum critical point between a nodal semimetal and an insulator in systems with a chiral symmetry. Using the one-loop renormalization group approach in combination with the large-N expansion, we find that the system displays interaction-driven non-Fermi liquid behavior in a wide range of intermediate frequencies and marginal Fermi liquid behavior at the smallest frequencies. In the non-Fermi liquid regime, the quasiparticle residue Z at energy E scales as Z∝E^{a} with a>0, and the parameters of the fermionic dispersion acquire anomalous dimensions. In the marginal Fermi-liquid regime, Z∝(|logE|)^{-b} with universal b=3/2. PMID:26943551

  17. Few cycle pulses in semi-holographic Fermi liquid with impurities

    NASA Astrophysics Data System (ADS)

    Belonenko, Mikhail B.; Konobeeva, Natalia N.; Galkina, Elena N.

    2016-03-01

    Special aspects of few cycle pulses propagation in semi-holographic Fermi liquid with impurities are considered in this paper. Green’s function poles which are in charge of excitation states dispersion law of the liquid under consideration were given according to the ADS/CFT correspondence. The impact of both Fermi liquid parameters and its impurities on the few cycle pulse shape was defined.

  18. Universal Fermi liquid crossover and quantum criticality in a mesoscopic system.

    PubMed

    Keller, A J; Peeters, L; Moca, C P; Weymann, I; Mahalu, D; Umansky, V; Zaránd, G; Goldhaber-Gordon, D

    2015-10-01

    Quantum critical systems derive their finite-temperature properties from the influence of a zero-temperature quantum phase transition. The paradigm is essential for understanding unconventional high-Tc superconductors and the non-Fermi liquid properties of heavy fermion compounds. However, the microscopic origins of quantum phase transitions in complex materials are often debated. Here we demonstrate experimentally, with support from numerical renormalization group calculations, a universal crossover from quantum critical non-Fermi liquid behaviour to distinct Fermi liquid ground states in a highly controllable quantum dot device. Our device realizes the non-Fermi liquid two-channel Kondo state, based on a spin-1/2 impurity exchange-coupled equally to two independent electronic reservoirs. On detuning the exchange couplings we observe the Fermi liquid scale T*, at energies below which the spin is screened conventionally by the more strongly coupled channel. We extract a quadratic dependence of T* on gate voltage close to criticality, and validate an asymptotically exact description of the universal crossover between strongly correlated non-Fermi liquid and Fermi liquid states. PMID:26450057

  19. Diagrammatic λ series for extremely correlated Fermi liquids

    NASA Astrophysics Data System (ADS)

    Perepelitsky, Edward; Sriram Shastry, B.

    2015-06-01

    The recently developed theory of extremely correlated Fermi liquids (ECFL), applicable to models involving the physics of Gutzwiller projected electrons, shows considerable promise in understanding the phenomena displayed by the t- J model. Its formal equations for the Greens function are reformulated by a new procedure that is intuitively close to that used in the usual Feynman-Dyson theory. We provide a systematic procedure by which one can draw diagrams for the λ-expansion of the ECFL introduced in Shastry (2011), where the parameter λ ∈(0 , 1) counts the order of the terms. In contrast to the Schwinger method originally used for this problem, we are able to write down the nth order diagrams (O(λn)) directly with the appropriate coefficients, without enumerating all the previous order terms. This is a considerable advantage since it thereby enables the possible implementation of Monte Carlo methods to evaluate the λ series directly. The new procedure also provides a useful and intuitive alternative to the earlier methods.

  20. Un-Fermi Liquids: Unparticles in Strongly Correlated Electron Matter

    NASA Astrophysics Data System (ADS)

    Langley, Brandon; Phillips, Philip; Hutasoit, Jimmy

    2014-03-01

    Since any non-trivial infrared dynamics in strongly correlated electron matter must be controlled by a critical fixed point, we argue that the form of the single-particle propagator can be deduced simply by imposing scale invariance. As a consequence, the unparticle picture proposed by Georgi is the natural candidate to describe such dynamics. Unparticle stuff is scale-invariant matter with no particular mass. Scale invariance dictates that the propagator has an algebraic form which can admit zeros and hence is a candidate to explain the ubiquitous pseudogap state of the cuprates. The non-perturbative electronic state formed out of unparticles we refer to as an un-Fermi liquid. We show that the underlying action of the continuous mass formulation of unparticles can be recast as an action in anti de Sitter space which serves as the generating functional for the propagator. We find that this mapping fixes the scaling dimension of the unparticle to be dU = d / 2 +√{d2 + 4 } / 2 and ensures that the corresponding propagator has zeros with d the spacetime dimension of the unparticle field. This work was funded by NSF DMR-1104909, DMR-1005536 and DMR-0820404.

  1. Quasiparticles of strongly correlated Fermi liquids at high temperatures and in high magnetic fields

    SciTech Connect

    Shaginyan, V. R.

    2011-08-15

    Strongly correlated Fermi systems are among the most intriguing, best experimentally studied and fundamental systems in physics. There is, however, lack of theoretical understanding in this field of physics. The ideas based on the concepts like Kondo lattice and involving quantum and thermal fluctuations at a quantum critical point have been used to explain the unusual physics. Alas, being suggested to describe one property, these approaches fail to explain the others. This means a real crisis in theory suggesting that there is a hidden fundamental law of nature. It turns out that the hidden fundamental law is well forgotten old one directly related to the Landau-Migdal quasiparticles, while the basic properties and the scaling behavior of the strongly correlated systems can be described within the framework of the fermion condensation quantum phase transition (FCQPT). The phase transition comprises the extended quasiparticle paradigm that allows us to explain the non-Fermi liquid (NFL) behavior observed in these systems. In contrast to the Landau paradigm stating that the quasiparticle effective mass is a constant, the effective mass of new quasiparticles strongly depends on temperature, magnetic field, pressure, and other parameters. Our observations are in good agreement with experimental facts and show that FCQPT is responsible for the observed NFL behavior and quasiparticles survive both high temperatures and high magnetic fields.

  2. Quasiparticles of strongly correlated Fermi liquids at high temperatures and in high magnetic fields

    NASA Astrophysics Data System (ADS)

    Shaginyan, V. R.

    2011-08-01

    Strongly correlated Fermi systems are among the most intriguing, best experimentally studied and fundamental systems in physics. There is, however, lack of theoretical understanding in this field of physics. The ideas based on the concepts like Kondo lattice and involving quantum and thermal fluctuations at a quantum critical point have been used to explain the unusual physics. Alas, being suggested to describe one property, these approaches fail to explain the others. This means a real crisis in theory suggesting that there is a hidden fundamental law of nature. It turns out that the hidden fundamental law is well forgotten old one directly related to the Landau-Migdal quasiparticles, while the basic properties and the scaling behavior of the strongly correlated systems can be described within the framework of the fermion condensation quantum phase transition (FCQPT). The phase transition comprises the extended quasiparticle paradigm that allows us to explain the non-Fermi liquid (NFL) behavior observed in these systems. In contrast to the Landau paradigm stating that the quasiparticle effective mass is a constant, the effective mass of new quasiparticles strongly depends on temperature, magnetic field, pressure, and other parameters. Our observations are in good agreement with experimental facts and show that FCQPT is responsible for the observed NFL behavior and quasiparticles survive both high temperatures and high magnetic fields.

  3. Non-Fermi-liquid magic angle effects in high magnetic fields

    NASA Astrophysics Data System (ADS)

    Lebed, A. G.

    2016-07-01

    We investigate a theoretical problem of electron-electron interactions in an inclined magnetic field in a quasi-one-dimensional (Q1D) conductor. We show that they result in strong non-Fermi-liquid corrections to a specific heat, provided that the direction of the magnetic field is far from the so-called Lebed's magic angles (LMAs). If magnetic field is directed close to one of the LMAs, the specific heat corrections become small and the Fermi-liquid picture restores. As a result, we predict Fermi-liquid-non-Fermi-liquid angular crossovers in the vicinities of the LMA directions of the field. We suggest to perform the corresponding experiment in the Q1D conductor (Per) 2Au (mnt) 2 under pressure in magnetic fields of the order of H ≃25 T .

  4. Doniach Phase Diagram, Revisited: From Ferromagnet to Fermi Liquid in Pressurized CeRu{sub 2} Ge{sub 2}

    SciTech Connect

    Suellow, S.; Aronson, M.C.; Rainford, B.D.; Haen, P.

    1999-04-01

    We present the resistivity and ac susceptibility of CeRu{sub 2}Ge {sub 2} at pressures p up to 130thinspthinspkbar. Pressure transforms the system from a ferromagnet into a nonordering Fermi liquid (FL). The suppression of magnetic order at p{sub c}=67 kbar is accompanied by non-Fermi liquid (NFL) behavior. By comparing our results to isoelectronic CeRu{sub 2}( Ge{sub 1{minus}x}Si {sub x}){sub 2} we derive a unified hybridization J phase diagram for the entire material class. The phase diagram is characterized by the FL and Kondo energy scales T{sub FL} and T{sub K} , with the NFL behavior appearing at T{sub FL}=0 K , while T{sub K} remains finite and a smoothly increasing function of J . {copyright} {ital 1999} {ital The American Physical Society}

  5. Doniach Phase Diagram, Revisited: From Ferromagnet to Fermi Liquid in Pressurized CeRu[sub 2] Ge[sub 2

    SciTech Connect

    Suellow, S.; Aronson, M.C. ); Rainford, B.D. ); Haen, P. )

    1999-04-01

    We present the resistivity and ac susceptibility of CeRu[sub 2]Ge [sub 2] at pressures p up to 130thinspthinspkbar. Pressure transforms the system from a ferromagnet into a nonordering Fermi liquid (FL). The suppression of magnetic order at p[sub c]=67 kbar is accompanied by non-Fermi liquid (NFL) behavior. By comparing our results to isoelectronic CeRu[sub 2]( Ge[sub 1[minus]x]Si [sub x])[sub 2] we derive a unified hybridization J phase diagram for the entire material class. The phase diagram is characterized by the FL and Kondo energy scales T[sub FL] and T[sub K] , with the NFL behavior appearing at T[sub FL]=0 K , while T[sub K] remains finite and a smoothly increasing function of J . [copyright] [ital 1999] [ital The American Physical Society

  6. Hidden Fermi liquid: Self-consistent theory for the normal state of high-Tc superconductors

    NASA Astrophysics Data System (ADS)

    Casey, Philip A.

    The anomalous "strange metal" properties of the normal, non-superconducting state of the high-Tc cuprate superconductors have been extensively studied for over two decades. The resistivity is robustly T-linear at high temperatures, while at low T it appears to maintain linearity near optimal doping and is T2 at higher doping. The inverse Hall angle is strictly T2 and hence has a distinct scattering lifetime from the resistivity. The transport scattering lifetime is highly anisotropic as directly measured by angle-dependent magnetoresistance (ADMR) and indirectly in more traditional transport experiments. The IR conductivity exhibits a non-integer power-law in frequency, which we take as a defining characteristic of the "strange metal". A phenomenological theory of the transport and spectroscopic properties at a self-consistent and predictive level has been much sought after, yet elusive. Hidden Fermi liquid theory (HFL) explicitly accounts for the effects of Gutzwiller projection in the t-J Hamiltonian, widely believed to contain the essential physics of the high-Tc superconductors. We show this theory to be the first self-consistent description for the normal state of the cuprates based on transparent, fundamental assumptions. Our well-defined formalism also serves as a guide for further experimental confirmation. Chapter 1 reviews the "strange metal" properties and the relevant aspects of competing models. Chapter 2 presents the theoretical foundations of the formalism. Chapters 3 and 4 derive expressions for the entire normal state relating many of the properties, for example: angle-resolved photoemission, IR conductivity, resistivity, Hall angle, and by generalizing the formalism to include the Fermi surface topology---ADMR. Self-consistency is demonstrated with experimental comparisons, including the most recent laser-ARPES and ADMR. Chapter 5 discusses entropy transport, as in the thermal conductivity, thermal Hall conductivity, and consequent metrics of non-Fermi

  7. Extremely correlated Fermi liquids in the limit of infinite dimensions

    SciTech Connect

    Perepelitsky, Edward Sriram Shastry, B.

    2013-11-15

    We study the infinite spatial dimensionality limit (d→∞) of the recently developed Extremely Correlated Fermi Liquid (ECFL) theory (Shastry 2011, 2013) [17,18] for the t–J model at J=0. We directly analyze the Schwinger equations of motion for the Gutzwiller projected (i.e. U=∞) electron Green’s function G. From simplifications arising in this limit d→∞, we are able to make several exact statements about the theory. The ECFL Green’s function is shown to have a momentum independent Dyson (Mori) self energy. For practical calculations we introduce a partial projection parameter λ, and obtain the complete set of ECFL integral equations to O(λ{sup 2}). In a related publication (Zitko et al. 2013) [23], these equations are compared in detail with the dynamical mean field theory for the large U Hubbard model. Paralleling the well known mapping for the Hubbard model, we find that the infinite dimensional t–J model (with J=0) can be mapped to the infinite-U Anderson impurity model with a self-consistently determined set of parameters. This mapping extends individually to the auxiliary Green’s function g and the caparison factor μ. Additionally, the optical conductivity is shown to be obtainable from G with negligibly small vertex corrections. These results are shown to hold to each order in λ. -- Highlights: •Infinite-dimensional t–J model (J=0) studied within new ECFL theory. •Mapping to the infinite U Anderson model with self consistent hybridization. •Single particle Green’s function determined by two local self energies. •Partial projection through control variable λ. •Expansion carried out to O(λ{sup 2}) explicitly.

  8. Protection of a non-Fermi liquid by spin-orbit interaction

    NASA Astrophysics Data System (ADS)

    Nguyen, T. K. T.; Kiselev, M. N.

    2015-07-01

    We show that a thermoelectric transport through a quantum dot-single-mode quantum point contact nanodevice demonstrating pronounced fingerprints of nonFermi liquid (NFL) behavior in the absence of external magnetic field is protected from magnetic field NFL destruction by strong spin-orbit interaction (SOI). The mechanism of protection is associated with the appearance of additional scattering processes due to lack of spin conservation in the presence of both SOI and small Zeeman field. The interplay between in-plane magnetic field B ⃗ and SOI is controlled by the angle between B ⃗ and B⃗SOI. We predict strong dependence of the thermoelectric coefficients on the orientation of the magnetic field and discuss a window of parameters for experimental observation of NFL effects.

  9. Analytic Flow Equations for the Fermi Liquid Parameters of the Anderson Impurity Model.

    PubMed

    Pandis, Vassilis; Hewson, Alex C

    2015-08-14

    The low temperature behavior of a Fermi liquid can be described in terms of quasiparticle excitations that are in 1-1 correspondence with those of the noninteracting system. Because of adiabatic continuity, the Landau parameters, which describe the interactions between the quasiparticles, must evolve continuously as the interactions are turned on and be described by a set of flow equations. For strongly correlated electron systems it is not possible to follow this flow in perturbation theory when the interactions become strong. We explore the idea here of overcoming this problem by renormalizing the quasiparticles in this flow using a renormalized perturbation theory. This approach is tested in the case of a single impurity Anderson model. Analytic flow equations are derived which give excellent results for the Landau parameters in the strong correlation regime.

  10. Non-Fermi-liquid nature and exotic thermoelectric power in the heavy-fermion superconductor UBe13

    NASA Astrophysics Data System (ADS)

    Shimizu, Yusei; Pourret, Alexandre; Knebel, Georg; Palacio-Morales, Alexandra; Aoki, Dai

    2015-12-01

    We report quite exotic thermoelectric power S in UBe13. At 0 T, the negative S /T continues to strongly enhance down to the superconducting transition temperature with no Fermi-liquid behavior. |S /T | is dramatically suppressed and becomes rather modest with increasing field. We have also obtained precise field dependencies of (i) an anomaly in S due to an exotic Kondo effect and (ii) a field-induced anomaly in S /T associated with the anomalous upward Hc 2(T ) . In contrast to the field-sensitive transport property, the normal-state specific heat is magnetically robust, indicating that the largeness of the 5 f density of states remains in high fields. This unusual behavior in UBe13 can be explained by a considerable change in the energy derivative of the conduction-electron lifetime τc(ɛ ) at the Fermi level under magnetic fields.

  11. Non-Fermi liquid phase and non-Gaussian itinerant quantum criticality of Weyl semimetals

    NASA Astrophysics Data System (ADS)

    Goswami, Pallab

    A Weyl semimetal is a gapless topological phase in three dimensions, for which the touching points between two nondegenerate bands act as monopoles and antimonopoles of Abelian Berry curvature, with monopole strength m. Such a gapless phase can support m Fermi arcs as the protected, zero energy surface states. We consider the stability of a generalized Weyl semimetal with m > 1 in the presence of interaction and disorder by employing a renormalization group analysis, which is controlled by the parameter ɛ = 1 -1/m . For any m > 1 , we show how the long range Coulomb interaction gives rise to an infra-red stable, non-Fermi liquid phase without any sharp quasiparticle pole. In the presence of sufficiently strong short range interactions, the non-Fermi liquid can transform into a translational symmetry breaking, axionic insulator. We demonstrate that the associated itinerant quantum critical point possesses non-Gaussian scaling properties. We establish the stability of the emergent non-Fermi liquid phase and the itinerant quantum critical point against weak disorder. Finally, we discuss the scaling properties of physical quantities, the fate of the Fermi arcs, and the experimental relevance of our results for some candidate materials. NSF.

  12. Fractionalized Fermi liquid on the surface of a topological Kondo insulator

    NASA Astrophysics Data System (ADS)

    Thomson, Alex; Sachdev, Subir

    2016-03-01

    We argue that topological Kondo insulators can also have "intrinsic" topological order associated with fractionalized excitations on their surfaces. The hybridization between the local moments and conduction electrons can weaken near the surface, and this enables the local moments to form spin liquids. This coexists with the conduction electron surface states, realizing a surface fractionalized Fermi liquid. We present mean-field solutions of a Kondo-Heisenberg model in two spatial dimensions which display such surfaces.

  13. Non Fermi liquid ground states in strongly correlated f-electron materials

    SciTech Connect

    Maple, M.B.; Andrade, M.C. de; Herrmann, J.

    1995-05-01

    Experimental efforts to characterize and develop an understanding of non Fermi liquid (NFL) behavior at low temperature in f-electron materials are reviewed for three f-electron systems: M{sub 1-x}U{sub x}Pd{sub 3} (M = Sc, Y), U{sub 1-x}Th{sub x}Pd{sub 2}Al{sub 3}, and UCu{sub 5-x}Pd{sub x}. The emerging systematics of NFL behavior in f-electron systems, based on the present sample of nearly ten f-electron systems, is updated. Many of the f-electron systems exhibit the following temperature dependences of the electrical resistivity {rho}, specific heat C, and magnetic susceptibility x for T {much_lt} T{sub 0}, where T{sub 0} is a characteristic temperature: {rho}(T) {approximately} 1 - aT/T{sub 0}, where a < 0 or > 0, C(T)/T {approximately} (-1/T{sub 0})ln(T/bT{sub 0}), and x(T) {approximately} 1 - c(T/T{sub 0}){sup 1/2}. In several of the f-electron systems, the characteristic temperature T{sub 0} can be identified with the Kondo temperature T{sub K}.

  14. Strong Quantum Coherence between Fermi Liquid Mahan Excitons.

    PubMed

    Paul, J; Stevens, C E; Liu, C; Dey, P; McIntyre, C; Turkowski, V; Reno, J L; Hilton, D J; Karaiskaj, D

    2016-04-15

    In modulation doped quantum wells, the excitons are formed as a result of the interactions of the charged holes with the electrons at the Fermi edge in the conduction band, leading to the so-called "Mahan excitons." The binding energy of Mahan excitons is expected to be greatly reduced and any quantum coherence destroyed as a result of the screening and electron-electron interactions. Surprisingly, we observe strong quantum coherence between the heavy hole and light hole excitons. Such correlations are revealed by the dominating cross-diagonal peaks in both one-quantum and two-quantum two-dimensional Fourier transform spectra. Theoretical simulations based on the optical Bloch equations where many-body effects are included phenomenologically reproduce well the experimental spectra. Time-dependent density functional theory calculations provide insight into the underlying physics and attribute the observed strong quantum coherence to a significantly reduced screening length and collective excitations of the many-electron system.

  15. Non-Fermi-Liquid Single Particle Line Shape of the Quasi-One-Dimensional Non-CDW Metal Li{sub 0.9}Mo{sub 6}O{sub 17} : Comparison to the Luttinger Liquid

    SciTech Connect

    Denlinger, J.D.; Gweon, G.; Allen, J.W.; Schlenker, C.; Hsu, L.; Olson, C.G.; Marcus, J.

    1999-03-01

    We report the detailed non-Fermi-liquid (NFL) line shape of the dispersing excitation which defines the Fermi surface for quasi-one-dimensional Li{sub 0.9}Mo {sub 6}O{sub 17} . The properties of Li{sub 0.9}Mo {sub 6}O{sub 17} strongly suggest that the NFL behavior has a purely electronic origin. In relation to the theoretical Luttinger liquid line shape, we identify significant similarities, but also important differences. {copyright} {ital 1999} {ital The American Physical Society}

  16. Spin Relaxation in Hyperpolarized He-3 Fermi Liquids

    NASA Astrophysics Data System (ADS)

    Stanton, Liam; Bedell, Kevin

    2004-03-01

    In the past few years, attention has been drawn towards the hyperpolarized gases of Xenon-129 and Helium-3 isotopes. Medical research has explored the possibilities of using these isotopes for magnetic resonance imaging (MRI) of the lungs in both human and animal test subjects. Because the atoms of hyperpolarized gas are forced into a specific spin state, the MRI signal is enhanced. While the spin relaxation times of Helium-3 can be calculated in the high and low temperature limits, there exists no exact analytic solution for intermediate temperatures. The intention of this research was to numerically connect these limits with an accurate approximation. To do this, various analytic and numerical methods were used to reduce the spin relaxation time to a function of temperature, chemical potential, and particle number. Additional numerical methods were then used to calculate the chemical potential of Helium-3. The data show that a minimum occurs in the spin relaxation time at the order of the Fermi temperature, after which the classical limit is rapidly approached. These computational results seem to coincide with those expected.

  17. Strong quantum coherence between Fermi liquid Mahan excitons

    DOE PAGES

    Paul, J.; Stevens, C. E.; Liu, C.; Dey, P.; McIntyre, C.; Turkowski, V.; Reno, J. L.; Hilton, D. J.; Karaiskaj, D.

    2016-04-14

    In modulation doped quantum wells, the excitons are formed as a result of the interactions of the charged holes with the electrons at the Fermi edge in the conduction band, leading to the so-called “Mahan excitons.” The binding energy of Mahan excitons is expected to be greatly reduced and any quantum coherence destroyed as a result of the screening and electron-electron interactions. Surprisingly, we observe strong quantum coherence between the heavy hole and light hole excitons. Such correlations are revealed by the dominating cross-diagonal peaks in both one-quantum and two-quantum two-dimensional Fourier transform spectra. Theoretical simulations based on the opticalmore » Bloch equations where many-body effects are included phenomenologically reproduce well the experimental spectra. Furthermore, time-dependent density functional theory calculations provide insight into the underlying physics and attribute the observed strong quantum coherence to a significantly reduced screening length and collective excitations of the many-electron system.« less

  18. Strong Quantum Coherence between Fermi Liquid Mahan Excitons.

    PubMed

    Paul, J; Stevens, C E; Liu, C; Dey, P; McIntyre, C; Turkowski, V; Reno, J L; Hilton, D J; Karaiskaj, D

    2016-04-15

    In modulation doped quantum wells, the excitons are formed as a result of the interactions of the charged holes with the electrons at the Fermi edge in the conduction band, leading to the so-called "Mahan excitons." The binding energy of Mahan excitons is expected to be greatly reduced and any quantum coherence destroyed as a result of the screening and electron-electron interactions. Surprisingly, we observe strong quantum coherence between the heavy hole and light hole excitons. Such correlations are revealed by the dominating cross-diagonal peaks in both one-quantum and two-quantum two-dimensional Fourier transform spectra. Theoretical simulations based on the optical Bloch equations where many-body effects are included phenomenologically reproduce well the experimental spectra. Time-dependent density functional theory calculations provide insight into the underlying physics and attribute the observed strong quantum coherence to a significantly reduced screening length and collective excitations of the many-electron system. PMID:27127985

  19. Non-Fermi-liquid scaling in U(Cu,Al){sub 5} compounds

    SciTech Connect

    Nakotte, H.; Buschow, K.H.J.; Brueck, E.; Klaasse, J.C.P.

    1996-08-01

    We report on the electronic properties of various UCu{sub x}Al{sub 5-x} compounds (2.9{le}x{le}3.5). These compounds crystallize in the hexagonal CaCu{sub 5} structure. For all compounds, we find that the low-temperature specific heat diverges logarithmitically, which may be taken as an indication of non-Fermi-liquid scaling in these materials. Also we find a large magnetic anisotropy in all compounds studied, and we show that the magnetic anisotropy should not be neglected in the analysis of other bulk properties. Though for some of UCu{sub x}Al{sub 5-x} polycrystals non-Fermi-liquid scaling is found also in the magnetic susceptibility, comparison with single-crystal results on UCu{sub 3}Al{sub 2} indicates that any temperature dependence may be due to averaging anisotropic response over all crystallographic directions.

  20. Reprint of : Regular and singular Fermi liquid in triple quantum dots: Coherent transport studies

    NASA Astrophysics Data System (ADS)

    Tooski, S. B.; Ramšak, A.; Bułka, B. R.

    2016-08-01

    A system of three coupled quantum dots in a triangular geometry (TQD) with electron-electron interaction and symmetrically coupled to two leads is analyzed with respect to the electron transport by means of the numerical renormalization group. Varying gate potentials this system exhibits extremely rich range of regimes with different many-electron states with various local spin orderings. It is demonstrated how the Luttinger phase changes in a controlled manner which then via the Friedel sum rule formula exactly reproduces the conductance through the TQD system. The analysis of the uncoupled TQD molecule from the leads gives a reliable qualitative understanding of various relevant regimes and an insight into the phase diagram with the regular Fermi liquid and singular-Fermi liquid phases.

  1. Direct observation of a Fermi liquid-like normal state in an iron-pnictide superconductor.

    PubMed

    Tytarenko, Alona; Huang, Yingkai; de Visser, Anne; Johnston, Steve; van Heumen, Erik

    2015-01-01

    There are two prerequisites for understanding high-temperature (high-Tc) superconductivity: identifying the pairing interaction and obtaining a correct description of the normal state from which superconductivity emerges. The nature of the normal state of iron-pnictide superconductors, and the role played by correlations arising from partially screened interactions, are still under debate. Here we show that the normal state of carefully annealed electron-doped BaFe(2-x)Co(x)As2 at low temperatures has all the hallmark properties of a local Fermi liquid, with a more incoherent state emerging at elevated temperatures, an identification made possible using bulk-sensitive optical spectroscopy with high frequency and temperature resolution. The frequency dependent scattering rate extracted from the optical conductivity deviates from the expected scaling M2 (ω, T) ∝ (ħω)(2) + (pπkBT)(2) with p ≈ 1.47 rather than p = 2, indicative of the presence of residual elastic resonant scattering. Excellent agreement between the experimental results and theoretical modeling allows us to extract the characteristic Fermi liquid scale T0 ≈ 1700 K. Our results show that the electron-doped iron-pnictides should be regarded as weakly correlated Fermi liquids with a weak mass enhancement resulting from residual electron-electron scattering from thermally excited quasi-particles. PMID:26201499

  2. Fermi-liquid breakdown in the paramagnetic phase of a pure metal.

    PubMed

    Doiron-Leyraud, N; Walker, I R; Taillefer, L; Steiner, M J; Julian, S R; Lonzarich, G G

    2003-10-01

    Fermi-liquid theory (the standard model of metals) has been challenged by the discovery of anomalous properties in an increasingly large number of metals. The anomalies often occur near a quantum critical point--a continuous phase transition in the limit of absolute zero, typically between magnetically ordered and paramagnetic phases. Although not understood in detail, unusual behaviour in the vicinity of such quantum critical points was anticipated nearly three decades ago by theories going beyond the standard model. Here we report electrical resistivity measurements of the 3d metal MnSi, indicating an unexpected breakdown of the Fermi-liquid model--not in a narrow crossover region close to a quantum critical point where it is normally expected to fail, but over a wide region of the phase diagram near a first-order magnetic transition. In this regime, corrections to the Fermi-liquid model are expected to be small. The range in pressure, temperature and applied magnetic field over which we observe an anomalous temperature dependence of the electrical resistivity in MnSi is not consistent with the crossover behaviour widely seen in quantum critical systems. This may suggest the emergence of a well defined but enigmatic quantum phase of matter.

  3. Unconventional non-Fermi liquid state caused by nematic criticality in cuprates

    NASA Astrophysics Data System (ADS)

    Wang, Jing-Rong; Liu, Guo-Zhu; Zhang, Chang-Jin

    2016-07-01

    At the nematic quantum critical point that exists in the {d}{x2-{y}2}-wave superconducting dome of cuprates, the massless nodal fermions interact strongly with the quantum critical fluctuation of nematic order. We study this problem by means of the renormalization group approach and show that, the fermion damping rate | {Im}{{{Σ }}}R(ω )| vanishes more rapidly than the energy ω and the quasiparticle residue {Z}f\\to 0 in the limit ω \\to 0. The nodal fermions thus constitute an unconventional non-Fermi liquid that represents an even weaker violation of Fermi liquid theory than a marginal Fermi liquid. We also investigate the interplay of quantum nematic critical fluctuation and gauge-potential-like disorder, and find that the effective disorder strength flows to the strong coupling regime at low energies. Therefore, even an arbitrarily weak disorder can drive the system to become a disorder controlled diffusive state. Based on these theoretical results, we are able to understand a number of interesting experimental facts observed in curpate superconductors.

  4. Transport phenomena in correlated quantum liquids: Ultracold Fermi gases and F/N junctions

    NASA Astrophysics Data System (ADS)

    Li, Hua

    Landau Fermi-liquid theory was first introduced by L. D. Landau in the effort of understanding the normal state of Fermi systems, where the application of the concept of elementary excitations to the Fermi systems has proved very fruitful in clarifying the physics of strongly correlated quantum systems at low temperatures. In this thesis, I use Landau Fermi-liquid theory to study the transport phenomena of two different correlated quantum liquids: the strongly interacting ultracold Fermi gases and the ferromagnet/normal-metal (F/N) junctions. The detailed work is presented in chapter II and chapter III of this thesis, respectively. Chapter I holds the introductory part and the background knowledge of this thesis. In chapter II, I study the transport properties of a Fermi gas with strong attractive interactions close to the unitary limit. In particular, I compute the transport lifetimes of the Fermi gas due to superfluid fluctuations above the BCS transition temperature Tc. To calculate the transport lifetimes I need the scattering amplitudes. The scattering amplitudes are dominated by the superfluid fluctuations at temperatures just above Tc. The normal scattering amplitudes are calculated from the Landau parameters. These Landau parameters are obtained from the local version of the induced interaction model for computing Landau parameters. I also calculate the leading order finite temperature corrections to the various transport lifetimes. A calculation of the spin diffusion coefficient is presented in comparison to the experimental findings. Upon choosing a proper value of F0a, I am able to present a good match between the theoretical result and the experimental measurement, which indicates the presence of the superfluid fluctuations near Tc. Calculations of the viscosity, the viscosity/entropy ratio and the thermal conductivity are also shown in support of the appearance of the superfluid fluctuations. In chapter III, I study the spin transport in the low

  5. Nonlinear optical conductivity of U (1 ) spin liquids with large spinon Fermi surfaces

    NASA Astrophysics Data System (ADS)

    Ma, Yuan-Fei; Ng, Tai-Kai

    2016-06-01

    In this paper we study the nonlinear current response of U (1 ) spin liquids with large spinon Fermi surfaces under the perturbation of a time-dependent ac electric field E (t ) within the framework of an effective U (1 ) gauge theory. In particular, the third-order nonlinear current response to ac electric fields is derived. We show that as in the case of linear current response, an in-gap power-law (˜ωη ) response is found for the nonlinear current at low frequency. The nonlinear susceptibility may also induce through process of third harmonic generation propagating EM wave with frequency 3 ω inside the spin liquids.

  6. Heat diffusion in the disordered Fermi and electron liquids: the role of inelastic processes

    NASA Astrophysics Data System (ADS)

    Schwiete, Georg; Finkel'Stein, Alexander

    2015-03-01

    We study thermal transport in the disordered Fermi and electron liquids at low temperatures. Gravitational potentials are used as sources for finding the heat density and its correlation function. For a comprehensive study, we extend the renormalization group (RG) analysis developed for electric transport by including the gravitational potentials into the RG scheme. The analysis reveals that for the disordered Fermi liquid the Wiedemann-Franz law remains valid even in the presence of quantum corrections caused by the interplay of diffusion modes and the electron-electron interaction. In the present scheme this fundamental relation is closely connected with a fixed point in the multi-parametric RG flow of the gravitational potentials. For the disordered electron liquid we additionally analyze inelastic processes induced by the Coulomb interaction at sub-temperature energies. While the general form of the correlation function has to be compatible with energy conservation, these inelastic processes are at the origin of logarithmic corrections violating the Wiedemann-Franz law. The interplay of various terms in the heat density-heat density correlation function therefore differs from that for densities of other conserved quantities, such as total number of particles or spin. A. F. and G. S. acknowledge support by the Alexander von Humboldt foundation. A.F. is supported by the National Science Foundation Grant NSF-DMR-1006752.

  7. Ultrashort Optical Pulses in a Fermi Liquid and Duality of Gauge Gravitation

    NASA Astrophysics Data System (ADS)

    Konobeeva, N. N.; Belonenko, M. B.

    2016-07-01

    The problem of the propagation of ultrashort pulses, including both two-dimensional and three-dimensional pulses, in a Fermi liquid is considered with the help of representations of the duality of gauge gravitation. The electromagnetic field is considered classically on the basis of the Maxwell equations. The effective equation so obtained is analyzed numerically and the dynamics of the state of the electromagnetic field are elucidated in the planar case, and also when it is localized in two/three spatial dimensions.

  8. Composite-fermion theory for pseudogap, Fermi arc, hole pocket, and non-Fermi liquid of underdoped cuprate superconductors.

    PubMed

    Yamaji, Youhei; Imada, Masatoshi

    2011-01-01

    We propose that an extension of the exciton concept to doped Mott insulators offers a fruitful insight into challenging issues of the copper oxide superconductors. In our extension, new fermionic excitations called cofermions emerge in conjunction to generalized excitons. The cofermions hybridize with conventional quasiparticles. Then a hybridization gap opens, and is identified as the pseudogap observed in the underdoped cuprates. The resultant Fermi-surface reconstruction naturally explains a number of unusual properties of the underdoped cuprates, such as the Fermi arc and/or pocket formation.

  9. Entanglement entropy of composite Fermi liquid states on the lattice: In support of the Widom formula

    NASA Astrophysics Data System (ADS)

    Mishmash, Ryan V.; Motrunich, Olexei I.

    2016-08-01

    Quantum phases characterized by surfaces of gapless excitations are known to violate the otherwise ubiquitous boundary law of entanglement entropy in the form of a multiplicative log correction: S ˜Ld -1logL . Using variational Monte Carlo, we calculate the second Rényi entropy for a model wave function of the ν =1 /2 composite Fermi liquid (CFL) state defined on the two-dimensional triangular lattice. By carefully studying the scaling of the total Rényi entropy and, crucially, its contributions from the modulus and sign of the wave function on various finite-size geometries, we argue that the prefactor of the leading L logL term is equivalent to that in the analogous free fermion wave function. In contrast to the recent results of Shao et al. [Phys. Rev. Lett. 114, 206402 (2015), 10.1103/PhysRevLett.114.206402], we thus conclude that the "Widom formula" holds even in this non-Fermi liquid CFL state. More generally, our results further elucidate—and place on a more quantitative footing—the relationship between nontrivial wave function sign structure and S ˜L logL entanglement scaling in such highly entangled gapless phases.

  10. Many-body local fields and Fermi-liquid parameters in a quasi-two-dimensional electron liquid

    NASA Astrophysics Data System (ADS)

    Yarlagadda, Sudhakar; Giuliani, Gabriele F.

    1994-05-01

    We present a quantitative theory of the quasiparticle properties in a Fermi liquid. Our approach uses as an input our previous result for the quasiparticle energy which incorporates the vertex corrections associated with charge and spin-density fluctuations through suitably defined many-body local fields. The method is explicitly applied to the case of the quasi-two-dimensional electron liquid occurring in silicon inversion layers. In particular, we discuss results for the effective mass m* and the modified Landé factor g* (Wilson ratio) that are in reasonable agreement with reported findings. Our calculations are performed by making use of a self-consistent static model for the many-body local fields and are consequently free of arbitrary parameters.

  11. Phase diagram and Fermi liquid properties of the extended Hubbard model on the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Tremblay, A.-M. S.

    2014-05-01

    The Hubbard and extended Hubbard models on the honeycomb lattice can be seen as prototype models of a single-layer graphene placed in a high dielectric constant environment that screens the Coulomb interaction. Taking advantage of the absence of a sign problem at half-filling, we study this problem with clusters up to 96 sites with the determinant quantum Monte Carlo method as an impurity solver for the dynamical cluster approximation at finite temperatures. After determining the stability of the semimetallic phase to interaction-induced spin-density wave (SDW), charge-density wave (CDW), and Mott insulating phases, we study the single-particle dynamics of the Dirac fermions. We show that when spontaneous symmetry breaking is avoided, the semimetallic phase is a stable Fermi liquid in the presence of repulsive interactions and that Kondo screening dominates the low temperature regime, even though there is a ρ (ω)=|ω| type local density of states. We also investigate the impact of the correlation effects on the renormalization of the Fermi velocity vF. We find that vF is not renormalized when only on-site repulsion U is present, but that near-neighbor repulsion V does renormalize vF. This may explain the variations between different measurements of vF in graphene.

  12. Field-Enhanced Kondo Correlations in a Half-Filling Nanotube Dot: Evolution of an SU(N) Fermi-Liquid Fixed Point

    NASA Astrophysics Data System (ADS)

    Teratani, Yoshimichi; Sakano, Rui; Fujiwara, Ryo; Hata, Tokuro; Arakawa, Tomonori; Ferrier, Meydi; Kobayashi, Kensuke; Oguri, Akira

    2016-09-01

    Carbon nanotube quantum dot has four-fold degenerate one-particle levels, which bring a variety to the Kondo effects taking place in a wide tunable-parameter space. We theoretically study an emergent SU(2) symmetry that is suggested by recent magneto-transport measurements, carried out near two electrons filling. It does not couple with the magnetic field, and emerges in the case where the spin and orbital Zeeman splittings cancel each other out in two of the one-particle levels among four. This situation seems to be realized in the recent experiment. Using the Wilson numerical renormalization group, we show that a crossover from the SU(4) to SU(2) Fermi-liquid behavior occurs as magnetic field increases at two impurity-electrons filling. We also find that the quasiparticles are significantly renormalized as the remaining two one-particle levels move away from the Fermi level and are frozen at high magnetic fields. Furthermore, we consider how the singlet ground state evolves during such a crossover. Specifically, we reexamine the SU(N) Kondo singlet for M impurity-electrons filling in the limit of strong exchange interactions. We find that the nondegenerate Fermi-liquid fixed point of Nozières and Blandin can be described as abosonic Perron-Frobenius vector for M composite pairs, each of which consists of one impurity-electron and one conduction-hole. This interpretation in terms of the Perron-Frobenius theorem can also be extended to the Fermi-liquid fixed-point without the SU(N) symmetry.

  13. Non-Fermi liquid correction to the neutrino mean free path and emissivity in neutron star beyond the leading order

    NASA Astrophysics Data System (ADS)

    Adhya, Souvik P.; Roy, P. K.; Dutt-Mazumder, Abhee K.

    2013-04-01

    In this work we have derived the expressions of the mean free path (MFP) and emissivity of the neutrinos by incorporating non-Fermi liquid (NFL) corrections upto next to leading order (NLO). We have shown how such corrections affect the cooling of the neutron star composed of quark matter core.

  14. Nematic quantum phase transition of composite Fermi liquids in half-filled Landau levels and their geometric response

    NASA Astrophysics Data System (ADS)

    You, Yizhi; Cho, Gil Young; Fradkin, Eduardo

    2016-05-01

    We present a theory of the isotropic-nematic quantum phase transition in the composite Fermi liquid arising in half-filled Landau levels. We show that the quantum phase transition between the isotropic and the nematic phase is triggered by an attractive quadrupolar interaction between electrons, as in the case of conventional Fermi liquids. We derive the theory of the nematic state and of the phase transition. This theory is based on the flux attachment procedure, which maps an electron liquid in half-filled Landau levels into the composite Fermi liquid close to a nematic transition. We show that the local fluctuations of the nematic order parameters act as an effective dynamical metric interplaying with the underlying Chern-Simons gauge fields associated with the flux attachment. Both the fluctuations of the Chern-Simons gauge field and the nematic order parameter can destroy the composite fermion quasiparticles and drive the system into a non-Fermi liquid state. The effective-field theory for the isotropic-nematic phase transition is shown to have z =3 dynamical exponent due to the Landau damping of the dense Fermi system. We show that there is a Berry-phase-type term that governs the effective dynamics of the nematic order parameter fluctuations, which can be interpreted as a nonuniversal "Hall viscosity" of the dynamical metric. We also show that the effective-field theory of this compressible fluid has a Wen-Zee-type term. Both terms originate from the time-reversal breaking fluctuation of the Chern-Simons gauge fields. We present a perturbative (one-loop) computation of the Hall viscosity and also show that this term is also obtained by a Ward identity. We show that the topological excitation of the nematic fluid, the disclination, carries an electric charge. We show that a resonance observed in radio-frequency conductivity experiments can be interpreted as a Goldstone nematic mode gapped by lattice effects.

  15. Nematic quantum phase transition of composite Fermi liquids in half-filled Landau levels and their geometric response

    NASA Astrophysics Data System (ADS)

    You, Yizhi; Cho, Gil Young; Fradkin, Eduardo

    We present a theory of isotropic-nematic quantum phase transition in the composite Fermi liquid arising in the half-filled Landau levels. We show that the quantum phase transition is triggered by the attractive quadrupolar interaction. By performing flux attachment, system turns into a composite Fermi liquid. The nematic order parameters act as the dynamical metric interplaying with the underlying topology, the Chern-Simons theory. Here both the fluctuations of the gauge field and the nematic order parameter can soften the Fermi surface and thus the fermions form a non-Fermi liquid. The effective field theory for the isotropic-nematic phase transition has z = 3 dynamical exponent due to the Landau damping due to the finite density of the fermions. We show that there is a Berry phase term of the nematic order parameter, which can be interpreted as the ``Hall viscosity'' of the dynamical metric. We also find the Wen-Zee-like term, which effectively dresses the nematic vortex with the electric charge. Both of the terms are originated from the time reversal breaking fluctuation of the Chern-Simons gauge fields. This indicates the fluctuations of the gauge fields modify the Hall viscosity and orbital spin of the compressible half-filled Landau level.

  16. Superconductivity from a confinement transition out of a fractionalized Fermi liquid with Z2 topological and Ising-nematic orders

    NASA Astrophysics Data System (ADS)

    Chatterjee, Shubhayu; Qi, Yang; Sachdev, Subir; Steinberg, Julia

    2016-07-01

    The Schwinger boson theory of the frustrated square lattice antiferromagnet yields a stable, gapped Z2 spin liquid ground state with time-reversal symmetry, incommensurate spin correlations, and long-range Ising-nematic order. We obtain an equivalent description of this state using fermionic spinons (the fermionic spinons can be considered to be bound states of the bosonic spinons and the visons). Upon doping, the Z2 spin liquid can lead to a fractionalized Fermi liquid (FL*) with small Fermi pockets of electronlike quasiparticles, while preserving the Z2 topological and Ising-nematic orders. We describe a Higgs transition out of this deconfined metallic state into a confining superconducting state which is almost always of the Fulde-Ferrell-Larkin-Ovchinnikov type, with spatial modulation of the superconducting order.

  17. Spin-fluctuation induced non-Fermi-liquid behaviour with suppressed superconductivity in LiFe1-xCoxAs

    NASA Astrophysics Data System (ADS)

    Miao, Hu; Dai, Yaomin; Xing, Lingyi; Wang, Xiancheng; Wang, Pengshuai; Xiao, Hong; Qian, Tian; Richard, Pierre; Qiu, Xianggang; Yu, Weiqiang; Jin, Changqing; Wang, Ziqiang; Johnson, P. D.; Homes, C. C.; Ding, Hong

    We study a series of LiFe1-xCoxAs compounds with different Co concentrations by transport, optical spectroscopy, angle-resolved photoemission spectroscopy, and nuclear magnetic resonance. We observe a Fermi-liquid to non-Fermi-liquid to Fermi-liquid (FL-NFL-FL) crossover alongside a monotonic suppression of the superconductivity with increasing Co content. In parallel to the FL-NFL-FL crossover, we find that both the low-energy spin fluctuations and Fermi surface nesting are enhanced and then diminished, strongly suggesting that the NFL behaviour in LiFe1-xCoxAs is induced by low-energy spin fluctuations that are very likely tuned by Fermi surface nesting. Our study reveals a unique phase diagram of LiFe1-xCoxAs where the region of NFL is moved to the boundary of the superconducting phase, implying that they are probably governed by different mechanisms.

  18. A Multiwavelength Study on the High-energy Behavior of the Fermi/LAT Pulsars

    NASA Astrophysics Data System (ADS)

    Marelli, Martino; De Luca, Andrea; Caraveo, Patrizia A.

    2011-06-01

    Using archival as well as freshly acquired data, we assess the X-ray behavior of the Fermi/Large Area Telescope γ-ray pulsars listed in the First Fermi source catalog. After revisiting the relationships between the pulsars' rotational energy losses and their X-ray and γ-ray luminosities, we focus on the distance-independent γ-to-X-ray flux ratios. When plotting our F γ/F X values as a function of the pulsars' rotational energy losses, one immediately sees that pulsars with similar energetics have F γ/F X spanning three decades. Such spread, most probably stemming from vastly different geometrical configurations of the X-ray and γ-ray emitting regions, defies any straightforward interpretation of the plot. Indeed, while energetic pulsars do have low F γ/F X values, little can be said for the bulk of the Fermi neutron stars. Dividing our pulsar sample into radio-loud and radio-quiet subsamples, we find that, on average, radio-quiet pulsars do have higher values of F γ/F X , implying an intrinsic faintness of their X-ray emission and/or a different geometrical configuration. Moreover, despite the large spread mentioned above, statistical tests show a lower scatter in the radio-quiet data set with respect to the radio-loud one, pointing to a somewhat more constrained geometry for the radio-quiet objects with respect to the radio-loud ones.

  19. Quasiparticle interaction function in a two-dimensional Fermi liquid near an antiferromagnetic critical point

    NASA Astrophysics Data System (ADS)

    Chubukov, Andrey V.; Wölfle, Peter

    2014-01-01

    We present the expression for the quasiparticle vertex function Γω(KF,PF) (proportional to the Landau interaction function) in a 2D Fermi liquid (FL) near an instability towards antiferromagnetism. This function is relevant in many ways in the context of metallic quantum criticality. Previous studies have found that near a quantum critical point, the system enters into a regime in which the fermionic self-energy is large near hot spots on the Fermi surface [points on the Fermi surface connected by the antiferromagnetic ordering vector qπ=(π,π)] and has much stronger dependence on frequency than on momentum. We show that in this regime, which we termed a critical FL, the conventional random-phase-approximation- (RPA) type approach breaks down, and to properly calculate the vertex function one has to sum up an infinite series of terms which were explicitly excluded in the conventional treatment. Besides, we show that, to properly describe the spin component of Γω(KF,PF) even in an ordinary FL, one has to add Aslamazov-Larkin (AL) terms to the RPA vertex. We show that the total Γω(KF,PF) is larger in a critical FL than in an ordinary FL, roughly by an extra power of magnetic correlation length ξ, which diverges at the quantum critical point. However, the enhancement of Γω(KF,PF) is highly nonuniform: It holds only when, for one of the two momentum variables, the distance from a hot spot along the Fermi surface is much larger than for the other one. This fact renders our case different from quantum criticality at small momentum, where the enhancement of Γω(KF,PF) was found to be homogeneous. We show that the charge and spin components of the total vertex function satisfy the universal relations following from the Ward identities related to the conservation of the particle number and the total spin. We show that in a critical FL, the Ward identity involves Γω(KF,PF) taken between particles on the FS. We find that the charge and spin components of

  20. Nature of an intermediate non-Fermi liquid state in Ge-substituted YbRh2Si2: Fermionized skyrmions, Lifshitz transition, skyrmion liquid, and Gruneisen ratio

    NASA Astrophysics Data System (ADS)

    Kim, Ki-Seok

    2012-10-01

    We propose a skyrmion liquid state for the non-Fermi liquid (NFL) phase in Ge-substituted YbRh2Si2, where skyrmions form their Fermi surface, argued to result from the strongly coupled nature between skyrmions and itinerant electrons. The fermionized skyrmion theory identifies the antiferromagnetic (AF) transition with the Lifshitz transition, where the quantum critical point (QCP) is characterized by the dynamical critical exponent z=2. Nonlocal interactions between skyrmions allow a critical line above the AF QCP, which originates from the Kondo-coupling effect with itinerant electrons. This critical line is described by the skyrmion liquid state, which results in Landau damping for spin fluctuations, thus characterized by z=3. As a result, the Gruneisen ratio is predicted to change from ˜T-1 at the AF QCP to ˜T-2/3 in the NFL phase.

  1. Non-Fermi-liquid and topological states with strong spin-orbit coupling.

    PubMed

    Moon, Eun-Gook; Xu, Cenke; Kim, Yong Baek; Balents, Leon

    2013-11-15

    We argue that a class of strongly spin-orbit-coupled materials, including some pyrochlore iridates and the inverted band gap semiconductor HgTe, may be described by a minimal model consisting of the Luttinger Hamiltonian supplemented by Coulomb interactions, a problem studied by Abrikosov and collaborators. It contains twofold degenerate conduction and valence bands touching quadratically at the zone center. Using modern renormalization group methods, we update and extend Abrikosov's classic work and show that interactions induce a quantum critical non-Fermi-liquid phase, stable provided time-reversal and cubic symmetries are maintained. We determine the universal power-law exponents describing various observables in this Luttinger-Abrikosov-Beneslavskii state, which include conductivity, specific heat, nonlinear susceptibility, and the magnetic Gruneisen number. Furthermore, we determine the phase diagram in the presence of cubic and/or time-reversal symmetry breaking perturbations, which includes a topological insulator and Weyl semimetal phases. Many of these phases possess an extraordinarily large anomalous Hall effect, with the Hall conductivity scaling sublinearly with magnetization σ(xy)∼M0.51.

  2. Ground-state and dynamical properties of two-dimensional dipolar Fermi liquids

    SciTech Connect

    Abedinpour, Saeed H.; Asgari, Reza; Tanatar, B.; Polini, Marco

    2014-01-15

    We study the ground-state properties of a two-dimensional spin-polarized fluid of dipolar fermions within the Euler–Lagrange Fermi-hypernetted-chain approximation. Our method is based on the solution of a scattering Schrödinger equation for the “pair amplitude” √(g(r)), where g(r) is the pair distribution function. A key ingredient in our theory is the effective pair potential, which includes a bosonic term from Jastrow–Feenberg correlations and a fermionic contribution from kinetic energy and exchange, which is tailored to reproduce the Hartree–Fock limit at weak coupling. Very good agreement with recent results based on quantum Monte Carlo simulations is achieved over a wide range of coupling constants up to the liquid-to-crystal quantum phase transition. Using the fluctuation–dissipation theorem and a static approximation for the effective inter-particle interactions, we calculate the dynamical density–density response function, and furthermore demonstrate that an undamped zero-sound mode exists for any value of the interaction strength, down to infinitesimally weak couplings. -- Highlights: •We have studied the ground state properties of a strongly correlated two-dimensional fluid of dipolar fermions. •We have calculated the effective inter-particle interaction and the dynamical density–density response function. •We have shown that an undamped zero sound mode exists at any value of the interaction strength.

  3. Extremely Correlated Fermi Liquid theory: Imposing the hole density sum-rule

    NASA Astrophysics Data System (ADS)

    Shastry, B. Sriram

    The analytical theory of extremely strongly correlated Fermi liquids (ECFL) for the large U models, when applied to Cuprate superconductors in the nodal direction, provides ARPES spectral line shapes that are very close to experiments. Approximate lowest order calculations within this formalism also closely reproduce the spectral line shapes for the single impurity Anderson model found using the Numerical Renormalization Group. Similarly excellent comparison is possible with the Dynamical Mean Field Theory self energy for the Hubbard model in high dimensions. However these calculations yields too large an energy scale for frequency dependence, in the proximity of integer (or Mott) filling. We show that the theory permits the imposition of sum rules for hole density, rather than the electron density used earlier, on the Greens functions of the theory. The numerical results of these variants are presented, and compared to the earlier calculations. The new results go a long way towards resolving the energy scale problem, while retaining the excellence of line shapes. The work at UCSC was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES) under Award # FG02-06ER46319.

  4. Non-Fermi Liquid Regimes and Superconductivity in the Low Temperature Phase Diagrams of Strongly Correlated d- and f-Electron Materials

    NASA Astrophysics Data System (ADS)

    Brian Maple, M.; Baumbach, Ryan E.; Butch, Nicholas P.; Hamlin, James J.; Janoschek, Marc

    2010-10-01

    Standard models for simple metals and insulators often fail for systems based on elements with unstable d- or f-electron shells, where strong electronic correlations can generate new and unexpected states of matter. Such a scenario can often be induced when a magnetic phase transition is tuned to absolute zero temperature by an external control parameter such as chemical composition, pressure or magnetic field. At the resulting quantum critical point (QCP), emergent phenomena, such as unconventional superconductivity and novel magnetic phases are frequently observed. The temperature and energy dependences of the physical properties are also found to deviate from expectations for a simple Fermi liquid. This “non-Fermi-liquid” (NFL) behavior is commonly manifested as weak power laws and logarithmic divergences in the physical properties at low temperatures and is often found in a V-shaped region near a QCP, which has become the “classic” QCP phase diagram. However, there is also a growing number of materials where the NFL behavior either occurs far away from the QCP, within an ordered phase, or may not be associated with any putative QCP. Thus, after nearly 20 years of research, it remains unknown whether NFL physics is universal, or if a multitude of unique subclasses exist. In this article, we review research that has primarily been carried out in our laboratory on systems that exhibit NFL behavior that does not conform to the “classic” QCP scenario.

  5. Investigation of fermionic pairing on tight binding lattice for low dimensional systems - Fermi liquid vs. Luttinger-Tomonaga liquid

    NASA Astrophysics Data System (ADS)

    Roy Chowdhury, Soumi; Chaudhury, Ranjan

    2015-05-01

    Cooper's original one pair problem in continuum is revisited here corresponding to a lattice of tight binding nature, with an aim to investigate superconductivity in low dimensional systems. An electronic type of boson mediated attraction in a passive Fermi sea-like background is considered for the pairing mechanism with the non-trivial energy dependence of the electronic density of states taken into account in the calculation in a rigorous way. Some of the very important electronic and optical properties in the normal phase of quasi one dimensional organic superconductors are used for the development of the formalism and calculations. The results of our calculations show that a realistic fermionic pair formation is indeed possible with some constraints, without any necessity at all of invoking Luttinger-Tomonaga liquid (LTL) theory. Similarities emerge in the physical properties of the electron pair formed from Cooper's treatment corresponding to continuum and ours, excepting the striking difference appearing in the form of occurrences of a maximum allowed band filling for pairing and of an upper bound of the pairing energy found in our approach.

  6. Quadrupole-driven non-Fermi-liquid and magnetic-field-induced heavy fermion states in a non-Kramers doublet system

    NASA Astrophysics Data System (ADS)

    Onimaru, T.; Izawa, K.; Matsumoto, K. T.; Yoshida, T.; Machida, Y.; Ikeura, T.; Wakiya, K.; Umeo, K.; Kittaka, S.; Araki, K.; Sakakibara, T.; Takabatake, T.

    2016-08-01

    Orbital degrees of freedom in condensed matter could play important roles in forming a variety of exotic electronic states by interacting with conduction electrons. In 4 f -electron systems, because of strong intra-atomic spin-orbit coupling, an orbitally degenerate state inherently carries quadrupolar degrees of freedom. The present work has focused on a purely quadrupole-active system PrIr2Zn20 showing superconductivity in the presence of an antiferroquadrupole order at TQ=0.11 K. We observed non-Fermi-liquid (NFL) behaviors emerging in the electrical resistivity ρ and the 4 f contribution to the specific heat, C4 f, in the paramagnetic state at T > TQ. Moreover, in magnetic fields B ≤6 T, all data sets of ρ (T ) and C4 f(T ) are well scaled with characteristic temperatures T0's. This observation of the NFL state in the nonmagnetic quadrupole-active system has an origin intrinsically different from that observed in the vicinity of the conventional quantum critical point. It implies possible formation of a quadrupole Kondo lattice resulting from hybridization between the quadrupoles and the conduction electrons with an energy scale of kBT0 . At T ≤0.13 K, ρ (T ) and C4 f(T ) exhibit anomalies as B approaches 5 T. This is the manifestation of a field-induced crossover toward a Fermi-liquid ground state in the quadrupole Kondo lattice.

  7. Fluctuations and phase transitions in Larkin-Ovchinnikov liquid-crystal states of a population-imbalanced resonant Fermi gas

    NASA Astrophysics Data System (ADS)

    Radzihovsky, Leo

    2011-08-01

    Motivated by a realization of imbalanced Feshbach-resonant atomic Fermi gases, we formulate a low-energy theory of the Fulde-Ferrell and the Larkin-Ovchinnikov (LO) states and use it to analyze fluctuations, stability, and phase transitions in these enigmatic finite momentum-paired superfluids. Focusing on the unidirectional LO pair-density-wave state, which spontaneously breaks the continuous rotational and translational symmetries, we show that it is characterized by two Goldstone modes, corresponding to a superfluid phase and a smectic phonon. Because of the liquid-crystalline “softness” of the latter, at finite temperature the three-dimensional state is characterized by a vanishing LO order parameter, quasi-Bragg peaks in the structure and momentum distribution functions, and a “charge”-4, paired-Cooper-pairs, off-diagonal long-range order, with a superfluid-stiffness anisotropy that diverges near a transition into a nonsuperfluid state. In addition to conventional integer vortices and dislocations, the LO superfluid smectic exhibits composite half-integer vortex-dislocation defects. A proliferation of defects leads to a rich variety of descendant states, such as the charge-4 superfluid and Fermi-liquid nematics and topologically ordered nonsuperfluid states, that generically intervene between the LO state and the conventional superfluid and the polarized Fermi liquid at low and high imbalance, respectively. The fermionic sector of the LO gapless superconductor is also quite unique, exhibiting a Fermi surface of Bogoliubov quasiparticles associated with the Andreev band of states, localized on the array of the LO domain walls.

  8. Fluctuations and phase transitions in Larkin-Ovchinnikov liquid-crystal states of a population-imbalanced resonant Fermi gas

    SciTech Connect

    Radzihovsky, Leo

    2011-08-15

    Motivated by a realization of imbalanced Feshbach-resonant atomic Fermi gases, we formulate a low-energy theory of the Fulde-Ferrell and the Larkin-Ovchinnikov (LO) states and use it to analyze fluctuations, stability, and phase transitions in these enigmatic finite momentum-paired superfluids. Focusing on the unidirectional LO pair-density-wave state, which spontaneously breaks the continuous rotational and translational symmetries, we show that it is characterized by two Goldstone modes, corresponding to a superfluid phase and a smectic phonon. Because of the liquid-crystalline ''softness'' of the latter, at finite temperature the three-dimensional state is characterized by a vanishing LO order parameter, quasi-Bragg peaks in the structure and momentum distribution functions, and a ''charge''-4, paired-Cooper-pairs, off-diagonal long-range order, with a superfluid-stiffness anisotropy that diverges near a transition into a nonsuperfluid state. In addition to conventional integer vortices and dislocations, the LO superfluid smectic exhibits composite half-integer vortex-dislocation defects. A proliferation of defects leads to a rich variety of descendant states, such as the charge-4 superfluid and Fermi-liquid nematics and topologically ordered nonsuperfluid states, that generically intervene between the LO state and the conventional superfluid and the polarized Fermi liquid at low and high imbalance, respectively. The fermionic sector of the LO gapless superconductor is also quite unique, exhibiting a Fermi surface of Bogoliubov quasiparticles associated with the Andreev band of states, localized on the array of the LO domain walls.

  9. Quantitative analysis of Sr2RuO4 angle-resolved photoemission spectra: Many-body interactions in a model Fermi liquid

    SciTech Connect

    Ingle, N.J.C.

    2010-04-15

    Angle-resolved photoemission spectroscopy (ARPES) spectra hold a wealth of information about the many-body interactions in a correlated material. However, the quantitative analysis of ARPES spectra to extract the various coupling parameters in a consistent manner is extremely challenging, even for a model Fermi liquid system. We propose a fitting procedure which allows quantitative access to the intrinsic line shape, deconvolved of energy and momentum resolution effects, of the correlated two-dimensional material Sr2RuO4. In correlated two-dimensional materials, we find an ARPES linewidth that is narrower than its binding energy, a key property of quasiparticles within Fermi liquid theory. We also find that when the electron-electron scattering component is separated from the electron-phonon and impurity scattering terms, it decreases with a functional form compatible with Fermi liquid theory as the Fermi energy is approached. In combination with the previously determined Fermi surface, these results give a complete picture of a Fermi liquid system via ARPES. Furthermore, we show that the magnitude of the extracted imaginary part of the self-energy is in remarkable agreement with DC transport measurements.

  10. Fermi liquid-to-Bose condensate crossover in a two-dimensional ultracold gas experiment

    NASA Astrophysics Data System (ADS)

    Barmashova, T. V.; Mart'yanov, K. A.; Makhalov, V. B.; Turlapov, A. V.

    2016-02-01

    By controling interparticle interactions, it is possible to transform a fermionic system into a bosonic system and vice versa, while preserving quantum degeneracy. Evidence of such a transformation may be found by monitoring the pressure and interference. The Fermi pressure is an indication of the fermion?ic character of a system, while the interference implies a nonzero order parameter and Bose condensation. Lowering from three to two spatial dimensions introduces new physics and makes the system more difficult to describe due to the increased fluctuations and the reduced applicability of mean field methods. An experiment with a two-dimensional ultracold atomic gas shows a crossover between the Bose and Fermi limits, as evident from the value of pressure and from the interference pattern, and provides data to test models of 2D Fermi and Bose systems, including the most-difficult-to-model strongly coupled systems.

  11. Doping Dependence of the Electronic Interactions in Bi-2212 Cuprate Superconductors: Doped Antiferromagnets or Antiferromagnetic Fermi Liquids?

    SciTech Connect

    Ruebhausen, M.; Hammerstein, O.A.; Bock, A.; Merkt, U.; Rieck, C.T.; Guptasarma, P.; Hinks, D.G.; Klein, M.V.

    1999-06-01

    Electron-electron interactions in overdoped Bi-2212 are studied by inelastic light scattering. The optimally to slightly overdoped compounds exhibit two-magnon excitations with a dependence on the incident photon energy typical for doped antiferromagnets. For more overdoped samples, no two-magnon excitation is visible, indicating an antiferromagnetic correlation below twice the lattice parameter. In the same samples, the gap excitation shows a resonance similar to the two-magnon excitation. We interpret our results as a development towards a correlated Fermi liquid when the doping is increased. {copyright} {ital 1999} {ital The American Physical Society}

  12. Electronic specific heat enhancement in the half-metallic ferromagnet Cro2 explained by Fermi Liquid Theory

    NASA Astrophysics Data System (ADS)

    Chura, Raul; Bedell, Kevin

    2007-03-01

    Available data on the electronic specific heat of the half-metallic ferromagnet (HMF) CrO2, show that the obtained experimental values are systematically greater than the corresponding theoretical ones calculated through various band theory methods. This discrepancy is due to the presence of many-electron correlation effects (spin fluctuations, strong electron-magnon scattering) which are not taken into account in the band theory calculations. A renormalization of the band theory results is therefore needed to account for the observed enhancement in the value of the specific heat. A microscopic many-electron approach has been proposed and explains the referred enhancement in terms of non-quasiparticle effects. It has been argued that Fermi liquid theory is not sufficient to provide the appropriate renormalization able to explain the observed enhancement in the electronic specific heat of HMFs. Contrary to this statement, we have shown that the introduction of a spin-dependent density of states, in the framework of the Fermi liquid theory for spin polarized systems, gives place to a renormalization which, indeed, provides a reasonable account of the observed enhancement in the electronic specific heat of the HMF CrO2.

  13. Quantum liquid crystals in an imbalanced Fermi gas: fluctuations and fractional vortices in Larkin-Ovchinnikov states.

    PubMed

    Radzihovsky, Leo; Vishwanath, Ashvin

    2009-07-01

    We develop a low-energy model of an unidirectional Larkin-Ovchinnikov (LO) state. Because the underlying rotational and translational symmetries are broken spontaneously, this gapless superfluid is a smectic liquid crystal, that exhibits fluctuations that are qualitatively stronger than in a conventional superfluid, thus requiring a fully nonlinear description of its Goldstone modes. Consequently, at nonzero temperature the LO superfluid is an algebraic phase even in 3D. It exhibits half-integer vortex-dislocation defects, whose unbinding leads to transitions to a superfluid nematic and other phases. In 2D at nonzero temperature, the LO state is always unstable to a nematic superfluid. We expect this superfluid liquid-crystal phenomenology to be realizable in imbalanced resonant Fermi gases trapped isotropically. PMID:19659128

  14. Quantum Liquid Crystals in an Imbalanced Fermi Gas: Fluctuations and Fractional Vortices in Larkin-Ovchinnikov States

    NASA Astrophysics Data System (ADS)

    Radzihovsky, Leo; Vishwanath, Ashvin

    2009-07-01

    We develop a low-energy model of an unidirectional Larkin-Ovchinnikov (LO) state. Because the underlying rotational and translational symmetries are broken spontaneously, this gapless superfluid is a smectic liquid crystal, that exhibits fluctuations that are qualitatively stronger than in a conventional superfluid, thus requiring a fully nonlinear description of its Goldstone modes. Consequently, at nonzero temperature the LO superfluid is an algebraic phase even in 3D. It exhibits half-integer vortex-dislocation defects, whose unbinding leads to transitions to a superfluid nematic and other phases. In 2D at nonzero temperature, the LO state is always unstable to a nematic superfluid. We expect this superfluid liquid-crystal phenomenology to be realizable in imbalanced resonant Fermi gases trapped isotropically.

  15. Quantum Liquid Crystals in an Imbalanced Fermi Gas: Fluctuations and Fractional Vortices in Larkin-Ovchinnikov States

    SciTech Connect

    Radzihovsky, Leo; Vishwanath, Ashvin

    2009-07-03

    We develop a low-energy model of an unidirectional Larkin-Ovchinnikov (LO) state. Because the underlying rotational and translational symmetries are broken spontaneously, this gapless superfluid is a smectic liquid crystal, that exhibits fluctuations that are qualitatively stronger than in a conventional superfluid, thus requiring a fully nonlinear description of its Goldstone modes. Consequently, at nonzero temperature the LO superfluid is an algebraic phase even in 3D. It exhibits half-integer vortex-dislocation defects, whose unbinding leads to transitions to a superfluid nematic and other phases. In 2D at nonzero temperature, the LO state is always unstable to a nematic superfluid. We expect this superfluid liquid-crystal phenomenology to be realizable in imbalanced resonant Fermi gases trapped isotropically.

  16. Interplay of Superconductivity and Fermi-Liquid Transport in Rh-Doped CaFe2As2 with Lattice-Collapse Transition

    NASA Astrophysics Data System (ADS)

    Danura, Masataka; Kudo, Kazutaka; Oshiro, Yoshihiro; Araki, Shingo; Kobayashi, Tatsuo C.; Nohara, Minoru

    2011-10-01

    Ca(Fe1-xRhx)2As2 undergoes successive phase transitions with increasing Rh doping in the T = 0 limit. The antiferromagnetic-metal phase with orthorhombic structure at 0.00 ≤ x ≤ 0.020 is driven to a superconducting phase with uncollapsed-tetragonal (ucT) structure at 0.020 ≤ x ≤ 0.024; a non-superconducting collapsed-tetragonal (cT) phase takes over at x ≥ 0.024. The breakdown of Fermi-liquid transport is observed in the ucT phase above Tc. In the adjacent cT phase, Fermi-liquid transport is restored along with a disappearance of superconductivity. This interplay of superconductivity and Fermi-liquid transport suggests the essential role of magnetic fluctuations in the emergence of superconductivity in doped CaFe2As2.

  17. Flow behavior in liquid molding

    NASA Technical Reports Server (NTRS)

    Hunston, D.; Phelan, F.; Parnas, R.

    1992-01-01

    The liquid molding (LM) process for manufacturing polymer composites with structural properties has the potential to significantly lower fabrication costs and increase production rates. LM includes both resin transfer molding and structural reaction injection molding. To achieve this potential, however, the underlying science base must be improved to facilitate effective process optimization and implementation of on-line process control. The National Institute of Standards and Technology (NIST) has a major program in LM that includes materials characterization, process simulation models, on-line process monitoring and control, and the fabrication of test specimens. The results of this program are applied to real parts through cooperative projects with industry. The key feature in the effort is a comprehensive and integrated approach to the processing science aspects of LM. This paper briefly outlines the NIST program and uses several examples to illustrate the work.

  18. Classical Behavior of Two-Dimensional Liquid 3He Near a Quantum Critical Point

    NASA Astrophysics Data System (ADS)

    Clark, J. W.; Khodel, V. A.; Zverev, M. V.

    2013-11-01

    Non-Fermi-liquid (NFL) behavior of the specific heat C(T) of two-dimensional (2D) liquid 3He, first uncovered in measurements almost 20 years ago, is explained in terms of intrinsic properties of this system that emerge when its density rises and the liquid becomes strongly correlated. The occurrence of a T-independent β term in C(T) is attributed to satisfaction of the conditions for Dulong-Petit behavior by the boson part of the free energy. This unexpected classicality stems from softening of the transverse zero-sound mode (TZSM) in the density region where the anomaly in C(T), associated with a quantum critical point (QCP), is observed.

  19. Polymer's anchoring behavior in liquid crystal cells

    NASA Astrophysics Data System (ADS)

    Cui, Yue

    The current dissertation mainly discusses about the polymers anchoring behavior in liquid crystal cells in two aspects: surface interaction and bulk interaction. The goal of the research is to understand the fundamental physics of anchoring strength and apply the knowledge to liquid crystal display devices. Researchers proposed two main contributors to the surface anchoring strength: the micro grooves generated by external force and the polymer chain's alignment. Both of them has experimental proofs. In the current study, explorations were made to understand the mechanisms of surface anchoring strength and easy axis of surface liquid crystal provided by rubbed polymer alignment layer. The work includes not only the variation of the alignment layer itself such as thickness(Chapter 3) and polymer side chain (Chapter 5), but also the variation of external conditions such as temperature (Chapter 4) and rubbing condition (Chapter 6). To determine the polar and azimuthal anchoring strengths, Rapini-Papoular's expression was applied. However, it was discovered that higher order terms may be required in order to fit the experimental result or theoretically predict unique anchoring behaviors (Chapter 2, Chapter 6). SEM and AFM technologies were introduced to gather the actual structures of polymer alignment layer and extrapolate the alignment of liquid crystal in a micro scale. The result shows that the anchoring strength can be adjusted by the layer thickness, side chain structure, while the easy axis direction can be adjusted by a second rubbing direction. In addition, different anchoring conditions combined with liquid crystal's elastic energy can generate quite different forms of liquid crystals (Chapter 7). In the study of bulk alignment, the main contrition from the current dissertation is applying the understanding of anchoring behavior to optimizing actual switchable devices. Conventional PDLC performance can be tuned with the knowledge of the polymer and the liquid

  20. Phases of one-dimensional SU(N) cold atomic Fermi gases-From molecular Luttinger liquids to topological phases

    NASA Astrophysics Data System (ADS)

    Capponi, S.; Lecheminant, P.; Totsuka, K.

    2016-04-01

    Alkaline-earth and ytterbium cold atomic gases make it possible to simulate SU(N)-symmetric fermionic systems in a very controlled fashion. Such a high symmetry is expected to give rise to a variety of novel phenomena ranging from molecular Luttinger liquids to (symmetry-protected) topological phases. We review some of the phases that can be stabilized in a one dimensional lattice. The physics of this multi-component Fermi gas turns out to be much richer and more exotic than in the standard SU(2) case. For N > 2, the phase diagram is quite rich already in the case of the single-band model, including a molecular Luttinger liquid (with dominant superfluid instability in the N-particle channel) for incommensurate fillings, as well as various Mott-insulating phases occurring at commensurate fillings. Particular attention will be paid to the cases with additional orbital degree of freedom (which is accessible experimentally either by taking into account two atomic states or by putting atoms in the p-band levels). We introduce two microscopic models which are relevant for these cases and discuss their symmetries and strong coupling limits. More intriguing phase diagrams are then presented including, for instance, symmetry protected topological phases characterized by non-trivial edge states.

  1. Behavior of Collective Cooperation Yielded by Two Update Rules in Social Dilemmas: Combining Fermi and Moran Rules

    NASA Astrophysics Data System (ADS)

    Xia, Cheng-Yi; Wang, Lei; Wang, Juan; Wang, Jin-Song

    2012-09-01

    We combine the Fermi and Moran update rules in the spatial prisoner's dilemma and snowdrift games to investigate the behavior of collective cooperation among agents on the regular lattice. Large-scale simulations indicate that, compared to the model with only one update rule, the cooperation behavior exhibits the richer phenomena, and the role of update dynamics should be paid more attention in the evolutionary game theory. Meanwhile, we also observe that the introduction of Moran rule, which needs to consider all neighbor's information, can markedly promote the aggregate cooperation level, that is, randomly selecting the neighbor proportional to its payoff to imitate will facilitate the cooperation among agents. Current results will contribute to further understand the cooperation dynamics and evolutionary behaviors within many biological, economic and social systems.

  2. The effect of an anti-hydrogen bond on Fermi resonance: A Raman spectroscopic study of the Fermi doublet ν1-ν12 of liquid pyridine

    NASA Astrophysics Data System (ADS)

    Li, Dong-Fei; Gao, Shu-Qin; Sun, Cheng-Lin; Li, Zuo-Wei

    2012-08-01

    The effects of an anti-hydrogen bond on the ν1-ν12 Fermi resonance (FR) of pyridine are experimentally investigated by using Raman scattering spectroscopy. Three systems, pyridine/water, pyridine/formamide, and pyridine/carbon tetrachloride, provide varying degrees of strength for the diluent-pyridine anti-hydrogen bond complex. Water forms a stronger anti-hydrogen bond with pyridine than with formamide, and in the case of adding non-polar solvent carbon tetrachloride, which is neither a hydrogen bond donor nor an acceptor and incapable of forming a hydrogen bond with pyridine, the intermolecular distance of pyridine will increase and the interaction of pyridine molecules will reduce. The dilution studies are performed on the three systems. Comparing with the values of the Fermi coupling coefficient W of the ring breathing mode ν1 and triangle mode ν12 of pyridine at different volume concentrations, which are calculated according to the Bertran equations, in three systems, we find that the solution with the strongest anti-hydrogen bond, water, shows the fastest change in the ν1-ν12 Fermi coupling coefficient W with the volume concentration varying, followed by the formamide and carbon tetrachloride solutions. These results suggest that the stronger anti-hydrogen bond-forming effect will cause a greater reduction in the strength of the ν1-ν12 FR of pyridine. According to the mechanism of the formation of an anti-hydrogen bond in the complexes and the FR theory, a qualitative explanation for the anti-hydrogen bond effect in reducing the strength of the ν1-ν12 FR of pyridine is given.

  3. Perfect-fluid behavior of a dilute Fermi gas near unitary

    NASA Astrophysics Data System (ADS)

    Wlazłowski, Gabriel; Quan, Wei; Bulgac, Aurel

    2015-12-01

    We present an ab initio calculation of the shear viscosity as a function of interaction strength in a two-component unpolarized Fermi gas near the unitary limit, within a finite temperature quantum Monte Carlo (QMC) framework and using the Kubo linear-response formalism. The shear viscosity decreases as we tune the interaction strength 1/a kF from the Bardeen-Cooper-Schrieffer side of the Feshbach resonance towards Bose-Einstein condensation limit and it acquires the smallest value for 1/a kF ≈0.4 , with a minimum value of |η/s|η/s min≈0.2 ℏ/kB , which is about twice as small as the value reported for experiments in quark-gluon plasma QGP ≲0.4 ℏ/kB . The Fermi gas near unitarity thus emerges as the most "perfect fluid" observed so far in nature. The clouds of dilute Fermi gas near unitarity exhibit the unusual attribute that, for the sizes realized so far in the laboratory, or larger (less than 109 atoms), can sustain quantum turbulence below the critical temperature, but at the same time the classical turbulence is suppressed in the normal phase.

  4. Bipolaron-SO(5) non-Fermi liquid in a two-channel Anderson model with phonon-assisted hybridizations

    NASA Astrophysics Data System (ADS)

    Hattori, K.

    2012-06-01

    We analyze non-Fermi liquid (NFL) properties along a line of critical points in a two-channel Anderson model with phonon-assisted hybridizations. We succeed in identifying hidden nonmagnetic SO(5) degrees of freedom for the valence-fluctuation regime, and we analyze the model on the basis of boundary conformal field theory. We find that the NFL spectra along the critical line, which is the same as those in the two-channel Kondo model, can be alternatively derived by a fusion in the nonmagnetic SO(5) sector. The leading irrelevant operators near the NFL fixed points vary as a function of Coulomb repulsion U; operators in the spin sector dominate for large U, while those in the SO(5) sector dominate for small U, and we confirm this variation in our numerical renormalization group calculations. As a result, the thermodynamic singularity for small U differs from that of the conventional two-channel Kondo problem. In particular, the impurity contribution to specific heat is proportional to temperature, and bipolaron fluctuations, which are coupled electron-phonon fluctuations, diverge logarithmically at low temperatures for small U.

  5. Properties of an almost localized Fermi liquid in an applied magnetic field revisited: a statistically consistent Gutzwiller approach.

    PubMed

    Wysokiński, Marcin M; Spałek, Jozef

    2014-02-01

    We discuss the Hubbard model in an applied magnetic field and analyze the properties of neutral spin-[Formula: see text] fermions within the so-called statistically consistent Gutzwiller approximation. The magnetization curve reproduces in a semiquantitative manner the experimental data for liquid (3)He in the regime of moderate correlations and in the presence of a small number of vacant cells, modeled by a non-half-filled band situation, when a small number of vacancies (∼5%) is introduced in the virtual fcc lattice. We also present the results for the magnetic susceptibility and the specific heat, in which a metamagnetic-like behavior is also singled out in a non-half-filled band case.

  6. Retreating behavior of a charged ionic liquid droplet in a dielectric liquid under electric field

    NASA Astrophysics Data System (ADS)

    Ahn, Myung Mo; Im, Do Jin; Kang, In Seok

    2013-11-01

    Ionic liquids show great promise as excellent solvents or catalysts in energy and biological fields due to their unique chemical and physical properties. The ionic liquid droplets in microfluidic systems can also be used as a potential platform for chemical biological reactions. In order to control electrically the ionic liquid droplets in a microfluidic device, the charging characteristics of ionic liquid droplets need to be understood. In this work, the charging characteristics of various ionic liquids are investigated by using the parallel plate electrodes system. Under normal situation, a charged droplet shows bouncing motion between electrodes continuously. However, for some special ionic liquids, interesting retreating behavior of charged ionic liquid droplet has been observed. This retreating behavior of ionic liquid droplet has been analyzed experimentally by the image analysis and the electrometer signal analysis. Based on the hypothesis of charge leakage of the retreating ionic liquid droplets, FT-IR spectroscopy analysis has also been performed. The retreating behavior of ionic liquid droplet is discussed from the intermolecular point of view according to the species of ionic liquids. This research was supported by grant No. 2013R1A1A2011956 funded by the Ministry of Science, ICT and Future Planning (MSIP) and by grant No. 2013R1A1A2010483 funded by the Ministry of Education, Science and Technology (MEST) through the NRF.

  7. Evaporative mass transfer behavior of a complex immiscible liquid.

    PubMed

    McColl, Colleen M; Johnson, Gwynn R; Brusseau, Mark L

    2008-09-01

    A series of laboratory experiments was conducted with a multiple-component immiscible liquid, collected from the Picillo Farm Superfund Site in Rhode Island, to examine liquid-vapor mass-transfer behavior. The immiscible liquid, which comprises solvents, oils, pesticides, PCBs, paint sludges, explosives, and other compounds, was characterized using gas chromatography and gas chromatography/mass spectrometry to determine mole fractions of selected constituents. Batch experiments were conducted to evaluate equilibrium phase-partitioning behavior. Two sets of air-stripping column studies were conducted to examine the mass-transfer dynamics of five selected target compounds present in the immiscible-liquid mixture. One set of column experiments was designed to represent a system with free-phase immiscible liquid present; the other was designed to represent a system with a residual phase of immiscible liquid. Initial elution behavior of all target components generally appeared to be ideal for both systems, as the initial vapor-phase concentrations were similar to vapor-phase concentrations measured for the batch experiment and those estimated using Raoult's law (incorporating the immiscible-liquid composition data). Later-stage removal of 1,2-dichlorobenzene appeared to be rate limited for the columns containing free-phase immiscible liquid and no porous medium. Conversely, evaporative mass transfer appeared to be ideal throughout the experiment conducted with immiscible liquid distributed relatively uniformly as a residual phase within a sandy porous medium.

  8. Evaporative Mass Transfer Behavior of a Complex Immiscible Liquid

    PubMed Central

    McColl, Colleen M.; Johnson, Gwynn R.; Brusseau, Mark L.

    2010-01-01

    A series of laboratory experiments was conducted with a multiple-component immiscible liquid, collected from the Picillo Farm Superfund Site in Rhode Island, to examine liquid-vapor mass-transfer behavior. The immiscible liquid, which comprises solvents, oils, pesticides, PCBs, paint sludges, explosives, and other compounds, was characterized using gas chromatography and gas chromatography/mass spectrometry to determine mole fractions of selected constituents. Batch experiments were conducted to evaluate equilibrium phase-partitioning behavior. Two sets of air-stripping column studies were conducted to examine the mass-transfer dynamics of five selected target compounds present in the immiscible-liquid mixture. One set of column experiments was designed to represent a system with free-phase immiscible liquid present; the other was designed to represent a system with a residual phase of immiscible liquid. Initial elution behavior of all target components generally appeared to be ideal for both systems, as the initial vapor-phase concentrations were similar to vapor-phase concentrations measured for the batch experiment and those estimated using Raoult’s law (incorporating the immiscible-liquid composition data). Later-stage removal of 1,2-dichlorobenzene appeared to be rate limited for the columns containing free-phase immiscible liquid and no porous medium. Conversely, evaporative mass transfer appeared to be ideal throughout the experiment conducted with immiscible liquid distributed relatively uniformly as a residual phase within a sandy porous medium. PMID:18614196

  9. Evaporative mass transfer behavior of a complex immiscible liquid.

    PubMed

    McColl, Colleen M; Johnson, Gwynn R; Brusseau, Mark L

    2008-09-01

    A series of laboratory experiments was conducted with a multiple-component immiscible liquid, collected from the Picillo Farm Superfund Site in Rhode Island, to examine liquid-vapor mass-transfer behavior. The immiscible liquid, which comprises solvents, oils, pesticides, PCBs, paint sludges, explosives, and other compounds, was characterized using gas chromatography and gas chromatography/mass spectrometry to determine mole fractions of selected constituents. Batch experiments were conducted to evaluate equilibrium phase-partitioning behavior. Two sets of air-stripping column studies were conducted to examine the mass-transfer dynamics of five selected target compounds present in the immiscible-liquid mixture. One set of column experiments was designed to represent a system with free-phase immiscible liquid present; the other was designed to represent a system with a residual phase of immiscible liquid. Initial elution behavior of all target components generally appeared to be ideal for both systems, as the initial vapor-phase concentrations were similar to vapor-phase concentrations measured for the batch experiment and those estimated using Raoult's law (incorporating the immiscible-liquid composition data). Later-stage removal of 1,2-dichlorobenzene appeared to be rate limited for the columns containing free-phase immiscible liquid and no porous medium. Conversely, evaporative mass transfer appeared to be ideal throughout the experiment conducted with immiscible liquid distributed relatively uniformly as a residual phase within a sandy porous medium. PMID:18614196

  10. Particle Behavior at Anisotropically Curved Liquid Interfaces

    NASA Astrophysics Data System (ADS)

    McEnnis, Kathleen; Zeng, Chuan; Davidovitch, Benny; Dinsmore, Anthony; Russell, Thomas

    2011-03-01

    A particle bound to an anisotropically curved liquid interface, such as a cylinder or catenoid, cannot maintain a constant contact angle without deforming the interface. Theory suggests that the particles will experience a force that depends on the interfacial shape and migrate to minimize the total interfacial energy. To test these predictions, particles were deposited on top of liquid semi-cylinders of ionic liquid or melted polystyrene confined on chemically patterned surfaces. Particles were also deposited on liquid catenoid structures created by placing a melted polymer film under an electric field. The location of the particles on these structures was observed by optical, confocal, and scanning electron microscopy. The implications for the directed assembly of particles and stability of Pickering emulsions are also discussed.

  11. Low-energy physics of the t -J model in d =∞ using extremely correlated Fermi liquid theory: Cutoff second-order equations

    NASA Astrophysics Data System (ADS)

    Shastry, B. Sriram; Perepelitsky, Edward

    2016-07-01

    We present the results for the low-energy properties of the infinite-dimensional t -J model with J =0 , using O (λ2) equations of the extremely correlated Fermi liquid formalism. The parameter λ ∈[0 ,1 ] is analogous to the inverse spin parameter 1 /(2 S ) in quantum magnets. The present analytical scheme allows us to approach the physically most interesting regime near the Mott insulating state n ≲1 . It overcomes the limitation to low densities n ≲0.7 of earlier calculations, by employing a variant of the skeleton graph expansion, and a high-frequency cutoff that is essential for maintaining the known high-T entropy. The resulting quasiparticle weight Z , the low ω ,T self-energy, and the resistivity are reported. These are quite close at all densities to the exact numerical results of the U =∞ Hubbard model, obtained using the dynamical mean field theory. The present calculation offers the advantage of generalizing to finite T rather easily, and allows the visualization of the loss of coherence of Fermi liquid quasiparticles by raising T . The present scheme is generalizable to finite dimensions and a nonvanishing J .

  12. Nearly ferromagnetic Fermi-liquid behaviour in YFe2Zn20 and high-temperature ferromagnetism of GdFe2Zn20

    NASA Astrophysics Data System (ADS)

    Jia, S.; Bud'Ko, S. L.; Samolyuk, G. D.; Canfield, P. C.

    2007-05-01

    One of the historic goals of alchemy was to turn base elements into precious ones. Although the practice of alchemy has been superseded by chemistry and solid-state physics, the desire to dramatically change or tune the properties of a compound, preferably through small changes in stoichiometry or composition, remains. This desire becomes even more compelling for compounds that can be tuned to extremes in behaviour. Here, we report that the RT2Zn20 (R=rare earth and T=transition metal) family of compounds manifests exactly this type of versatility, even though they are more than 85% Zn. By tuning T, we find that YFe2Zn20 is closer to ferromagnetism than elemental Pd, the classic example of a nearly ferromagnetic Fermi liquid. By submerging Gd in this highly polarizable Fermi liquid, we tune the system to a remarkably high-temperature ferromagnetic (TC=86K) state for a compound with less than 5% Gd. Although this is not quite turning lead into gold, it is essentially tuning Zn to become a variety of model compounds.

  13. [Effect on Fermi Resonance by Some External Fields: Investigation of Fermi Resonance According to Raman Spectra].

    PubMed

    Jiang, Xiu-lan; Sun, Cheng-lin; Zhou, Mi; Li, Dong-fei; Men, Zhi-wei; Li, Zuo-wei; Gao, Shu-qin

    2015-03-01

    Fermi resonance is a phenomenon of molecular vibrational coupling and energy transfer occurred between different groups of a single molecule or neighboring molecules. Many properties of Fermi resonance under different external fields, the investigation method of Raman spectroscopy as well as the application of Fermi resonance, etc need to be developed and extended further. In this article the research results and development about Fermi resonance obtained by Raman spectral technique were introduced systematically according to our work and the results by other researchers. Especially, the results of the behaviors of intramolecular and intermolecular Fermi resonance of some molecules under some external fields such as molecular field, pressure field and temperature field, etc were investigated and demonstrated in detail according to the Raman spectra obtained by high pressure DAC technique, temperature variation technique as well as the methods we planed originally in our group such as solution concentration variation method and LCOF resonance Raman spectroscopic technique, and some novel properties of Fermi resonance were found firstly. Concretely, (1) Under molecular field. a. The Raman spectra of C5H5 N in CH3 OH and H2O indicates that solvent effect can influence Fermi resonance distinctly; b. The phenomena of the asymmetric movement of the Fermi resonance doublets as well as the fundamental involved is tuned by the Fermi resonance which had not been found by other methods were found firstly by our variation solution concentration method; c. The Fermi resonance properties can be influenced distinctly by the molecular group reorganization induced by the hydrogen bond and anti-hydrogen bond in solution; d. Fermi resonance can occurred between C7 H8 and m-C8H10, and the Fermi resonance properties behave quite differently with the solution concentration; (2) Under pressure field. a. The spectral lines shift towards high wavenumber with increasing pressure, and

  14. Thermal behaviors of liquid La-based bulk metallic glasses

    SciTech Connect

    Zhang, D. W.; Wang, X. D. E-mail: jiangjz@zju.edu.cn; Lou, H. B.; Cao, Q. P.; Jiang, J. Z. E-mail: jiangjz@zju.edu.cn; Wang, L. W.; Zhang, D. X.

    2014-12-14

    Thermal behaviors of liquid La-based bulk metallic glasses have been measured by using the dilatometer with a self-sealed sample cell. It is demonstrated that the strong glass forming liquid not only has the small thermal expansion coefficient but also shows the slow variation rate. Moreover, the strong glass former has relatively dense atomic packing and also small density change in the liquid state. The results suggest that the high glass forming ability of La-based metallic glasses would be closely related to the slow atomic rearrangements in liquid melts.

  15. Cavitation bubble behavior inside a liquid jet

    NASA Astrophysics Data System (ADS)

    Robert, Etienne; Lettry, Jacques; Farhat, Mohamed; Monkewitz, Peter A.; Avellan, François

    2007-06-01

    The growth and collapse of laser-induced vapor cavities inside axisymmetric free-falling liquid water jets have been studied. Bubbles of different size are generated at various distances from the jet axis and the effects on the jet interface are recorded by means of ultrafast cinematography. The configuration is characterized by two dimensionless parameters: the bubble to jet diameter ratio δ and the eccentricity coefficient ɛ defined as the radius of bubble generation divided by the jet radius. For high δ and ɛ, microjets and droplets are ejected from the liquid jet at speeds exceeding 100m/s. The observed jet fragmentation shows similarities with experiments conducted on a liquid mercury jet hit by a pulsed proton beam, a candidate configuration for future accelerator based facilities.

  16. Remembering Fermi

    SciTech Connect

    Cronin, James

    2005-03-30

    A combination of the discovery of nuclear fission and the circumstances of the 2nd World War brought Enrico Fermi to Chicago, where he led the team that produced the first controlled, self-sustained nuclear chain reaction. Following the war in 1945 Chancellor Hutchins, William Zachariasen, and Walter Bartky convinced Fermi to accept a professorship at the University of Chicago, where the Institute for Nuclear Studies was established. Fermi served as the leading figure in surely the greatest collection of scientists the world has ever seen. Fermi's tenure at Chicago was cut short by his death in 1954. My talk will concentrate on the years 1945-54. Examples of his research notebooks, his speeches, his teaching, and his correspondence will be discussed.

  17. Behavior of liquid hydrogen inside an ICF target

    NASA Technical Reports Server (NTRS)

    Kim, K.; Mok, L.; Bernat, T.

    1982-01-01

    The configuration of liquid hydrogen inside spherical glass shell ICF target was studied both theoretically and experimentally. Because of the zero contact angle between the .D2 liquid and glass substrate and the limited wetting surface that is continuous, the liquid hydrogen completely covers the interior of the glass shell, resulting in the formation of a void at the center. For this reason, the present problem distinguishes itself from that for a sessile drop sitting on a flat surface. A theory was formulated to calculate the liquid hydrogen configuration by including the London-dispersion force between the liquid and the substrate molecules. The net result is an augmented Bashforth-Adams equation appropriate to a spherical substrate, which is considered to be the major contribution of the present work. Preliminary calculations indicate that this equation accurately models the liquid hydrogen behavior inside a spherical microshell.

  18. Holographic Quantum Liquid

    SciTech Connect

    Karch, A.; Son, D. T.; Starinets, A. O.

    2009-02-06

    Quantum liquids are characterized by the distinctive properties such as the low-temperature behavior of heat capacity and the spectrum of low-energy quasiparticle excitations. In particular, at low temperature, Fermi liquids exhibit the zero sound, predicted by Landau in 1957 and subsequently observed in liquid He-3. In this Letter, we ask whether such characteristic behavior is present in theories with a holographically dual description. We consider a class of gauge theories with fundamental matter fields whose holographic dual in the appropriate limit is given in terms of the Dirac-Born-Infeld action in anti-de Sitter space. We find that these systems also exhibit a sound mode at zero temperature despite having a non-Fermi-liquid behavior of the specific heat. These properties suggest that holography identifies a new type of quantum liquid which potentially could be experimentally realized in strongly correlated systems.

  19. Unconventional Fermi surface in an insulating state

    SciTech Connect

    Harrison, Neil; Tan, B. S.; Hsu, Y. -T.; Zeng, B.; Hatnean, M. Ciomaga; Zhu, Z.; Hartstein, M.; Kiourlappou, M.; Srivastava, A.; Johannes, M. D.; Murphy, T. P.; Park, J. -H.; Balicas, L.; Lonzarich, G. G.; Balakrishnan, G.; Sebastian, Suchitra E.

    2015-07-17

    Insulators occur in more than one guise; a recent finding was a class of topological insulators, which host a conducting surface juxtaposed with an insulating bulk. Here, we report the observation of an unusual insulating state with an electrically insulating bulk that simultaneously yields bulk quantum oscillations with characteristics of an unconventional Fermi liquid. We present quantum oscillation measurements of magnetic torque in high-purity single crystals of the Kondo insulator SmB6, which reveal quantum oscillation frequencies characteristic of a large three-dimensional conduction electron Fermi surface similar to the metallic rare earth hexaborides such as PrB6 and LaB6. As a result, the quantum oscillation amplitude strongly increases at low temperatures, appearing strikingly at variance with conventional metallic behavior.

  20. Superconductivity and non-Fermi-liquid behavior in Ce1-xYbxCoIn5

    NASA Astrophysics Data System (ADS)

    Shu, L.; Gonzales, E.; Huang, K.; Sayles, T. A.; Baumbach, R. E.; Hamlin, J. J.; Zocco, D. A.; McElroy, C. A.; Maple, M. B.; Paglione, J.; O'Brien, J.; Ho, P.-C.

    2010-03-01

    Single-crystals of Ce1-xYbxCoIn5 were investigated by specific heat CP(T), electrical resistivity ρ(T), and magnetic susceptibility χ(T) measurements as a function of x. As Yb is substituted for Ce, Tc(x) is gradually suppressed to 0.9 K at x=0.8. In the low Yb concentration region near x = 0.1, there is a feature in the lattice constants and residual resistivity, a crossover in the anisotropy of χ(T), the development of NFL T-dependences of χ(T) and CP(T) in the normal state,indicating the existence of a quantum critical point, and a plateau in Tc(x). In the high Yb concentration region near x=0.8, there is an abrupt drop in the lattice parameters that is accompanied by a precipitous drop in Tc(x). The features in the physical properties at x=0.1 and 0.8 indicate the occurrence of some incipient electronic phase transitions, possibly involving the Ce and Yb valences at these compositions.

  1. Evolution from a non-Fermi liquid Kondo lattice to intermediate valence behaviour in CeRhSn(1-x)In(x).

    PubMed

    Ślebarski, A; Fijałkowski, M; Goraus, J

    2012-03-28

    We present investigations of the magnetic and electric transport properties, specific heat, and electronic structure of the intermetallic and strongly correlated system of CeRhSn(1-x)In(x) compounds. The main goal of this paper is to determine the hybridization energy between the f electron and conduction electron states, V(cf), and its influence on the ground state properties of the system. The complementary experimental data are discussed on the basis of the Anderson model for a periodic Kondo lattice. CeRhSn is known as a non-Fermi liquid, while CeRhIn is a valence fluctuating system. We discuss the ground state properties of CeRhSn(1-x)In(x) and compare the results with those obtained for the doped Ce-based Kondo insulators.

  2. Evolution from a non-Fermi liquid Kondo lattice to intermediate valence behaviour in CeRhSn(1-x)In(x).

    PubMed

    Ślebarski, A; Fijałkowski, M; Goraus, J

    2012-03-28

    We present investigations of the magnetic and electric transport properties, specific heat, and electronic structure of the intermetallic and strongly correlated system of CeRhSn(1-x)In(x) compounds. The main goal of this paper is to determine the hybridization energy between the f electron and conduction electron states, V(cf), and its influence on the ground state properties of the system. The complementary experimental data are discussed on the basis of the Anderson model for a periodic Kondo lattice. CeRhSn is known as a non-Fermi liquid, while CeRhIn is a valence fluctuating system. We discuss the ground state properties of CeRhSn(1-x)In(x) and compare the results with those obtained for the doped Ce-based Kondo insulators. PMID:22369764

  3. Similarity of the leading contributions to the self-energy and the thermodynamics in two- and three-dimensional Fermi Liquids

    SciTech Connect

    Coffey, D.; Bedell, K.S.

    1993-01-01

    We compare the self-energy and entropy of a two- and three-dimensional Fermi Liquids (FLs) using a model with a contact interaction between fermions. For a two-dimensional (2D) FL we find that there are T[sup 2] contributions to the entropy from interactions separate from those due to the collective modes. These T[sup 2] contributions arise from nonanalytic corrections to the real part of the self-energy and areanalogous to T[sup 3]lnT contributions present in the entropy of a three-dimensional (3D) FL. The difference between the 2D and 3D results arises solely from the different phase space factors.

  4. Similarity of the leading contributions to the self-energy and the thermodynamics in two- and three-dimensional Fermi Liquids

    SciTech Connect

    Coffey, D.; Bedell, K.S.

    1993-05-01

    We compare the self-energy and entropy of a two- and three-dimensional Fermi Liquids (FLs) using a model with a contact interaction between fermions. For a two-dimensional (2D) FL we find that there are T{sup 2} contributions to the entropy from interactions separate from those due to the collective modes. These T{sup 2} contributions arise from nonanalytic corrections to the real part of the self-energy and areanalogous to T{sup 3}lnT contributions present in the entropy of a three-dimensional (3D) FL. The difference between the 2D and 3D results arises solely from the different phase space factors.

  5. Solidification behavior of undercooled liquid aluminum oxide

    SciTech Connect

    Weber, J.K.R.; Anderson, C.D.; Merkley, D.R.; Nordine, P.C.

    1995-03-01

    Solidification of aluminum oxide from undercooled melts was investigated in containerless experiments. Specimens were levitated in a gas jet, stabilized with an acoustic positioning device, and melted with cw CO{sub 2} laser beams. Cooling curves were obtained by optical pyrometry when the laser intensity was reduced. The materials examined were high-purity Verneuil sapphire, 99.5% polycrystalline alumina, and oxide materials recovered from the effluent of an aluminum-fueled rocket motor. The degree of undercooling, the apparent temperature behavior during the thermal arrest on solidification, and the structure of the materials formed were different in argon and oxygen atmospheres. Undercooling of the sapphire and alumina materials was 360 {+-} 10 K in an oxygen atmosphere and approximately 450 K in argon. Melting and solidification of high-purity sapphire resulted in a dendritic and porous polycrystalline material in oxygen. Dense, larger crystals were obtained in argon. Products formed from 99.5% alumina were discolored and the cores were white, indicating impurity segregation effects. More reproducible behavior was observed for the sapphire and 99.5% alumina than for the tungsten-contaminated rocket motor effluent materials.

  6. Discontinuous behavior of liquids between parallel and tilted plates

    SciTech Connect

    Concus, P.; Finn, R.

    1998-01-01

    Discontinuous behavior of liquids between parallel and tilted plates in the absence of gravity is discussed. A principal finding, derived mathematically from the classical Young{endash}Laplace{endash}Gauss formulation for capillary free surfaces, is that in a large range of configurations liquid bridges between parallel plates are unstable with respect to small, even infinitesimal, tilting of one of the plates. Under a computationally based hypothesis of uniqueness of spherical bridges in a wedge, it is shown that the same discontinuous behavior prevails for all but very particular circumstances. The various liquid configurations, which form the basis for an experiment on board the Space Station {ital Mir}, are characterized and illustrated. {copyright} {ital 1998 American Institute of Physics.}

  7. Behavior of supercooled aqueous solutions stemming from hidden liquid-liquid transition in water

    NASA Astrophysics Data System (ADS)

    Biddle, John W.; Holten, Vincent; Anisimov, Mikhail A.

    2014-08-01

    A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid-liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid-liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two systems, H2O-NaCl and H2O-glycerol. We find the behavior of the heat capacity in supercooled aqueous solutions of NaCl, as reported by Archer and Carter [J. Phys. Chem. B 104, 8563 (2000)], to be consistent with the presence of the metastable liquid-liquid transition. We elucidate the non-conserved nature of the order parameter (extent of "reaction" between two alternative structures of water) and the consequences of its coupling with conserved properties (density and concentration). We also show how the shape of the critical line in a solution controls the difference in concentration of the coexisting liquid phases.

  8. Individual behavior and pairwise interactions between microswimmers in anisotropic liquid

    NASA Astrophysics Data System (ADS)

    Sokolov, Andrey; Zhou, Shuang; Lavrentovich, Oleg D.; Aranson, Igor S.

    2015-01-01

    A motile bacterium swims by generating flow in its surrounding liquid. Anisotropy of the suspending liquid significantly modifies the swimming dynamics and corresponding flow signatures of an individual bacterium and impacts collective behavior. We study the interactions between swimming bacteria in an anisotropic environment exemplified by lyotropic chromonic liquid crystal. Our analysis reveals a significant localization of the bacteria-induced flow along a line coaxial with the bacterial body, which is due to strong viscosity anisotropy of the liquid crystal. Despite the fact that the average viscosity of the liquid crystal is two to three orders of magnitude higher than the viscosity of pure water, the speed of bacteria in the liquid crystal is of the same order of magnitude as in water. We show that bacteria can transport a cargo (a fluorescent particle) along a predetermined trajectory defined by the direction of molecular orientation of the liquid crystal. We demonstrate that while the hydrodynamic interaction between flagella of two close-by bacteria is negligible, the observed convergence of the swimming speeds as well as flagella waves' phase velocities may occur due to viscoelastic interaction between the bacterial bodies.

  9. Solid-liquid critical behavior of water in nanopores.

    PubMed

    Mochizuki, Kenji; Koga, Kenichiro

    2015-07-01

    Nanoconfined liquid water can transform into low-dimensional ices whose crystalline structures are dissimilar to any bulk ices and whose melting point may significantly rise with reducing the pore size, as revealed by computer simulation and confirmed by experiment. One of the intriguing, and as yet unresolved, questions concerns the observation that the liquid water may transform into a low-dimensional ice either via a first-order phase change or without any discontinuity in thermodynamic and dynamic properties, which suggests the existence of solid-liquid critical points in this class of nanoconfined systems. Here we explore the phase behavior of a model of water in carbon nanotubes in the temperature-pressure-diameter space by molecular dynamics simulation and provide unambiguous evidence to support solid-liquid critical phenomena of nanoconfined water. Solid-liquid first-order phase boundaries are determined by tracing spontaneous phase separation at various temperatures. All of the boundaries eventually cease to exist at the critical points and there appear loci of response function maxima, or the Widom lines, extending to the supercritical region. The finite-size scaling analysis of the density distribution supports the presence of both first-order and continuous phase changes between solid and liquid. At around the Widom line, there are microscopic domains of two phases, and continuous solid-liquid phase changes occur in such a way that the domains of one phase grow and those of the other evanesce as the thermodynamic state departs from the Widom line.

  10. Phase behavior of cyclic siloxane-based liquid crystalline compounds

    SciTech Connect

    Gresham, K.D.; McHugh, C.M.; Bunning, T.J.; Crane, R.L.; Klei, H.E.; Samulski, E.T.

    1993-12-31

    The phase behavior of 24 cyclic siloxane liquid crystalline compounds are compared with respect to spacer length, composition, ring size, and mesogenic phase behavior. Penta- and tetramethylhydrocyclosiloxane rings were modified by biphenyl- and/or cholesterol-based molecules. A strong dependence of ring size on thermal behavior was observed for the homopolymers. 4-membered rings seem to inhibit the formation of liquid crystalline phases for biphenyl-based mesogens. Clearing temperatures for this series followed the melting temperatures of the unattached mesogens. Cholesterol-based compounds exhibited glass transition temperatures which increased substantially with spacer group length. A tendency to layer pack for the cholesterol compound was observed as smectic-A phases were formed.

  11. Active Mesogenic Droplets: Impact of Liquid Crystallinity and Collective Behavior

    NASA Astrophysics Data System (ADS)

    Bahr, Christian

    Droplets of common mesogenic compounds show a self-propelled motion when immersed in aqueous solutions containing ionic surfactants at concentrations well above the critical micelle concentration. After introducing some general properties of this type of artificial microswimmer, we focus on two topics: the influence of liquid crystallinity on the swimming behavior and the collective behavior of ensembles of a larger number of droplets. The mesogenic properties are not essential for the basic mechanism of self-propulsion, nevertheless they considerably influence the swimming behavior of the droplets. For instance, the shape of the trajectories strongly depends on whether the droplets are in the nematic or isotropic state. The droplet swimmers are also ideally suited for the study of collective behavior: Microfluidics enables the generation of large numbers of identical swimmers and we can tune their buoyancy. We report on the collective behavior in three-dimensional environments. Supported by the Deutsche Forschungsgemeinschaft (SPP 1726 ``Microswimmers'').

  12. Statistical mechanics of light elements at high pressure. VI - Liquid-state calculations with Thomas-Fermi-Dirac theory

    NASA Technical Reports Server (NTRS)

    Macfarlane, J. J.

    1984-01-01

    A model free energy is developed for hydrogen-helium mixtures based on solid-state Thomas-Fermi-Dirac calculations at pressures relevant to the interiors of giant planets. Using a model potential similar to that for a two-component plasma, effective charges for the nuclei (which are in general smaller than the actual charges because of screening effects) are parameterized, being constrained by calculations at a number of densities, compositions, and lattice structures. These model potentials are then used to compute the equilibrium properties of H-He fluids using a charged hard-sphere model. The results find critical temperatures of about 0 K, 500 K, and 1500 K, for pressures of 10, 100, and 1000 Mbar, respectively. These phase separation temperatures are considerably lower (approximately 6,000-10,000 K) than those found from calculations using free electron perturbation theory, and suggest that H-He solutions should be stable against phase separation in the metallic zones of Jupiter and Saturn.

  13. Corrosion behavior of surface treated steel in liquid sodium negative electrode of liquid metal battery

    NASA Astrophysics Data System (ADS)

    Lee, Jeonghyeon; Shin, Sang Hun; Lee, Jung Ki; Choi, Sungyeol; Kim, Ji Hyun

    2016-03-01

    While liquid metal batteries are attractive options for grid-scale energy storage applications as they have flexible siting capacities and small footprints, the compatibility between structural materials such as current collectors and negative electrode such as sodium is one of major issues for liquid metal batteries. Non-metallic elements such as carbon, oxygen, and nitrogen in the liquid sodium influence the material behaviors of the cell construction materials in the battery system. In this study, the compatibility of structural materials with sodium is investigated in high temperature liquid sodium, and electrochemical impedance spectroscopy (EIS) is used to monitor in-situ the corrosion behavior at the surface of materials in sodium. Chemical vapor deposition (CVD) coatings of SiC and Si3N4 are applied as protective barriers against dissolution and corrosion on the steel surface. The results show that CVD coating of Si compounds can delay corrosion of steel in high temperature liquid sodium comparing to the result of as-received specimens, while SiC coating is more durable than Si3N4 coating in high temperature liquid sodium.

  14. New phase boundary between magnetic and non-Fermi-liquid in Ce(Rh1-xRux)3B2, for 0⩽x⩽0.4

    NASA Astrophysics Data System (ADS)

    Bauer, E.; Hauser, R.; Galatanu, A.; Lindbaum, A.; Hilscher, G.; Sassik, H.; Kirchmayr, H.; Sereni, J. G.; Rogl, P.

    1998-06-01

    A study of the temperature-dependent magnetic susceptibility and electrical resistivity ρ(T) (0.5-300 K) on single-phase alloys (CaCu5 type), prepared by argon arc melting, reveals a magnetic phase transition with a nonmonotonous decrease of the ordering temperature from Tc=115 K for x=0 to Tc≈0 for x=0.40. A kink in the susceptibility at about 70 K indicates that ferromagnetism (at x<0.1) transforms to a complex magnetic order for 0.125⩽x⩽0.35. Above that concentration ρ(T)=ρ0+ATn changes from n≈2 to n≈1.5, a characteristic for non-Fermi-liquid behavior. Under pressure Tc stays almost constant for x=0.125 but dTc/dp grows with increasing Ru content. On the contrary, applied fields up to 12 T do not affect Tc. Low-temperature specific heat and ac susceptibility for x=0.40 confirm the absence of long-range magnetic order down to 0.5 K. For x=0.35 Cp/T=62 mJ/mol K at 1.5 K, a value which is three times larger than that of CeRh3B2.

  15. Bioinspired One-Dimensional Nano-Wrinkles Guide Liquid Behaviors at the Liquid-Solid Interfaces.

    PubMed

    Li, Jing; Sun, Quanmei; Chen, Long; Feng, Jiantao; Han, Dong

    2016-01-01

    Learning from nature concerning how nanostructured surfaces interact with liquids may provide insight into better understanding of inside living biological interfaces bearing these nanostructures and further development of innovative materials contacting water. Here we investigate the dynamic behaviour of water droplet interacting with one-dimensional nano-wrinkles of different size on polydimethylsiloxane (PDMS) surface. The structure design of the variationally one-dimensional nano-wrinkles is inspired by in vivo responding topographic changes in aortic intima, which was characterized with liquid-phase atomic force microscopy. We show here that increasing the amplitude of the wrinkles promotes the spreading and energy dissipation of liquid droplets on the wrinkled interfaces. This result suggests a possible bio-protection mechanism of blood vessels via its structural changes on the aortic intima against elevated flowing blood, and provides a basis for tuning interfacial nanostructure of optimal durability against wearing by the liquid behaviors. PMID:27398541

  16. Strongly correlated Fermi systems as a new state of matter

    NASA Astrophysics Data System (ADS)

    Shaginyan, V. R.; Msezane, A. Z.; Japaridze, G. S.; Popov, K. G.; Khodel, V. A.

    2016-10-01

    The aim of this review paper is to expose a new state of matter exhibited by strongly correlated Fermi systems represented by various heavy-fermion (HF) metals, two-dimensional liquids like 3He, compounds with quantum spin liquids, quasicrystals, and systems with one-dimensional quantum spin liquid. We name these various systems HF compounds, since they exhibit the behavior typical of HF metals. In HF compounds at zero temperature the unique phase transition, dubbed throughout as the fermion condensation quantum phase transition (FCQPT) can occur; this FCQPT creates flat bands which in turn lead to the specific state, known as the fermion condensate. Unlimited increase of the effective mass of quasiparticles signifies FCQPT; these quasiparticles determine the thermodynamic, transport and relaxation properties of HF compounds. Our discussion of numerous salient experimental data within the framework of FCQPT resolves the mystery of the new state of matter. Thus, FCQPT and the fermion condensation can be considered as the universal reason for the non-Fermi liquid behavior observed in various HF compounds. We show analytically and using arguments based completely on the experimental grounds that these systems exhibit universal scaling behavior of their thermodynamic, transport and relaxation properties. Therefore, the quantum physics of different HF compounds is universal, and emerges regardless of the microscopic structure of the compounds. This uniform behavior allows us to view it as the main characteristic of a new state of matter exhibited by HF compounds.

  17. Solid−liquid critical behavior of water in nanopores

    PubMed Central

    Mochizuki, Kenji; Koga, Kenichiro

    2015-01-01

    Nanoconfined liquid water can transform into low-dimensional ices whose crystalline structures are dissimilar to any bulk ices and whose melting point may significantly rise with reducing the pore size, as revealed by computer simulation and confirmed by experiment. One of the intriguing, and as yet unresolved, questions concerns the observation that the liquid water may transform into a low-dimensional ice either via a first-order phase change or without any discontinuity in thermodynamic and dynamic properties, which suggests the existence of solid−liquid critical points in this class of nanoconfined systems. Here we explore the phase behavior of a model of water in carbon nanotubes in the temperature−pressure−diameter space by molecular dynamics simulation and provide unambiguous evidence to support solid−liquid critical phenomena of nanoconfined water. Solid−liquid first-order phase boundaries are determined by tracing spontaneous phase separation at various temperatures. All of the boundaries eventually cease to exist at the critical points and there appear loci of response function maxima, or the Widom lines, extending to the supercritical region. The finite-size scaling analysis of the density distribution supports the presence of both first-order and continuous phase changes between solid and liquid. At around the Widom line, there are microscopic domains of two phases, and continuous solid−liquid phase changes occur in such a way that the domains of one phase grow and those of the other evanesce as the thermodynamic state departs from the Widom line. PMID:26100904

  18. Enrico Fermi

    NASA Astrophysics Data System (ADS)

    Yang, Chen Ning

    2013-05-01

    Enrico Fermi was, of all the great physicists of the 20th century, among the most respected and admired. He was respected and admired because of his contributions to both theoretical and experimental physics, because of his leadership in discovering for mankind a powerful new source of energy, and above all, because of his personal character. He was always reliable and trustworthy. He had both of his feet on the ground all the time. He had great strength, but never threw his weight around. He did not play to the gallery. He did not practise one-up-manship. He exemplified, I always believe, the perfect Confucian gentleman...

  19. Liquid-vapor critical behavior in silica aerogel

    NASA Astrophysics Data System (ADS)

    Herman, Tobias Kent

    Fluids in porous media provide a testing ground for the effects of disorder and confinement on phase transitions and critical phenomena. Specifically, highly porous silica aerogel with its tenuous solid structure has allowed low temperature physicists to probe the effect of dilute fixed impurities on both the 4He superfluid transition and the 3He superfluid transition. Both systems have yielded exciting results and work is ongoing, especially on 3He in aerogel. This thesis explores the effect of aerogel on another transition---the liquid-vapor transition near the liquid-vapor critical point. In dense porous media, the liquid-vapor transition is usually described as capillary condensation---a process which assigns surface tension a primary role in determining the thermodynamic state of the system. However, aerogels are often so diffuse (less than 5% silica by volume---the rest is open space) that it becomes difficult to speak of pore size and meniscus shape as one would in a denser porous medium. As one approaches the liquid-vapor critical point, thermal fluctuations within the fluid grow until they exceed the scale of the aerogel strands and pores themselves. In this regime one cannot expect surface tension to control the thermodynamics of the system---it is instead in a regime where thermal fluctuations may govern its behavior. In the past there were even suggestions that the addition of aerogel might shift the character of the transition into another universality class. The following chapters present data collected on helium and neon in aerogel near their respective liquid-vapor critical points. While the behavior of the fluid at low temperatures is consistent with the pictures provided by capillary condensation, closer to the critical point they are incompatible and remain somewhat unexplained. Evidence for a shift in universality class was not found---in fact there was very little evidence for a macroscopic equilibrium transition of any type.

  20. Analysis of feeding behavior of Drosophila larvae on liquid food.

    PubMed

    Shen, Ping

    2012-05-01

    The food responses of Drosophila larvae offer an excellent opportunity to study the genetic and neural regulation of feeding behavior. Compared with fed larvae, hungry larvae are more likely to display aggressive foraging, rapid food intake, compensatory feeding, and stress-resistant food procurement. Behavioral assays have been developed to quantitatively assess particular aspects of the hunger-driven food response. In combination, these assays help define the specific role of signaling molecules or neurons in the regulation of feeding behavior in foraging larvae. This protocol describes the analysis of larvae feeding on liquid food. The test is designed for quantitative assessment of the food ingestion rate of individual larvae under different energy states. It provides a simple and reliable way to measure the graded modification of the baseline feeding rate of larvae as food deprivation is prolonged. The test is applicable to routine functional testing and larger-scale screening of genetic mutations and biologics that might affect food consumption.

  1. Importance of Fermi energy for understanding the intermixing behavior at the LaAlO{sub 3}/SrTiO{sub 3} heterointerface

    SciTech Connect

    Yamamoto, Takashi; Mizoguchi, Teruyasu

    2014-11-17

    We investigated the migration energy and vacancy formation energy of La and Sr ions at a LaAlO{sub 3}/SrTiO{sub 3} heterointerface using first-principles calculations. Our study reveal that the migration energies at the p-type interface are lower than those at the n-type interface, and the formation energies of Sr and La vacancies are relatively high when we assume a reduction atmosphere and insulator conditions. To explain the experimental evidence that intermixing is preferentially taking place at the n-type interface, considering the Fermi energy is critical. We find that the presence of electron carriers plays an important role in the intermixing behaviors at the LaAlO{sub 3}/SrTiO{sub 3} heterointerface.

  2. Ultra-fast single-file transport of a simple liquid beyond the collective behavior zone.

    PubMed

    Su, Jiaye; Yang, Keda; Huang, Decai

    2016-07-27

    We use molecular dynamics simulations to analyze the single-file transport behavior of a simple liquid through a narrow membrane channel. With the decrease of the liquid-channel interaction, the liquid flow exhibits a remarkable maximum behavior owing to the competition of liquid-liquid and liquid-channel interactions. Surprisingly, this maximum flow is coupled to a sudden reduce of the liquid occupancy, where the liquid particle is moving through the channel alone at nearly constant velocity, rather than in a collective motion mode. Further investigation on the encountered energy barrier suggests that this maximum flow should be induced by particles having large instant velocities (or thermal fluctuation) that overcome the liquid-liquid and liquid-channel interaction barriers. Further decreasing the liquid-channel interaction leads to the decrease and ultimate stabilization of the liquid flow, since the energy barrier will increase and becomes steady. These results suggest that the breakdown of collective behavior can be a new rule for achieving fast single-file transportation, especially for simple or nonpolar liquids with relatively weak liquid-liquid interactions, and is thus helpful for the design of high flux nanofluidic devices.

  3. Heavy fermions. Unconventional Fermi surface in an insulating state.

    PubMed

    Tan, B S; Hsu, Y-T; Zeng, B; Hatnean, M Ciomaga; Harrison, N; Zhu, Z; Hartstein, M; Kiourlappou, M; Srivastava, A; Johannes, M D; Murphy, T P; Park, J-H; Balicas, L; Lonzarich, G G; Balakrishnan, G; Sebastian, Suchitra E

    2015-07-17

    Insulators occur in more than one guise; a recent finding was a class of topological insulators, which host a conducting surface juxtaposed with an insulating bulk. Here, we report the observation of an unusual insulating state with an electrically insulating bulk that simultaneously yields bulk quantum oscillations with characteristics of an unconventional Fermi liquid. We present quantum oscillation measurements of magnetic torque in high-purity single crystals of the Kondo insulator SmB6, which reveal quantum oscillation frequencies characteristic of a large three-dimensional conduction electron Fermi surface similar to the metallic rare earth hexaborides such as PrB6 and LaB6. The quantum oscillation amplitude strongly increases at low temperatures, appearing strikingly at variance with conventional metallic behavior.

  4. Electrochemical behavior of coals, H-coal liquids & FE++ ion

    NASA Astrophysics Data System (ADS)

    Baldwin, R. P.; Jones, K. F.; Joseph, J. T.; Wong, J. L.

    1981-02-01

    Recently, Coughlin et al. have shown that a redox couple involving the oxidation of coal and the reduction of H+ at the cathode and primarily CO2 at the anode. We have examined the electrochemical behavior of various Kentucky coals and H-Coal liquids at platinum electrodes under voltammetric and electrolytic conditions, and found that the reported electrochemical process is not a general one, and that Fe++ may yield a similar phenomenon. Thus, agueous 0.1M LiClO4 slurries of most coals were found to yield characteristic voltammograms containing anodic waves starting at +0.4 volts vs. SCE and extending throughout the positive potential range. The resulting oxidation currents were proportional in magnitude to the coal concentration employed. Upon filtration, the bulk of the electro-activity of the coal slurry was found to be retained in the filtrate while the remaining coal residue showed drastically diminished currents upon formation of a new slurry. Atomic absorption analysis of the filtrate revealed iron concentrations in the parts-per-thousand range. It was determined that the half-wave potential of Fe2+ occurred at +0.45 volts under the conditions employed. Also, acetonitrile coal slurries and acetonitrile solutions of H-Coal liquids exhibited no larger electrolysis currents than were obtained with blank solutions.

  5. Amphiphilic behavior of two phosphonium based ionic liquids.

    PubMed

    Mukherjee, Indrajyoti; Mukherjee, Suvasree; Naskar, Bappaditya; Ghosh, Soumen; Moulik, Satya P

    2013-04-01

    Solution and surface chemical behavior of two phosphonium based ionic liquids triisobutyl (methyl) phosphonium tosylate (IL-1) and trihexyl (tetradecyl) phosphonium bis 2,4,4-(trimethylpentyl)phosphinate (IL-2) have been studied. The polar IL-1 is surface active and water soluble, whereas the weakly polar IL-2 is more surface active with very low aqueous solubility. IL-1 does not form micelles but affects the micellization properties of ionic, nonionic, and zwitterionic surfactants more strongly than conventional electrolytes. IL-2 itself forms micelles and mixed micelles with Triton X-100 (TX-100) in aqueous solution. It also forms Langmuir monolayers of liquid expanded type, at the air/water interface. IL-1 can replace water in forming microemulsions with the oil isopropylmyristate (IPM), stabilized by IL-2 (surfactant)+isopropanol (IP as a co-surfactant) like the IL-1/IPM/(IL-2+IP) system. It produces a large monophasic zone in the pseudoternary phase diagram. The thermodynamics of formation of the microemulsions of IL-1 in oil (IPM) have been examined. The dimensions and the polydispersity of the dispersed nano-droplets in the microemulsions have been determined by DLS. The thermal stability of the microemulsion forming systems has also been studied. ILs studied against Sarcoma-180 cell lines have evidenced proficient anti-cancer activity of IL-1 and moderate activity of IL-2. PMID:23317771

  6. Critical behavior of liquid {sup 4}He at negative pressures

    SciTech Connect

    Campbell, C.E.; Folk, R.; Krotscheck, E.

    1996-10-01

    The authors examine the equation of state of liquid {sup 4}He at negative pressures close to the spinodal density {rho}{sub s} where the hydrodynamic speed of sound vanishes. The non-analytic behavior of the equation of state and the speed of sound in the vicinity of the spinodal density are calculated in two and in three dimensions; they find for the speed of sound the non-analytic behavior mc{sub s}{sup 2} {approximately} ({rho}-{rho}{sub s}){sup 2/5} in three dimensions and mc{sub s}{sup 2} {approximately} [({rho}-{rho}{sub s})/{vert_bar}ln({rho}-{rho}{sub s}){vert_bar}]{sup 1/2} in two dimensions. The authors then examine the low density regime numerically, using a semianalytic microscopic theory. It is found that non-analytic exponents are visible only in a negligible density regime around the spinodal point. Estimates for the spinodal densities, and the range of critical fluctations are provided.

  7. Relaxation dynamics in the Fermi-Hubbard model

    NASA Astrophysics Data System (ADS)

    Xu, Wenchao; McGehee, William; Morong, William; Demarco, Brian; DeMarco Group Team

    2015-05-01

    We report measurements of spin-excitation relaxation rates for ultracold 40 K atoms trapped in an optical lattice in the metallic regime of the Hubbard model. A spin-polarized gas is prepared in a well-defined state in a cubic optical lattice. Via a quasimomentum-selective Raman pulse, atoms are transferred into another spin state with non-zero center-of-mass momentum. The timescale for relaxation of this excitation is measured as the temperature and lattice potential depth are varied. Non-Fermi liquid behavior is revealed in both the temperature and interaction-strength dependence.

  8. Fermi Pulsar Analysis

    NASA Video Gallery

    This animation illustrates how analysis of Fermi data reveals new pulsars. Fermi's LAT records the precise arrival time and approximate direction of the gamma rays it detects, but to identify a pul...

  9. Nanostructuration Effect on the Thermal Behavior of Ionic Liquids.

    PubMed

    Rodrigues, Ana S M C; Santos, Luís M N B F

    2016-05-18

    This work shows how the nanostructuration of ionic liquids (ILs) governs the glass and melting transitions of the bistriflimide imidazolium-based [Cn C1 im][NTf2 ] and [Cn Cn im][NTf2 ] series, which highlights the trend shift that occurs at the critical alkyl size (CAS) of n=6. An initial increase in the glass temperature (Tg ) with an increase in the alkyl side chain was observed due to the intensification of the dispersive interactions (van der Waals). Above the CAS, the -CH2 - increment has the same effect in both glass and liquid states, which leads to a plateau in the glass transition after nanostructuration. The melting temperature (Tm ) of the [Cn C1 im][NTf2 ] and [Cn Cn im][NTf2 ] series presents a V-shaped profile. For the short-alkyl ILs, the -CH2 - increment affects the electrostatic ion pair interactions, which leads to an increase in the conformational entropy. The -CH2 - increment disturbs the packing ability of the ILs and leads to a higher entropy value (ΔslSm○ ) and consequently a decrease in Tm . Above the CAS, the -CH2 - contribution to the melting temperature becomes more regular, as a consequence of the nanostructuration of the IL into polar and nonpolar domains. The dependence of the alkyl chain on the temperature, enthalpy, and entropy of melting in the ILs above the CAS is very similar to the one observed for the alkane series, which highlights the importance of the nonpolar alkyl domains on the ILs thermal behavior.

  10. Self-Associating Behavior of Acetone in Liquid Krypton.

    PubMed

    De Beuckeleer, Liene I; Herrebout, Wouter A

    2016-02-18

    Acetone molecules are inclined to self-associate through dipole-dipole interactions because of their large dipole moment. Infrared spectroscopy of compounds dissolved in liquid noble gases supported by high level ab initio calculations allows investigating the self-associating behavior and determining the thermodynamical properties. In this study, infrared spectra of various concentrations of acetone dissolved in liquid krypton are recorded at constant temperature. Overlapping monomer and dimer spectra are separated by analyzing the obtained data sets with numerical methods based on least-squares fitting. Although acetone is known to self-associate, only a few spectral features have been presented in literature before. In this study, the application of new numerical approaches succeeds in resolving overlapping spectra and allows observing isolated acetone dimer absorption bands for the complete mid infrared spectrum. By use of data sets of spectra recorded at temperatures between 134 and 142 K, the experimental standard dimerization enthalpy was determined to be -10.8 kJ mol(-1). MP2/aug-cc-pVDZ calculations predicted a stacked and planar dimer geometry of which the stacked geometry is more stable. Combining MP2 energies and single point corrections involving CCSD(T) calculations and complete basis set extrapolations based on the MP2/aug-cc-pVDZ equilibrium geometry lead to complexation energy of -28.4 kJ mol(-1) for the stacked geometry and -15.1 kJ mol(-1) for the planar geometry. The corresponding values for the complexation enthalpies in solution, obtained by combining these values with corrections for thermal and solvent influences are -13.7 and -5.8 kJ mol(-1).

  11. Self-Associating Behavior of Acetone in Liquid Krypton.

    PubMed

    De Beuckeleer, Liene I; Herrebout, Wouter A

    2016-02-18

    Acetone molecules are inclined to self-associate through dipole-dipole interactions because of their large dipole moment. Infrared spectroscopy of compounds dissolved in liquid noble gases supported by high level ab initio calculations allows investigating the self-associating behavior and determining the thermodynamical properties. In this study, infrared spectra of various concentrations of acetone dissolved in liquid krypton are recorded at constant temperature. Overlapping monomer and dimer spectra are separated by analyzing the obtained data sets with numerical methods based on least-squares fitting. Although acetone is known to self-associate, only a few spectral features have been presented in literature before. In this study, the application of new numerical approaches succeeds in resolving overlapping spectra and allows observing isolated acetone dimer absorption bands for the complete mid infrared spectrum. By use of data sets of spectra recorded at temperatures between 134 and 142 K, the experimental standard dimerization enthalpy was determined to be -10.8 kJ mol(-1). MP2/aug-cc-pVDZ calculations predicted a stacked and planar dimer geometry of which the stacked geometry is more stable. Combining MP2 energies and single point corrections involving CCSD(T) calculations and complete basis set extrapolations based on the MP2/aug-cc-pVDZ equilibrium geometry lead to complexation energy of -28.4 kJ mol(-1) for the stacked geometry and -15.1 kJ mol(-1) for the planar geometry. The corresponding values for the complexation enthalpies in solution, obtained by combining these values with corrections for thermal and solvent influences are -13.7 and -5.8 kJ mol(-1). PMID:26805773

  12. Magnetic short-range correlations and quantum critical scattering in the non-Fermi liquid regime of URu{sub 2-x}Re{sub x}Si{sub 2} (x = 0.2-0.6).

    SciTech Connect

    Krishnamurthy, V. V.; Adroja, D. T.; Butch, N. P.; Osborn, R.; Sinha, S. K.; Robertson, J. L.; Aronson, M. C.; Nagler, S. E.; Maple, M. B.; ORNL; Rutherford Appleton Lab.; Univ. California at San Diego; Univ. Michigan

    2008-01-01

    The spin dynamics of uranium ions in the non-Fermi liquid compounds URu{sub 2-x}Re{sub x}Si{sub 2}, for x=0.2 to 0.6, have been investigated using inelastic neutron scattering. The wave vector (q) dependence of the magnetic scattering provides evidence of short-range antiferromagnetic correlations at low temperatures for x=0.2,0.25, but the scattering is nearly q independent at x=0.35,0.6. The magnetic response, {bar S}({omega}), obtained from the q-independent part of neutron scattering, varies as {omega}{sup -{alpha}} with a composition-dependent exponent {alpha} = 0.2-0.5. The dynamic magnetic susceptibility {chi}{double_prime}(q,{omega}) of the q-independent part exhibits {omega}/T scaling for the energy transfer {bar h}{omega} between 3.5 and 17 meV in the temperature (T) range of 5-300 K at all the compositions. This scaling, which indicates local quantum criticality, breaks down in the q range, 0.6-1.1 {angstrom}{sup -1} at x = 0.2 and 0.25, that is dominated by short-range antiferromagnetic correlations. The appearance of power laws in the magnetic response measured by inelastic neutron scattering over a wide Re doping region indicates a disorder driven non-Fermi liquid mechanism for the low-temperature physical properties in these compounds.

  13. The self-associating behavior of pyrrole in liquid xenon

    NASA Astrophysics Data System (ADS)

    De Beuckeleer, Liene I.; Herrebout, Wouter A.

    2016-03-01

    The self-associating behavior of pyrrole in liquid xenon was investigated by analyzing a data set of 185-113 infrared spectra obtained for different concentrations recorded at a constant temperature of 203 K. Analysis of the data using a recently developed least-squares approach allows the vibrational spectra of the monomer and of the different oligomers to be isolated. Apart from the monomer transitions, intense absorption bands originating from pyrrole trimers are observed in almost every spectral region including regions for which no data have yet been reported. Apart from these bands, weak features proving the presence of pyrrole dimer and pyrrole tetramer in the solutions are also reported. The weak character of the dimer bands observed and the low concentrations of these species deduced are explained by the fact that the cryosolutions studied are in chemical equilibrium and by the fact that due to strong cooperative effect present in the trimer, the complexation equilibria are strongly shifted towards the latter species, thereby strongly reducing the equilibrium concentrations of dimer and tetramer.

  14. Anomalous effect of flow rate on the electrochemical behavior at a liquid|liquid interface under microfluidic conditions.

    PubMed

    Kaluza, Dawid; Adamiak, Wojciech; Kalwarczyk, Tomasz; Sozanski, Krzysztof; Opallo, Marcin; Jönsson-Niedziolka, Martin

    2013-12-23

    We have investigated the oxidation of ferrocene at a flowing organic solvent|aqueous electrolyte|solid electrode junction in a microfluidic setup using cyclic voltammetry and fluorescent laser scanning confocal microscopy. At low flow rates the oxidation current decreases with increasing flow, contrary to the Levich equation, but at higher flow rates the current increases linearly with the cube root of the flow rate. This behavior is explained using a simple model postulating a smallest effective width of the three-phase junction, which after fitting to the data comes to be ca. 20 μm. The fluorescence microscopy reveals mixing of the two phases close to the PDMS cover, but the liquid|liquid junction is stable close to the glass support. This study shows the importance of the solid|liquid|liquid junctions for the behavior of multiphase systems under microfluidic conditions.

  15. Unveiling Unidentified Fermi Sources

    NASA Astrophysics Data System (ADS)

    Zhang, Lizhong; South Pole Telescope

    2016-01-01

    The Fermi γ-ray Space Telescope (Fermi) has surveyed the entire sky at the highest-energy band of the electromagnetic spectrum. The majority of Fermi sources have counterpart identifications from multi-wavelength large-area surveys, particularly in the radio and x-ray bands. However, around 35% of Fermi sources remain unidentified, a problem exasperated by the low resolution of the telescope. Understanding the nature of unidentified Fermi sources is one of the most pressing problems in γ-ray astronomy. The South Pole Telescope (SPT) has completed a survey covering a 2500 square degrees of the southern extragalactic sky with arcminute resolution at millimeter wavelengths. The mm wavelength is the most efficient means to identify blazars and unidentified Fermi sources. Our analysis shows that the SPT point source catalog provides candidate associations for 40% of the unidentified Fermi sources, showing them to be flat-spectrum radio quasars which are extraordinarily bright at millimeter (mm) wavelengths.

  16. The Influence of Disorder on Thermotropic Nematic Liquid Crystals Phase Behavior

    PubMed Central

    Popa-Nita, Vlad; Gerlič, Ivan; Kralj, Samo

    2009-01-01

    We review the theoretical research on the influence of disorder on structure and phase behavior of condensed matter system exhibiting continuous symmetry breaking focusing on liquid crystal phase transitions. We discuss the main properties of liquid crystals as adequate systems in which several open questions with respect to the impact of disorder on universal phase and structural behavior could be explored. Main advantages of liquid crystalline materials and different experimental realizations of random field-type disorder imposed on liquid crystal phases are described. PMID:19865529

  17. Shear Flow Induced Transition from Liquid-Crystalline to Polymer Behavior in Side-Chain Liquid Crystal Polymers

    SciTech Connect

    Noirez, L.; Lapp, A.

    1997-01-01

    We determine the structure and conformation of side-chain liquid-crystalline polymers subjected to shear flow in the vicinity of the smectic phase by neutron scattering on the velocity gradient plane. Below the nematic-smectic transition we observe a typical liquid-crystal behavior; the smectic layers slide, leading to a main-chain elongation parallel to the velocity direction. In contrast,a shear applied above the transition induces a tilted main-chain conformation which is typical for polymer behavior. {copyright} {ital 1996} {ital The American Physical Society}

  18. Dynamic Behavior of Liquids in Annuli Entrained with Gas

    NASA Astrophysics Data System (ADS)

    Gaponenko, Yuri; Mialdun, Alexander; Shevtsova, Valentina

    Heat/mass transfer on the moving gas-liquid interface is an important subject directly related to many industrial applications from crystal growth to cooling of electronic devices. In the case of non-uniform temperature in liquid the overall scenario depends on thermo-capillary convection in liquid which is affected by moving gas along the interface. Space experiment JEREMI (Japanese European Research Experiment on Marangoni Instabilities) is devoted to the study of the threshold of hydrothermal instabilities in two-phase systems. The present study is one of the first steps on the way of the experiment preparation. We report the results of numerical and experimental study of two-phase flows in annulus. The internal column consists of solid supports at the bottom and top, while the central part is a liquid zone filled with viscous liquid and kept in its position by surface tension. Gas enters into the annular duct and entrains initially quiescent liquid. The flow field in liquid is investigated for increasing gas velocity from zero up to 2m/s (correspondingly, Reynolds number in gas varies as 0¡Re¡600). The flow field is analyzed for the different viscosity ratios between liquid and gas. An excellent agreement between computed results and experimental data demonstrates that the developed experimental technique and numerical code are capable to capture the main characteristics of the phenomenon studied.

  19. Collisional Properties of a Polarized Fermi Gas with Resonant Interactions

    SciTech Connect

    Bruun, G. M.; Recati, A.; Stringari, S.; Pethick, C. J.; Smith, H.

    2008-06-20

    Highly polarized mixtures of atomic Fermi gases constitute a novel Fermi liquid. We demonstrate how information on thermodynamic properties may be used to calculate quasiparticle scattering amplitudes even when the interaction is resonant and apply the results to evaluate the damping of the spin dipole mode. We estimate that under current experimental conditions the mode would be intermediate between the hydrodynamic and collisionless limits.

  20. Strong Coupling Effects on the Specific Heat of an Ultracold Fermi Gas in the Unitarity Limit

    NASA Astrophysics Data System (ADS)

    van Wyk, P.; Tajima, H.; Hanai, R.; Ohashi, Y.

    2016-05-01

    We investigate strong-coupling corrections to the specific heat C_V in the normal state of an ultracold Fermi gas in the BCS-BEC crossover region. A recent experiment on a ^6Li unitary Fermi gas (Ku et. al. in Science 335:563 2012) shows that C_V is remarkably amplified near the superfluid phase transition temperature T_c, being similar to the well-known λ -structure observed in liquid ^4He. Including pairing fluctuations within the framework of the strong-coupling theory developed by Nozières and Schmitt-Rink, we show that strong pairing fluctuations are sufficient to explain the anomalous behavior of C_V observed in a ^6Li unitary Fermi gas near T_c. We also show that there is no contribution from stable preformed Cooper pairs to C_V at the unitarity. This indicates that the origin of the observed anomaly is fundamentally different from the case of liquid 4He, where stable ^4He Bose atoms induce the λ -structure in C_V near the superfluid instability. Instead, the origin is the suppression of the entropy S, near T_c, due to the increase of metastable preformed Cooper pairs. Our results indicate that the specific heat is a useful quantity to study the effects of pairing fluctuations on the thermodynamic properties of an ultracold Fermi gas in the BCS-BEC crossover region.

  1. Supporting implementation of evidence-based behavioral interventions: the role of data liquidity in facilitating translational behavioral medicine.

    PubMed

    Abernethy, Amy P; Wheeler, Jane L; Courtney, Paul K; Keefe, Francis J

    2011-03-01

    The advancement of translational behavioral medicine will require that we discover new methods of managing large volumes of data from disparate sources such as disease surveillance systems, public health systems, and health information systems containing patient-centered data informed by behavioral and social sciences. The term "liquidity," when applied to data, refers to its availability and free flow throughout human/computer interactions. In seeking to achieve liquidity, the focus is not on creating a single, comprehensive database or set of coordinated datasets, nor is it solely on developing the electronic health record as the "one-stop shopping" source of health-related data. Rather, attention is on ensuring the availability of secure data through the various methods of collecting and storing data currently existent or under development-so that these components of the health information infrastructure together support a liquid data system. The value of accessible, interoperable, high-volume, reliable, secure, and contextually appropriate data is becoming apparent in many areas of the healthcare system, and health information liquidity is currently viewed as an important component of a patient-centered healthcare system. The translation from research interventions to behavioral and psychosocial indicators challenges the designers of healthcare systems to include this new set of data in the correct context. With the intention of advancing translational behavioral medicine at the local level, "on the ground" in the clinical office and research institution, this commentary discusses data liquidity from the patient's and clinician's perspective, requirements for a liquid healthcare data system, and the ways in which data liquidity can support translational behavioral medicine.

  2. SOLID-STATE PHYSICS. Scalable T² resistivity in a small single-component Fermi surface.

    PubMed

    Lin, Xiao; Fauqué, Benoît; Behnia, Kamran

    2015-08-28

    Scattering among electrons generates a distinct contribution to electrical resistivity that follows a quadratic temperature (T) dependence. In strongly correlated electron systems, the prefactor A of this T(2) resistivity scales with the magnitude of the electronic specific heat, γ. Here we show that one can change the magnitude of A by four orders of magnitude in metallic strontium titanate (SrTiO3) by tuning the concentration of the carriers and, consequently, the Fermi energy. The T(2) behavior persists in the single-band dilute limit despite the absence of two known mechanisms for T(2) behavior: distinct electron reservoirs and Umklapp processes. The results highlight the absence of a microscopic theory for momentum decay through electron-electron scattering in various Fermi liquids.

  3. Controlled Shape Memory Behavior of a Smectic Main-Chain Liquid Crystalline Elastomer

    SciTech Connect

    Li, Yuzhan; Pruitt, Cole; Rios, Orlando; Wei, Liqing; Rock, Mitch; Keum, Jong K.; McDonald, Armando G.; Kessler, Michael R.

    2015-04-10

    Here, we describe how a smectic main-chain liquid crystalline elastomer (LCE), with controlled shape memory behavior, is synthesized by polymerizing a biphenyl-based epoxy monomer with an aliphatic carboxylic acid curing agent. Microstructures of the LCEs, including their liquid crystallinity and cross-linking density, are modified by adjusting the stoichiometric ratio of the reactants to tailor the thermomechanical properties and shape memory behavior of the material. Thermal and liquid crystalline properties of the LCEs, characterized using differential scanning calorimetry and dynamic mechanical analysis, and structural analysis, performed using small-angle and wide-angle X-ray scattering, show that liquid crystallinity, cross-linking density, and network rigidity are strongly affected by the stoichiometry of the curing reaction. With appropriate structural modifications it is possible to tune the thermal, dynamic mechanical, and thermomechanical properties as well as the shape memory and thermal degradation behavior of LCEs.

  4. Controlled Shape Memory Behavior of a Smectic Main-Chain Liquid Crystalline Elastomer

    DOE PAGES

    Li, Yuzhan; Pruitt, Cole; Rios, Orlando; Wei, Liqing; Rock, Mitch; Keum, Jong K.; McDonald, Armando G.; Kessler, Michael R.

    2015-04-10

    Here, we describe how a smectic main-chain liquid crystalline elastomer (LCE), with controlled shape memory behavior, is synthesized by polymerizing a biphenyl-based epoxy monomer with an aliphatic carboxylic acid curing agent. Microstructures of the LCEs, including their liquid crystallinity and cross-linking density, are modified by adjusting the stoichiometric ratio of the reactants to tailor the thermomechanical properties and shape memory behavior of the material. Thermal and liquid crystalline properties of the LCEs, characterized using differential scanning calorimetry and dynamic mechanical analysis, and structural analysis, performed using small-angle and wide-angle X-ray scattering, show that liquid crystallinity, cross-linking density, and network rigiditymore » are strongly affected by the stoichiometry of the curing reaction. With appropriate structural modifications it is possible to tune the thermal, dynamic mechanical, and thermomechanical properties as well as the shape memory and thermal degradation behavior of LCEs.« less

  5. Study on Orbital Liquid Transport and Interface Behavior in Vane Tank

    NASA Astrophysics Data System (ADS)

    Kang, Qi; Rui, Wei

    2016-07-01

    Liquid propellant tank is used to supply gas free liquid for spacecraft as an important part of propulsion system. The liquid behavior dominated by surface tension in microgravity is obviously different with that on the ground, which put forward a new challenge to the liquid transport and relocation. The experiments which are investigated at drop tower in National Microgravity Lab have concentrated on liquid relocation following thruster firing. Considered that the liquid located at the bottom in the direction of the acceleration vector, a sphere scale vane tank is used to study the liquid-gas interface behaviors with different acceleration vector and different filling independently and we obtain a series of stable equilibrium interface and relocation time. We find that there is an obvious sedimentation in the direction of acceleration vector when fill rate greater than 2% fill. Suggestions have been put forward that outer vanes transferring liquid to the outlet should be fixed and small holes should be dogged at the vane close to the center post to improve the liquid flow between different vanes when B0 is greater than 2.5. The research about liquid transport alone ribbon vanes is simulated though software Flow3D. The simulation process is verified by comparing the liquid lip and vapor-liquid interface obtained from drop tower experiment and simulation result when fill rate is 15%. Then the influence of fill rate, numbers of vanes and the gap between vane and wall is studied through the same simulate process. Vanes' configurations are also changed to study the effect on the lip and liquid volume below some section. Some suggestions are put forward for the design of vanes.

  6. Phase behavior and dynamics of a cholesteric liquid crystal

    SciTech Connect

    Roy, D.; Fragiadakis, D.; Roland, C. M.; Dabrowski, R.; Dziaduszek, J.; Urban, S.

    2014-02-21

    The synthesis, equation of state, phase diagram, and dielectric relaxation properties are reported for a new liquid crystal, 4{sup ′}-butyl-4-(2-methylbutoxy)azoxybenzene (4ABO5*), which exhibits a cholesteric phase at ambient temperature. The steepness of the intermolecular potential was characterized from the thermodynamic potential parameter, Γ = 4.3 ± 0.1 and the dynamic scaling exponent, γ = 3.5 ± 0.2. The difference between them is similar to that seen previously for nematic and smectic liquid crystals, with the near equivalence of Γ and γ consistent with the near constancy of the relaxation time of 4ABO5* at the cholesteric to isotropic phase transition (i.e., the clearing line). Thus, chirality does not cause deviations from the general relationship between thermodynamics and dynamics in the ordered phase of liquid crystals. The ionic conductivity of 4ABO5* shows strong coupling to the reorientational dynamics.

  7. Optical properties and Fermi-surface nesting in superconducting oxides

    SciTech Connect

    Ruvalds, J.; Virosztek, A. )

    1991-03-01

    Fermi-surface nesting is found to modify the electron-electron scattering and therefore yields an unusual variation of the optical reflectivity. At long wavelengths a Drude form of the dielectric function is derived with a relaxation rate for a nested Fermi liquid (NFL) that is linear in frequency for {omega}{gt}{ital T}. The corresponding Drude mass is also frequency and temperature dependent. Remarkably good fits to the reflectivity of YBa{sub 2}Cu{sub 3}O{sub 7}, Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}, and La{sub 2{minus}{ital x}}Sr{sub {ital x}}CuO{sub 4} are achieved using an on-site Coulomb interaction of intermediate strength. The static limit for the NFL conductivity is compatible with the temperature-dependent resistivity of the high-temperature superconductors. Self-energy and vertex corrections yield a long-wavelength susceptibility that is much weaker and different in structure from the response at the nesting wave vector {bold Q}, and the distinctions are relevant to the Raman spectrum. In cases of imperfect nesting, a crossover to conventional Fermi-liquid behavior is possible at a temperature {ital T}{sup *} determined by the quasiparticle orbits. Predictions for the optical response as a function of chemical composition are discussed, with attention to the anomalous resistivity of Nd{sub 2{minus}{ital x}}Ce{sub {ital x}}CuO{sub 4}.

  8. Precise prediction of optical responses of liquid-crystal display products using a behavioral model of liquid crystal

    NASA Astrophysics Data System (ADS)

    Park, Chansoo; Cho, Youngmin; Kim, Jong-Man; Kim, Jongbin; Lee, Seung-Woo

    2012-01-01

    We propose a precise circuit model to estimate transient optical responses of an active-matrix liquid crystal display (AMLCD). Liquid crystal (LC) molecules in the pixel is behaviorally modeled by using the first-order system that is described by Verilog-A. Capacitance-voltage (C-V) characteristics of a pixel determine the accuracy of the dynamic responses. Measuring C-V characteristics is impossible because pixels are driven by switching transistors in the AMLCD. We propose a method to obtain the C-V data from natural optical responses. Estimated optical responses based on the C-V data extracted by our proposal show more accurate results than those based on C-V data obtained by using transmittance-voltage data. It is demonstrated that our behavioral model enables us to predict very accurate transient responses, which makes it possible to design LCD products with lower costs.

  9. Dynamic behaviors of dual frequency liquid crystals in bistable chiral tilted-homeotropic nematic liquid crystal cell

    NASA Astrophysics Data System (ADS)

    Hsu, Jy-Shan; Liang, Bau-Jy; Chen, Shu-Hsia

    2006-07-01

    The switching behaviors of dual frequency liquid crystals (DFLC) in a bistable chiral tilted-homeotropic nematic (BHN) LC cell are simulated and compared with the observed results. This cell can be switched between tilted-homeotropic state and twisted state under the applied voltage as low as 5V. The reason for the low switching voltage is attributed to the dielectric anisotropy character of DFLC. The analysis also shows that the switching wave form accelerates the switching behaviors of the directors which results in faster response in BHN LC cell.

  10. A Comprehensive Study on Lyotropic Liquid-Crystalline Behavior of an Amphiphile in 20 Kinds of Amino Acid Ionic Liquids.

    PubMed

    Fujimura, Kanae; Ichikawa, Takahiro; Yoshio, Masafumi; Kato, Takashi; Ohno, Hiroyuki

    2016-02-18

    We examined the self-organization behavior of a designed amphiphilic molecule in 20 kinds of amino acid ionic liquids composed of 1-butyl-3-methylimidazolium cation and natural amino acid anion ([C4mim][AA]). Addition of [C4mim][AA], regardless of their anion species, to the amphiphile provided homogeneous mixtures showing lyotropic liquid-crystalline (LC) behavior. Upon increasing the component ratio of [C4mim][AA] in the mixtures, a successive change of the mesophase patterns from inverted hexagonal columnar, in some case via bicontinuous cubic, to layered phases was observed. By examining the LC properties at various temperatures and component ratios, we constructed lyotropic LC phase diagrams. Interestingly, the appearance of these phase diagrams is greatly different according to the selection of [AA]. Through comparison, we found that the self-organization behavior of an amphiphile in ionic liquids can be tuned by controlling their ability to form hydrogen-bond, van der Waals, and π-π interactions.

  11. Universal low-energy physics in 1D strongly repulsive multi-component Fermi gases

    NASA Astrophysics Data System (ADS)

    Jiang, Yuzhu; He, Peng; Guan, Xi-Wen

    2016-04-01

    It has been shown (Yang and You 2011 Chin. Phys. Lett. 28 020503) that at zero temperature the ground state of the one-dimensional (1D) w-component Fermi gas coincides with that of the spinless Bose gas in the limit ω \\to ∞ . This behavior was experimentally evidenced through quasi-1D tightly trapping ultracold 173Yb atoms in a recent paper (Pagano et al 2014 Nat. Phys. 10 198). However, understanding of low-temperature behavior of Fermi gases with a repulsive interaction requires spin-charge separated conformal field theories of an effective Tomonaga-Luttinger liquid and an antiferromagnetic SU(w) Heisenberg spin chain. Here we analytically derive universal thermodynamics of 1D strongly repulsive fermionic gases with SU(w) symmetry via the Yang-Yang thermodynamic Bethe ansatz method. The analytical free energy and magnetic properties of the systems at low temperature in a weak magnetic field are obtained through the Wiener-Hopf method. In particular, the free energy essentially manifests the spin-charge separated conformal field theories for high-symmetry systems with arbitrary repulsive interaction strength. We also find that the sound velocity of the Fermi gases in the large w limit coincides with that for the spinless Bose gas, whereas the spin velocity vanishes quickly as w becomes large. This indicates strong suppression of the Fermi exclusion statistics by the commutativity feature among the w-component fermions with different spin states in the Tomonaga-Luttinger liquid phase. Moreover, the equations of state and critical behavior of physical quantities at finite temperature are analytically derived in terms of the polylogarithm functions in the quantum critical region.

  12. Entropy excess in strongly correlated Fermi systems near a quantum critical point

    NASA Astrophysics Data System (ADS)

    Clark, J. W.; Zverev, M. V.; Khodel, V. A.

    2012-12-01

    A system of interacting, identical fermions described by standard Landau Fermi-liquid (FL) theory can experience a rearrangement of its Fermi surface if the correlations grow sufficiently strong, as occurs at a quantum critical point where the effective mass diverges. As yet, this phenomenon defies full understanding, but salient aspects of the non-Fermi-liquid (NFL) behavior observed beyond the quantum critical point are still accessible within the general framework of the Landau quasiparticle picture. Self-consistent solutions of the coupled Landau equations for the quasiparticle momentum distribution n(p) and quasiparticle energy spectrum ɛ(p) are shown to exist in two distinct classes, depending on coupling strength and on whether the quasiparticle interaction is regular or singular at zero momentum transfer. One class of solutions maintains the idempotency condition n2(p)=n(p) of standard FL theory at zero temperature T while adding pockets to the Fermi surface. The other solutions are characterized by a swelling of the Fermi surface and a flattening of the spectrum ɛ(p) over a range of momenta in which the quasiparticle occupancies lie between 0 and 1 even at T=0. The latter, non-idempotent solution is revealed by analysis of a Poincaré mapping associated with the fundamental Landau equation connecting n(p) and ɛ(p) and validated by solution of a variational condition that yields the symmetry-preserving ground state. Significantly, this extraordinary solution carries the burden of a large temperature-dependent excess entropy down to very low temperatures, threatening violation of the Nernst Theorem. It is argued that certain low-temperature phase transitions, notably those involving Cooper-pair formation, offer effective mechanisms for shedding the entropy excess. Available measurements in heavy-fermion compounds provide concrete support for such a scenario.

  13. Fermi at Six Months

    NASA Technical Reports Server (NTRS)

    Hays, Elizabeth

    2009-01-01

    An overview of the Fermi Gamma-ray Space Telescope's first 6 months in operation is provided. The Fermi Gamma-ray Space Telescope, formerly called GLAST, is a mission to measure the cosmic gamma-ray flux in the energy rage 20 MeV to more than 300 GeV, with supporting measurements for gamma-ray bursts from 8 keV to 30 MeV. It contains a Large Area Telescope capable of viewing the entire sky every 3 hours and a Gamma-ray Burst Monitor for viewing the entire unocculted sky. Since its launch on June 11, 2008 Fermi has provided information on pulsars, gamma ray bursts, relativistic jets, the active galactic nucleus, and a globular star cluster. This presentation describes Fermi's development, mission, instruments and recent findings.

  14. Fermi, Szilard and Trinity

    ERIC Educational Resources Information Center

    Anderson, Herbert L.

    1974-01-01

    The final installment of the author's recollections of his work with physicists Enrico Fermi, Leo Szilard and others in developing the first controlled nuclear chain reaction and in preparing the test explosion of the first atomic bomb. (GS)

  15. Fermi Galactic Center Zoom

    NASA Video Gallery

    This animation zooms into an image of the Milky Way, shown in visible light, and superimposes a gamma-ray map of the galactic center from NASA's Fermi. Raw data transitions to a view with all known...

  16. Bubbling behaviors induced by gas-liquid mixture permeating through a porous medium

    NASA Astrophysics Data System (ADS)

    Hu, Liang; Li, Mingbo; Chen, Wenyu; Xie, Haibo; Fu, Xin

    2016-08-01

    This paper investigates the bubbling behaviors induced by gas-liquid mixture permeating through porous medium (PM), which was observed in developing immersion lithography system and was found having great differences with traditional bubbling behaviors injected with only gas phase through the PM. An experimental setup was built up to investigate the bubbling characteristics affected by the mixed liquid phase. Both the flow regimes of gas-liquid mixture in micro-channel (upstream of the PM) and the bubbling flow regimes in water tank (downstream of the PM) were recorded synchronously by high-speed camera. The transitions between the flow regimes are governed by gas and liquid Weber numbers. Based on the image analysis, the characteristic parameters of bubbling region, including the diameter of bubbling area on PM surface, gas-phase volume flux, and dispersion angle of bubbles in suspending liquid, were studied under different proportions of gas and liquid flow rate. Corresponding empirical correlations were developed to describe and predict these parameters. Then, the pertinent bubble characteristics in different bubbling flow regimes were systematically investigated. Specifically, the bubble size distribution and the Sauter mean diameter affected by increasing liquid flow rate were studied, and the corresponding analysis was given based on the hydrodynamics of bubble-bubble and bubble-liquid interactions. According to dimensionless analysis, the general prediction equation of Sauter mean diameter under different operating conditions was proposed and confirmed by experimental data. The study of this paper is helpful to improve the collection performance of immersion lithography and aims to reveal the differences between the bubbling behaviors on PM caused by only gas flow and gas-liquid mixture flow, respectively, for the researches of fluid flow.

  17. Behavior of ultrasounds crossing perfluorocarbon liquids and random propagation times.

    PubMed

    Lacaze, Bernard

    2015-12-01

    Random propagation times are able to model waves attenuation and velocity. It is true for electromagnetic waves (light, radar, guided propagation) and also for acoustics and ultrasounds (acoustics for high frequencies). About the latter, it can be shown that stable probability laws are well-fitted for frequencies up to dozens of megahertz in numerous cases. Nowadays, medical applications are performed using propagation through perfluorocarbon (PFC). Experiments were done to measure attenuations and phase changes. Using these results, this paper addresses the question to know if stable probability laws can be used to characterize the propagation of ultrasounds through PFC liquids. PMID:26163738

  18. Behavior of ultrasounds crossing perfluorocarbon liquids and random propagation times.

    PubMed

    Lacaze, Bernard

    2015-12-01

    Random propagation times are able to model waves attenuation and velocity. It is true for electromagnetic waves (light, radar, guided propagation) and also for acoustics and ultrasounds (acoustics for high frequencies). About the latter, it can be shown that stable probability laws are well-fitted for frequencies up to dozens of megahertz in numerous cases. Nowadays, medical applications are performed using propagation through perfluorocarbon (PFC). Experiments were done to measure attenuations and phase changes. Using these results, this paper addresses the question to know if stable probability laws can be used to characterize the propagation of ultrasounds through PFC liquids.

  19. Numerical Modeling of Inclusion Behavior in Liquid Metal Processing

    NASA Astrophysics Data System (ADS)

    Bellot, Jean-Pierre; Descotes, Vincent; Jardy, Alain

    2013-09-01

    Thermomechanical performance of metallic alloys is directly related to the metal cleanliness that has always been a challenge for metallurgists. During liquid metal processing, particles can grow or decrease in size either by mass transfer with the liquid phase or by agglomeration/fragmentation mechanisms. As a function of numerical density of inclusions and of the hydrodynamics of the reactor, different numerical modeling approaches are proposed; in the case of an isolated particle, the Lagrangian technique coupled with a dissolution model is applied, whereas in the opposite case of large inclusion phase concentration, the population balance equation must be solved. Three examples of numerical modeling studies achieved at Institut Jean Lamour are discussed. They illustrate the application of the Lagrangian technique (for isolated exogenous inclusion in titanium bath) and the Eulerian technique without or with the aggregation process: for precipitation and growing of inclusions at the solidification front of a Maraging steel, and for endogenous inclusions in the molten steel bath of a gas-stirred ladle, respectively.

  20. High temperature interaction behavior at liquid metal-ceramic interfaces

    NASA Astrophysics Data System (ADS)

    McDeavitt, S. M.; Billings, G. W.; Indacochea, J. E.

    2002-08-01

    Liquid metal/ceramic interaction experiments were undertaken at elevated temperatures with the purpose of developing reusable crucibles for melting reactive metals. The metals used in this work included zirconium (Zr), Zr-8 wt.% stainless steel, and stainless steel containing 15 wt.% Zr. The ceramic substrates include yttria, Zr carbide, and hafnium (Hf) carbide. The metal-ceramic samples were placed on top of a tungsten (W) dish. These experiments were conducted with the temperature increasing at a controlled rate until reaching set points above 2000 °C; the systems were held at the peak temperature for about five min and then cooled. The atmosphere in the furnace was argon (Ar). An outside video recording system was used to monitor the changes on heating up and cooling down. All samples underwent a post-test metallurgical examination. Pure Zr was found to react with yttria, resulting in oxygen (O) evolution at the liquid metal-ceramic interface. In addition, dissolved O was observed in the as-cooled Zr metal. Yttrium (Y) was also present in the Zr metal, but it had segregated to the grain boundaries on cooling. Despite the normal expectations for reactive wetting, no transition interface was developed, but the Zr metal was tightly bound to yttria ceramic. Similar reactions occurred between the yttria and the Zr-stainless steel alloys. Two other ceramic samples were Zr carbide and Hf carbide; both carbide substrates were wetted readily by the molten Zr, which flowed easily to the sides of the substrates. The molten Zr caused a very limited dissolution of the Zr carbide, and it reacted more strongly with the Hf carbide. These reactive wetting results are relevant to the design of interfaces and the development of reactive filler metals for the fabrication of high temperature components through metal-ceramic joining. Parameters that have a marked impact on this interface reaction include the thermodynamic stability of the substrate, the properties of the modified

  1. Universal thermodynamics of a strongly interacting Fermi gas: theory versus experiment

    NASA Astrophysics Data System (ADS)

    Hu, Hui; Liu, Xia-Ji; Drummond, Peter D.

    2010-06-01

    Strongly interacting, dilute Fermi gases exhibit a scale-invariant, universal thermodynamic behavior. This is notoriously difficult to understand theoretically because of the absence of a small interaction parameter. Here, we present a systematic comparison of theoretical predictions from different quantum many-body theories with recent experimental data of Nascimbne et al (2010 Nature 463 1057). Our comparisons have no adjustable parameters, either theoretically or experimentally. All the model approximations seem to fluctuate rather than converge on the experimental data. It turns out that a simple Gaussian pair fluctuation theory gives the best quantitative agreement, except at the critical superfluid transition region. In the normal state, we also calculate the equation of state by using a quantum cluster expansion theory and explore in detail its applicability to low temperatures. Using the accurate experimental result for the thermodynamic function S(T), we determine the temperature T of a trapped Fermi gas at unitarity as a function of a non-interacting temperature Ti, which can be obtained by an adiabatic sweep to the free gas limit. By analyzing the recent experimental data, we find a characteristic temperature (T/TF)0=0.19±0.02 or (Ti/TF)0=0.16±0.02 in a harmonic trap, below which there are deviations from normal Fermi-liquid-like behavior that may be attributed to pairing effects. Here, TF is the Fermi temperature for a trapped ideal, non-interacting Fermi gas. Our thorough comparison may shed light on the further theoretical development of strongly interacting fermions.

  2. Dielectric Relaxation and Rheological Behavior of Supramolecular Polymeric Liquid

    SciTech Connect

    Lou, Nan; Wang, Yangyang; Li, Xiaopeng; Li, Haixia; Wang, Ping

    2013-01-01

    A model self-complementary supramolecular polymer based on thymine and diamidopyridine triple hydrogen-bonding motifs has been synthesized, and its dielectric and rheological behavior has been investigated. The formation of supramolecular polymers has been unequivocally demonstrated by nuclear magnetic resonance, electrospray ionization mass spectrometry with traveling wave ion mobility separation, dielectric spectroscopy, and rheology. The dynamical behaviors of this associating polymer generally conform to those of type-A polymers, with a low-frequency chain relaxation and a high-frequency relaxation visible in both rheological and dielectric measurements. The dielectric chain relaxation shows the ideal symmetric Debye-like shape, resembling the peculiar features of hydrogen-bonding monoalcohols. Detailed analysis shows that there exists a weak decoupling between the mechanical terminal relaxation and dielectric Debye-like relaxation. The origin of the Debye-like dielectric relaxation is further discussed in the light of monoalcohols.

  3. Luttinger Liquid, Singular Interaction and Quantum Criticality in Cuprate Materials

    NASA Astrophysics Data System (ADS)

    di Castro, C.; Caprara, S.

    2014-10-01

    With particular reference to the role of the renormalization group (RG) approach and Ward identities (WI's), we start by recalling some old features of the one-dimensional Luttinger liquid as the prototype of non-Fermi-liquid behavior. Its dimensional crossover to the Landau normal Fermi liquid implies that a non-Fermi liquid, as, e.g., the normal phase of the cuprate high temperature superconductors, can be maintained in d > 1 only in the presence of a sufficiently singular effective interaction among the charge carriers. This is the case when, nearby an instability, the interaction is mediated by critical fluctuations. We are then led to introduce the specific case of superconductivity in cuprates as an example of avoided quantum criticality. We will disentangle the fluctuations which act as mediators of singular electron-electron interaction, enlightening the possible order competing with superconductivity and a mechanism for the non-Fermi-liquid behavior of the metallic phase. This paper is not meant to be a comprehensive review. Many important contributions will not be considered. We will also avoid using extensive technicalities and making full calculations for which we refer to the original papers and to the many good available reviews. We will here only follow one line of reasoning which guided our research activity in this field.

  4. Anisotropic behavior of water in ferroelectric liquid crystals.

    PubMed

    Singh, G; Choudhary, A; Prakash, G Vijaya; Biradar, A M

    2010-05-01

    The outcome of water addition in ferroelectric liquid crystal (FLC) has been investigated in uniform and defect-free homogeneous and homeotropically aligned monodomain sample cells from electro-optical and dielectric spectroscopic measurements. The lagging in optical response between nonconducting (spatially variable switching) and conducting (conventional switching) portions of water added FLC sample cell has been observed by frequency-dependent electro-optical studies. The bias-dependent water related new relaxation peak near the conventional Goldstone mode relaxation process has been observed only in the homogeneous alignment and not in the homeotropic one. Further, the significant increment in dielectric anisotropy as well as faster diffusion of water along long molecular axis than short molecular axis has also been monitored. These studies strongly suggest that the distribution of water is anisotropic in FLC medium and could be the reason for new relaxation peak in the water added FLC sample. PMID:20866247

  5. Cooper pairing above the critical temperature in a unitary Fermi gas.

    PubMed

    Wlazłowski, Gabriel; Magierski, Piotr; Drut, Joaquín E; Bulgac, Aurel; Roche, Kenneth J

    2013-03-01

    We present an ab initio determination of the spin response of the unitary Fermi gas. Based on finite temperature quantum Monte Carlo calculations and the Kubo linear-response formalism, we determine the temperature dependence of the spin susceptibility and the spin conductivity. We show that both quantities exhibit suppression above the critical temperature of the superfluid-to-normal phase transition due to Cooper pairing. The spin diffusion transport coefficient does not display a minimum in the vicinity of the critical temperature and drops to very low values D(s)≈0.8ħ/m in the superfluid phase. All these spin observables show a smooth and monotonic behavior with temperature when crossing the critical temperature T(c), until the Fermi liquid regime is attained at the temperature T(*), above which the pseudogap regime disappears.

  6. Mechanical behavior of a fluid-sensitive material during liquid diffusion

    NASA Astrophysics Data System (ADS)

    Widiastuti, Indah; Sbarski, Igor; Masood, S. H.

    2014-05-01

    This paper described the analytical study that we performed in an attempt to understand the combined effect of liquid diffusion and temperature on the mechanical response of viscoelastic liquid-sensitive material. A constitutive equation for linear viscoelasticity, which includes the effect of liquid diffusion, is used to model the mechanical response of a fluid-sensitive polymer such as PLA-based bioplastic. The viscoelastic characteristics which represent material degradation due to liquid diffusion were expressed using a creep-based formulation represented by Burger's model. Creep experiment data were fitted to the Burgers model to provide a liquid content-dependent set of input data for subsequent time-dependent analysis. Further, analytical solutions for stresses and deformations were obtained from the corresponding elastic solution by applying the Correspondence Principle, using previously defined material characteristics. Spatial and time variations of stress and deformation were evaluated to give a precise description of the material behavior under hygroscopic conditions. We propose a stress concentration factor to take into account the liquid diffusion-induced stress that may result in a failure of an application. The results emphasize the importance of considering liquid diffusion and viscoelastic properties in the design of components using liquid-absorbable material.

  7. Analysis of the free-fall behavior of liquid-metal drops in a gaseous atmosphere

    NASA Technical Reports Server (NTRS)

    Mccoy, J. Kevin; Markworth, Alan J.; Collings, E. W.; Brodkey, Robert S.

    1987-01-01

    The free-fall of a liquid-metal drop and heat transfer from the drop to its environment are described for both a gaseous atmosphere and vacuum. A simple model, in which the drop is assumed to fall rectilinearly with behavior like that of a rigid particle, is developed first, then possible causes of deviation from this behavior are discussed. The model is applied to describe solidification of drops in a drop tube. Possible future developments of the model are suggested.

  8. Pretransitional behavior of the nonlinear dielectric effect for the liquid-solid transition in nitrobenzene

    NASA Astrophysics Data System (ADS)

    Drozd-Rzoska, Aleksandra; Rzoska, Sylwester J.; Rzoska, Agata Angelika

    2016-06-01

    The nonlinear dielectric effect describes changes of dielectric permittivity induced by the strong electric field. This report shows the evidence for the critical-like pretransitional behavior for the liquid-solid transition in the supercooled nitrobenzene. Hallmarks of such behavior extend even above the melting temperature. A method for the analysis of pretransitional effects, avoiding the biasing impact of the noncritical background contribution, is proposed.

  9. Fibroblast behavior at aqueous interfaces with perfluorocarbon, silicone, and fluorosilicone liquids.

    PubMed

    Sparrow, J R; Ortiz, R; MacLeish, P R; Chang, S

    1990-04-01

    Perfluorocarbon, silicone, and fluorosilicone liquids with potential for use as vitreous substitutes in the management of complex retinal detachment were evaluated for surface reactivity by assessing the behavior of anchorage-dependent fibroblasts plated at the phase boundary between these compounds and culture medium. Low-viscosity perfluorcarbons were alumina-treated to remove polar impurities. On perfluorodecalin, perfluorodimethylcyclohexane, perfluorotrimethylcyclohexane, perfluoroethylcyclohexane, perfluorooctane, perfluoroperhydrophenanthrene, perfluoromethyladamantane, perfluorodimethyladamantane, the highly viscous perfluoropolyether liquids Krytox TLF7067 and 6354, and dimethylsiloxane liquids of a variety of viscosities, most cells did not attach; the few that did attach exhibited minimal spreading behavior and did not achieve the flattened spindle-shape morphology which is a prerequisite to normal proliferative activity. Conversely, on perfluoromethyldecaline, perfluorofluorene, perfluorotributylamine, the perfluoropolyether K-6 hexamer, trifluoropropylmethylsiloxane (fluorosilicone), and diphenyldimethylsiloxane, some cells became fusiform-shaped and exhibited proliferation, the extent of which varied with the compound. The association of alumina treatment of perfluorocarbon liquids with a reduction in cell growth was indicative of a relationship between the presence of residual hydrogen-containing impurities and the capacity for cellular attachment and growth. This correlation was demonstrated also in experiments in which cell attachment and growth was facilitated by the addition of hydrogen-rich monohydroperfluorooctane to alumina-treated perfluorooctane. In conclusion, evidence for the presence of surface active impurities in liquid vitreous substitute materials can be obtained by observing the behavior of attachment-dependent cells plated at the boundary between these compounds and culture medium.

  10. Infiltration behavior of sintering liquid on nuclei ores during low-titanium ore sintering process

    NASA Astrophysics Data System (ADS)

    Liu, Dong-hui; Zhang, Jian-liang; Xue, Xun; Wang, Guang-wei; Li, Ke-jiang; Liu, Zheng-jian

    2016-06-01

    Sinter strength is dependent not only on the self-intensity of the residual rude and bonding phase but also on the bonding degree between them. The infiltration behavior of sintering liquid on nuclei ores influences the bonding degree, which ultimately determines the sinter strength. Infiltration tests were conducted using micro-sinter equipment. The infiltration area index of original liquid (IAO), infiltration volume index of secondary liquid (IVS), and sinter body bonding strength (SBS) were proposed to study the melt infiltration behavior. The results show that the IVS first increases and then decreases with increasing TiO2 content in adhering fines, whereas the IAO exhibits the opposite behavior. Compared with the original liquid, the secondary liquid shows lower porosity, smaller pores, and more uniform distribution. The SBS increases first and then decreases with increasing IAO and TiO2 content, and reaches a maximum when the IAO and TiO2 contents are approximately 0.5 and 2.0wt%, respectively. The SBS first increases and then tends to be stable with increasing IVS. The TiO2 content is suggested to be controlled to approximately 2.0wt% in low-titanium ore sintering.

  11. Understanding the impact of the central atom on the ionic liquid behavior: Phosphonium vs ammonium cations

    NASA Astrophysics Data System (ADS)

    Carvalho, Pedro J.; Ventura, Sónia P. M.; Batista, Marta L. S.; Schröder, Bernd; Gonçalves, Fernando; Esperança, José; Mutelet, Fabrice; Coutinho, João A. P.

    2014-02-01

    The influence of the cation's central atom in the behavior of pairs of ammonium- and phosphonium-based ionic liquids was investigated through the measurement of densities, viscosities, melting temperatures, activity coefficients at infinite dilution, refractive indices, and toxicity against Vibrio fischeri. All the properties investigated are affected by the cation's central atom nature, with ammonium-based ionic liquids presenting higher densities, viscosities, melting temperatures, and enthalpies. Activity coefficients at infinite dilution show the ammonium-based ionic liquids to present slightly higher infinite dilution activity coefficients for non-polar solvents, becoming slightly lower for polar solvents, suggesting that the ammonium-based ionic liquids present somewhat higher polarities. In good agreement these compounds present lower toxicities than the phosphonium congeners. To explain this behavior quantum chemical gas phase DFT calculations were performed on isolated ion pairs at the BP-TZVP level of theory. Electronic density results were used to derive electrostatic potentials of the identified minimum conformers. Electrostatic potential-derived CHelpG and Natural Population Analysis charges show the P atom of the tetraalkylphosphonium-based ionic liquids cation to be more positively charged than the N atom in the tetraalkylammonium-based analogous IL cation, and a noticeable charge delocalization occurring in the tetraalkylammonium cation, when compared with the respective phosphonium congener. It is argued that this charge delocalization is responsible for the enhanced polarity observed on the ammonium based ionic liquids explaining the changes in the thermophysical properties observed.

  12. Understanding the impact of the central atom on the ionic liquid behavior: Phosphonium vs ammonium cations

    SciTech Connect

    Carvalho, Pedro J.; Ventura, Sónia P. M.; Batista, Marta L. S.; Schröder, Bernd; Coutinho, João A. P.; Gonçalves, Fernando; Esperança, José; Mutelet, Fabrice

    2014-02-14

    The influence of the cation's central atom in the behavior of pairs of ammonium- and phosphonium-based ionic liquids was investigated through the measurement of densities, viscosities, melting temperatures, activity coefficients at infinite dilution, refractive indices, and toxicity against Vibrio fischeri. All the properties investigated are affected by the cation's central atom nature, with ammonium-based ionic liquids presenting higher densities, viscosities, melting temperatures, and enthalpies. Activity coefficients at infinite dilution show the ammonium-based ionic liquids to present slightly higher infinite dilution activity coefficients for non-polar solvents, becoming slightly lower for polar solvents, suggesting that the ammonium-based ionic liquids present somewhat higher polarities. In good agreement these compounds present lower toxicities than the phosphonium congeners. To explain this behavior quantum chemical gas phase DFT calculations were performed on isolated ion pairs at the BP-TZVP level of theory. Electronic density results were used to derive electrostatic potentials of the identified minimum conformers. Electrostatic potential-derived CHelpG and Natural Population Analysis charges show the P atom of the tetraalkylphosphonium-based ionic liquids cation to be more positively charged than the N atom in the tetraalkylammonium-based analogous IL cation, and a noticeable charge delocalization occurring in the tetraalkylammonium cation, when compared with the respective phosphonium congener. It is argued that this charge delocalization is responsible for the enhanced polarity observed on the ammonium based ionic liquids explaining the changes in the thermophysical properties observed.

  13. Magnetic field induced motion behavior of gas bubbles in liquid

    PubMed Central

    Wang, Keliang; Pei, Pucheng; Pei, Yu; Ma, Ze; Xu, Huachi; Chen, Dongfang

    2016-01-01

    The oxygen evolution reaction generally exists in electrochemical reactions. It is a ubiquitous problem about how to control the motion of oxygen bubbles released by the reaction. Here we show that oxygen bubbles during oxygen evolution reaction exhibit a variety of movement patterns in the magnetic field, including directional migration and rotational motion of oxygen bubbles when the magnet in parallel with the electrode, and exclusion movement of oxygen bubbles when the magnet perpendicular to the electrode. The results demonstrate that the direction of oxygen bubbles movement is dependent upon the magnet pole near the electrode, and the kinetics of oxygen bubbles is mainly proportional to intensity of the electromagnetic field. The magnetic-field induced rotational motion of oxygen bubbles in a square electrolyzer can increase liquid hydrodynamics, thus solve the problems of oxygen bubbles coalescence, and uneven distribution of electrolyte composition and temperature. These types of oxygen bubbles movement will not only improve energy saving and metal deposition for energy storage and metal refinery, but also propel object motion in application to medical and martial fields. PMID:26867515

  14. Magnetic field induced motion behavior of gas bubbles in liquid.

    PubMed

    Wang, Keliang; Pei, Pucheng; Pei, Yu; Ma, Ze; Xu, Huachi; Chen, Dongfang

    2016-02-12

    The oxygen evolution reaction generally exists in electrochemical reactions. It is a ubiquitous problem about how to control the motion of oxygen bubbles released by the reaction. Here we show that oxygen bubbles during oxygen evolution reaction exhibit a variety of movement patterns in the magnetic field, including directional migration and rotational motion of oxygen bubbles when the magnet in parallel with the electrode, and exclusion movement of oxygen bubbles when the magnet perpendicular to the electrode. The results demonstrate that the direction of oxygen bubbles movement is dependent upon the magnet pole near the electrode, and the kinetics of oxygen bubbles is mainly proportional to intensity of the electromagnetic field. The magnetic-field induced rotational motion of oxygen bubbles in a square electrolyzer can increase liquid hydrodynamics, thus solve the problems of oxygen bubbles coalescence, and uneven distribution of electrolyte composition and temperature. These types of oxygen bubbles movement will not only improve energy saving and metal deposition for energy storage and metal refinery, but also propel object motion in application to medical and martial fields.

  15. Magnetic field induced motion behavior of gas bubbles in liquid

    NASA Astrophysics Data System (ADS)

    Wang, Keliang; Pei, Pucheng; Pei, Yu; Ma, Ze; Xu, Huachi; Chen, Dongfang

    2016-02-01

    The oxygen evolution reaction generally exists in electrochemical reactions. It is a ubiquitous problem about how to control the motion of oxygen bubbles released by the reaction. Here we show that oxygen bubbles during oxygen evolution reaction exhibit a variety of movement patterns in the magnetic field, including directional migration and rotational motion of oxygen bubbles when the magnet in parallel with the electrode, and exclusion movement of oxygen bubbles when the magnet perpendicular to the electrode. The results demonstrate that the direction of oxygen bubbles movement is dependent upon the magnet pole near the electrode, and the kinetics of oxygen bubbles is mainly proportional to intensity of the electromagnetic field. The magnetic-field induced rotational motion of oxygen bubbles in a square electrolyzer can increase liquid hydrodynamics, thus solve the problems of oxygen bubbles coalescence, and uneven distribution of electrolyte composition and temperature. These types of oxygen bubbles movement will not only improve energy saving and metal deposition for energy storage and metal refinery, but also propel object motion in application to medical and martial fields.

  16. Entropy excess in strongly correlated Fermi systems near a quantum critical point

    SciTech Connect

    Clark, J.W.; Zverev, M.V.; Khodel, V.A.

    2012-12-15

    A system of interacting, identical fermions described by standard Landau Fermi-liquid (FL) theory can experience a rearrangement of its Fermi surface if the correlations grow sufficiently strong, as occurs at a quantum critical point where the effective mass diverges. As yet, this phenomenon defies full understanding, but salient aspects of the non-Fermi-liquid (NFL) behavior observed beyond the quantum critical point are still accessible within the general framework of the Landau quasiparticle picture. Self-consistent solutions of the coupled Landau equations for the quasiparticle momentum distribution n(p) and quasiparticle energy spectrum {epsilon}(p) are shown to exist in two distinct classes, depending on coupling strength and on whether the quasiparticle interaction is regular or singular at zero momentum transfer. One class of solutions maintains the idempotency condition n{sup 2}(p)=n(p) of standard FL theory at zero temperature T while adding pockets to the Fermi surface. The other solutions are characterized by a swelling of the Fermi surface and a flattening of the spectrum {epsilon}(p) over a range of momenta in which the quasiparticle occupancies lie between 0 and 1 even at T=0. The latter, non-idempotent solution is revealed by analysis of a Poincare mapping associated with the fundamental Landau equation connecting n(p) and {epsilon}(p) and validated by solution of a variational condition that yields the symmetry-preserving ground state. Significantly, this extraordinary solution carries the burden of a large temperature-dependent excess entropy down to very low temperatures, threatening violation of the Nernst Theorem. It is argued that certain low-temperature phase transitions, notably those involving Cooper-pair formation, offer effective mechanisms for shedding the entropy excess. Available measurements in heavy-fermion compounds provide concrete support for such a scenario. - Highlights: Black-Right-Pointing-Pointer Extension of Landau

  17. Phase and Topological Behavior of Lyotropic Chromonic Liquid Crystals in Double Emulsions

    NASA Astrophysics Data System (ADS)

    Davidson, Zoey S.; Jeong, Joonwoo; Tu, Fuquan; Lohr, Matt; Lee, Daeyeon; Collings, Peter J.; Lubensky, Tom C.; Yodh, A. G.

    2013-03-01

    Lyotropic chromonic liquid crystals, assembled by non-covalent interactions, have fascinating temperature- and concentration-dependent phase behavior. Using water-oil-water double emulsions, we are able control the inner droplet chromonic phase concentration by osmosis through the oil phase. We then study the configurations of the chromonic liquid crystal phases in droplets by varying the oil types, oil soluble surfactants, and inner droplet diameter. We employ polarization microscopy to observe resulting nematic and columnar phases of Sunset Yellow FCF, and we deduce the liquid crystal configuration of both phases within the droplets. Simulations based on Jones matrices confirm droplet appearance, and preliminary observations of chromonic liquid crystal shells in oil-water-oil double emulsions are reported. Supported by UPenn MRSEC DMR 11-20901 and NSF DMR 12-05463

  18. Sharper Fermi LAT Images

    NASA Astrophysics Data System (ADS)

    Portillo, Stephen; Finkbeiner, Douglas P.

    2015-01-01

    The Large Area Telescope on the Fermi Gamma-ray Space Telescope has a point spread function with large tails, consisting of events affected by tracker ineffiencies, inactive volumes, and hard scattering; these tails can make source confusion a limiting factor. The parameter CTBCORE, available in the publicly available Extended Fermi LAT data, estimates the quality of each event's direction reconstruction; by implementing a cut in this parameter, the tails of the point spread function can be suppressed at the cost of losing effective area. We implement cuts on CTBCORE and present updated instrument response functions derived from the Fermi LAT data itself, along with all-sky maps generated with these cuts. Having shown the effectiveness of these cuts, especially at low energies, we encourage their use in analyses where angular resolution is more important than Poisson noise.

  19. Impact of Liquid-Vapor to Liquid-Liquid-Vapor Phase Transitions on Asphaltene-Rich Nanoaggregate Behavior in Athabasca Vacuum Residue + Pentane Mixtures

    SciTech Connect

    Long, Bingwen; Chodakowski, Martin; Shaw, John M.

    2013-06-05

    The bulk phase behavior of heavy oil + alkane mixtures and the behavior of the asphaltenes that they contain are topics of importance for the design and optimization of processes for petroleum production, transport, and refining and for performing routine saturates, aromatics, resins, and asphaltenes (SARA) analyses. In prior studies, partial phase diagrams and phase behavior models for Athabasca vacuum residue (AVR) comprising 32 wt % pentane asphaltenes + n-alkanes were reported. For mixtures with pentane, observed phase behaviors included single-phase liquid as well as liquid–liquid, liquid–liquid–vapor, and liquid–liquid–liquid–vapor regions. Dispersed solids were detected under some conditions as well but not quantified. In this work, small-angle X-ray scattering (SAXS) is used to study nanostructured materials in liquid phases present in AVR + n-pentane mixtures from 50 to 170 °C at mixture bubble pressure. The investigation focuses on the impact of the transition from a single AVR-rich liquid to co-existing pentane-rich and AVR-rich liquids on the nanostructure and the nanostructures most resistant to aggregation as the pentane composition axis is approached. Background scattering subtraction was performed using global mixture composition. The robustness of this assumption with respect to values obtained for coefficients appearing in a two level Beaucage unified equation fit is demonstrated. The nanostructured material is shown to arise at two length scales from 1 to 100 wt % AVR. Smaller nanostructures possess mean radii less than 50 Å, while the larger nanostructures possess mean radii greater than 250 Å. The addition of pentane to the AVR causes an increasingly large fraction of the large and small nanostructures to grow in size. Only nanostructures resistant to aggregation remain in the pentane-rich phase as the 0 wt % AVR axis is approached. Step changes in aggregation identified from changes in average radius of gyration, scattering

  20. Physics of ultracold Fermi gases revealed by spectroscopies

    NASA Astrophysics Data System (ADS)

    Törmä, Päivi

    2016-04-01

    This article provides a brief review of how various spectroscopies have been used to investitage many-body quantum phenomena in the context of ultracold Fermi gases. In particular, work done with RF spectroscopy, Bragg spectroscopy and lattice modulation spectroscopy is considered. The theoretical basis of these spectroscopies, namely linear response theory in the many-body quantum physics context is briefly presented. Experiments related to the BCS-BEC crossover, imbalanced Fermi gases, polarons, possible pseudogap and Fermi liquid behaviour and measuring the contact are discussed. Remaining open problems and goals in the field are sketched from the perspective how spectroscopies could contribute.

  1. FermiGrid

    SciTech Connect

    Yocum, D.R.; Berman, E.; Canal, P.; Chadwick, K.; Hesselroth, T.; Garzoglio, G.; Levshina, T.; Sergeev, V.; Sfiligoi, I.; Sharma, N.; Timm, S.; /Fermilab

    2007-05-01

    As one of the founding members of the Open Science Grid Consortium (OSG), Fermilab enables coherent access to its production resources through the Grid infrastructure system called FermiGrid. This system successfully provides for centrally managed grid services, opportunistic resource access, development of OSG Interfaces for Fermilab, and an interface to the Fermilab dCache system. FermiGrid supports virtual organizations (VOs) including high energy physics experiments (USCMS, MINOS, D0, CDF, ILC), astrophysics experiments (SDSS, Auger, DES), biology experiments (GADU, Nanohub) and educational activities.

  2. Lederman wins Fermi award

    SciTech Connect

    Not Available

    1993-09-01

    Leon Lederman has received the 1992 Enrico Fermi Award, presented in recognition of a lifetime of achievement in nuclear energy. This article briefly details Lederman's award-winning work (1988 Nobel Proze in Physics) in high-energy physics -- his discovery of the upsilon particle and the muon neutrino. His leadership in the creation of the superconducting accelerator at Fermilab and his leadership in science education of society are also cited with respect to the Enrico Fermi Award. Specifics on the award and its presentation are included in this article.

  3. Liquid and glass polymorphism in a monatomic system with isotropic, smooth pair interactions.

    PubMed

    Abraham, Joel Y; Buldyrev, Sergey V; Giovambattista, Nicolas

    2011-12-01

    Systems of particles with interactions given by the Jagla core-softened pair potential are known to exhibit water-like thermodynamic anomalies and a liquid-liquid phase transition. The drawback of the Jagla potential is that it is characterized by discontinuous forces acting between particles and thus is not suitable for standard molecular dynamics (MD) simulations. Here we introduce a smooth version of the Jagla potential based on two Fermi distributions and study the properties of a system of particles interacting via this new "Fermi-Jagla" pair potential by using standard MD simulations. We find that the liquid based on the Fermi-Jagla potential retains most of the properties of the liquid based on the original Jagla potential. Namely, it exhibits the following water-like anomalies: (i) decrease of density, (ii) increase of compressibility, κ(T)(T,P), and (iii) increase of isobaric specific heat, C(P)(T,P), upon isobaric cooling, and (iv) increase of diffusivity upon isothermal compression. The Fermi-Jagla potential also exhibits (i') density minima, (ii') compressibility minima, (iii') isobaric specific heat minima upon isobaric cooling, and (iv') diffusivity minima upon isothermal compression. As in the Jagla model case, we find a liquid-liquid phase transition (LLPT) and a liquid-liquid critical point in the equilibrium liquid. Contrary to the case of the original Jagla model liquid, the LLPT line for the Fermi-Jagla potential has a negative slope in the P-T plane that extends well above the crystallization temperature. This feature makes the Fermi-Jagla potential a better candidate to reproduce the behavior of tetrahedral liquids including water, for which the LLPT line observed in simulations has also negative slope. In the glass state, the Fermi-Jagla pair potential results in reversible polyamorphism between low- and high-density amorphous solids (LDA and HDA, respectively). We also find that HDA results from pressure-induced amorphization of the model

  4. The effect of oxygen as a light element in metallic liquids on partitioning behavior

    NASA Astrophysics Data System (ADS)

    Chabot, Nancy L.; Wollack, E. Alex; Humayun, Munir; Shank, Ellen M.

    2015-04-01

    Oxygen has been considered a potentially important light element in metallic liquids during a range of planetary processes, yet the influence of O in a metallic melt on element partitioning behavior is largely unknown. To investigate the effect of O in such systems, we conducted experiments in the Fe-S-O system, doped with 25 trace elements, which produced two immiscible metallic liquids. Our results indicate that the presence of O in the metallic liquid produces a distinctive chemical signature for W and Ga in particular. Tungsten shows an affinity for O in the metallic liquid and partitions more strongly into the metallic melt in the presence of O. The partitioning of Ga is relatively constant despite the presence of O, which is in contrast to the majority of the other siderophile elements in the study. Our experiments from 1400 to 1600 °C show no significant effect from temperature on the partitioning behavior of any trace elements over this limited temperature range. This distinctive chemical signature due to the presence of O in the metallic liquid has potential implications for modeling core formation, evaluating isotopic signatures produced by core crystallization, and interpreting chemical assemblages observed in meteorites.

  5. Traction and nonequilibrium phase behavior of confined sheared liquids at high pressure

    NASA Astrophysics Data System (ADS)

    Gattinoni, Chiara; Heyes, David M.; Lorenz, Christian D.; Dini, Daniele

    2013-11-01

    Nonequilibrium molecular dynamics simulations of confined model liquids under pressure and sheared by the relative sliding of the boundary walls have been carried out. The relationship between the time-dependent traction coefficient, μ(t), and the state of internal structure of the film is followed from commencement of shear for various control parameters, such as applied load, global shear rate, and solid-liquid atom interaction parameters. Phase diagrams, velocity and temperature profiles, and traction coefficient diagrams are analyzed for pure Lennard-Jones (LJ) liquids and a binary LJ mixture. A single component LJ liquid is found to form semicrystalline arrangements with high-traction coefficients, and stick-slip behavior is observed for high pressures and low-shear velocities, which is shown to involve periodic deformation and stress release of the wall atoms and slip in the solid-liquid boundary region. A binary mixture, which discourages crystallization, gives a more classical tribological response with the larger atoms preferentially adsorbing commensurate with the wall. The results obtained are analyzed in the context of tribology: the binary mixture behaves like a typical lubricant, whereas the monatomic system behaves like a traction fluid. It is discussed how this type of simulation can give insights on the tribological behavior of realistic systems.

  6. Thermal-hydraulic behaviors of vapor-liquid interface due to arrival of a pressure wave

    SciTech Connect

    Inoue, Akira; Fujii, Yoshifumi; Matsuzaki, Mitsuo

    1995-09-01

    In the vapor explosion, a pressure wave (shock wave) plays a fundamental role for triggering, propagation and enhancement of the explosion. Energy of the explosion is related to the magnitude of heat transfer rate from hot liquid to cold volatile one. This is related to an increasing rate of interface area and to an amount of transient heat flux between the liquids. In this study, the characteristics of transient heat transfer and behaviors of vapor film both on the platinum tube and on the hot melt tin drop, under same boundary conditions have been investigated. It is considered that there exists a fundamental mechanism of the explosion in the initial expansion process of the hot liquid drop immediately after arrival of pressure wave. The growth rate of the vapor film is much faster on the hot liquid than that on the solid surface. Two kinds of roughness were observed, one due to the Taylor instability, by rapid growth of the explosion bubble, and another, nucleation sites were observed at the vapor-liquid interface. Based on detailed observation of early stage interface behaviors after arrival of a pressure wave, the thermal fragmentation mechanism is proposed.

  7. Effect of dimethylpolysiloxane liquid on the cryogenic tensile strength and thermal contraction behavior of epoxy resins

    NASA Astrophysics Data System (ADS)

    Yi, Jin Woo; Lee, Yu Jin; Lee, Sang Bok; Lee, Wonoh; Um, Moon Kwang

    2014-05-01

    Dimethylpolysiloxane liquid was blended with diglycidyl ether of bisphenol-A epoxy resin including anhydride curing agent to improve the tensile strength of the epoxy resin at 77 K without any increase in its coefficient of thermal expansion (CTE). A bifunctional polymer, silicone-modified epoxy resin (SME), was also added to the mixture as a compatibilizer. The results of UV transmittance for the blend resin showed that the incorporation of the SME could stabilize effectively spherical domains of the siloxane liquid which was immiscible with the epoxy matrix. The tensile strengths of the blend resins at both room temperature and 77 K were measured and SEM analysis for the fractured cross sections was carried out to verify the toughening behavior of the liquid droplets. The results indicated that even small amount of addition of the siloxane liquid (0.05 phr) coupled with SME (20 phr) could enhance the tensile strength at 77 K by 77.6% compared to that of the neat epoxy resin. This improvement is attributed to the fact that the solid and s droplets can disperse the localized stress and interrupt the crack propagation by cavitation mechanism followed by multiple generation of numerous micro-deformation. From the CTE measurement, the siloxane liquid has no influence on the thermal contraction behavior of the blend resin.

  8. Lyotropic Phase Behavior of Polybutadiene-Poly(ethylene oxide) Diblock Copolymers in Ionic Liquids

    SciTech Connect

    Simone, Peter M.; Lodge, Timothy P.

    2008-08-26

    The lyotropic phase behavior of three poly(1,2-butadiene-b-ethylene oxide) diblock copolymers (PB-PEO) with different monomer volume fractions has been studied in two different ionic liquids, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMI][PF{sub 6}]), across the complete concentration range. The ordered microstructures present in the solutions were characterized via small-angle X-ray scattering (SAXS). The phase diagrams for the PB-PEO/ionic liquid solutions include regions corresponding to the classical copolymer microstructures: body-centered-cubic lattices of spheres, hexagonally ordered cylinders, and lamellae. Additionally, the phase diagrams also include wide regions of coexisting microstructures and regions apparently corresponding to a disordered network microstructure. The phase behavior of the PB-PEO copolymers in both ionic liquids was comparable to their previously reported aqueous solution behavior. The temperature dependence of the phase diagrams was very modest, indicative of a highly segregated system. The level of solvent selectivity was also investigated via cryogenic transmission electron microscopy (cryo-TEM) on dilute solutions. On the basis of the morphology of the dilute solution copolymer aggregate structures in the ionic liquid solvents, and on the structural length scales of the concentrated solutions, it was concluded that for PB-PEO [BMI][PF{sub 6}] behaves as a more selective solvent than [EMI][TFSI].

  9. Polymer stabilized liquid crystals: Topology-mediated electro-optical behavior and applications

    NASA Astrophysics Data System (ADS)

    Weng, Libo

    There has been a wide range of liquid crystal polymer composites that vary in polymer concentration from as little as 3 wt.% (polymer stabilized liquid crystal) to as high as 60 wt.% (polymer dispersed liquid crystals). In this dissertation, an approach of surface polymerization based on a low reactive monomer concentration about 1 wt.% is studied in various liquid crystal operation modes. The first part of dissertation describes the development of a vertical alignment (VA) mode with surface polymer stabilization, and the effects of structure-performance relationship of reactive monomers (RMs) and polymerization conditions on the electro-optical behaviors of the liquid crystal device has been explored. The polymer topography plays an important role in modifying and enhancing the electro-optical performance of stabilized liquid crystal alignment. The enabling surface-pinned polymer stabilized vertical alignment (PSVA) approach has led to the development of high-performance and fast-switching displays with controllable pretilt angle, increase in surface anchoring energy, high optical contrast and fast response time. The second part of the dissertation explores a PSVA mode with in-plane switching (IPS) and its application for high-efficiency and fast-switching phase gratings. The diffraction patterns and the electro-optical behaviors including diffraction efficiency and response time are characterized. The diffraction grating mechanism and performance have been validated by computer simulation. Finally, the advantages of surface polymerization approach such as good optical contrast and fast response time have been applied to the fringe-field switching (FFS) system. The concentration of reactive monomer on the electro-optical behavior of the FFS cells is optimized. The outstanding electro-optical results and mechanism of increase in surface anchoring strength are corroborated by the director field simulation. The density and topology of nanoscale polymer protrusions

  10. Fermi TGF detection map

    NASA Video Gallery

    Fermi’s Gamma-ray Burst Monitor detected 130 TGFs from August 2008 to the end of 2010. Thanks to instrument tweaks, the team has been able to improve the detection rate to several TGFs per week. ...

  11. Hydrodynamic Coulomb drag of strongly correlated electron liquids

    NASA Astrophysics Data System (ADS)

    Apostolov, S. S.; Levchenko, A.; Andreev, A. V.

    2014-03-01

    We develop a theory of Coulomb drag in ultraclean double layers with strongly correlated carriers. In the regime where the equilibration length of the electron liquid is shorter than the interlayer spacing the main contribution to the Coulomb drag arises from hydrodynamic density fluctuations. The latter consist of plasmons driven by fluctuating longitudinal stresses, and diffusive modes caused by temperature fluctuations and thermal expansion of the electron liquid. We express the drag resistivity in terms of the kinetic coefficients of the electron fluid. Our results are nonperturbative in interaction strength and do not assume Fermi-liquid behavior of the electron liquid.

  12. The critical behavior of the refractive index near liquid-liquid critical points.

    PubMed

    Losada-Pérez, Patricia; Glorieux, Christ; Thoen, Jan

    2012-04-14

    The nature of the critical behavior in the refractive index n is revisited in the framework of the complete scaling formulation. A comparison is made with the critical behavior of n as derived from the Lorentz-Lorenz equation. Analogue anomalies to those predicted for the dielectric constant ε, namely, a leading |t|(2β) singularity in the coexistence-curve diameter in the two-phase region and a |t|(1-α) along the critical isopleth in the one phase region, are expected in both cases. However, significant differences as regards the amplitudes of both singularities are obtained from the two approaches. Analysis of some literature data along coexistence in the two-phase region and along the critical isopleth in the one-phase region provide evidence of an intrinsic effect, independent of the density, in the critical anomalies of n. This effect is governed by the shift of the critical temperature with an electric field, which is supposed to take smaller values at optical frequencies than at low frequencies in the Hz to MHz range.

  13. Interaction quenches of Fermi gases

    SciTech Connect

    Uhrig, Goetz S.

    2009-12-15

    It is shown that the jump in the momentum distribution of Fermi gases evolves smoothly for small and intermediate times once an interaction between the fermions is suddenly switched on. The jump does not vanish abruptly. The loci in momentum space where the jumps occur are those of the noninteracting Fermi sea. No relaxation of the Fermi surface geometry takes place.

  14. Peculiar liquid-feeding and pathogen transmission behavior of Aedes togoi and comparison with Anopheles sinensis

    PubMed Central

    Lee, Sang Joon; Kang, Dooho; Lee, Seung Chul; Ha, Young-Ran

    2016-01-01

    Female mosquitoes transmit various diseases as vectors during liquid-feeding. Identifying the determinants of vector efficiency is a major scientific challenge in establishing strategies against these diseases. Infection rate and transmission efficiency are interconnected with the mosquito-induced liquid-feeding flow as main indexes of vector efficiency. However, the relationship between liquid-feeding characteristics and pathogen remains poorly understood. The liquid-feeding behavior of Aedes togoi and Anopheles sinensis was comparatively investigated in conjunction with vector efficiency via micro-particle image velocimetry. The flow rates and ratio of the ejection volume of Aedes togoi were markedly higher than those of Anophels sinensis. These differences would influence pathogen re-ingestion. Wall shear stresses of these mosquito species were also clearly discriminatory affecting the infective rates of vector-borne diseases. The variations in volume of two pump chambers and diameter of proboscis of these mosquito species were compared to determine the differences in the liquid-feeding process. Liquid-feeding characteristics influence vector efficiency; hence, this study can elucidate the vector efficiency of mosquitoes and the vector-pathogen interactions and contribute to the development of strategies against vector-borne diseases. PMID:26839008

  15. Peculiar liquid-feeding and pathogen transmission behavior of Aedes togoi and comparison with Anopheles sinensis.

    PubMed

    Lee, Sang Joon; Kang, Dooho; Lee, Seung Chul; Ha, Young-Ran

    2016-01-01

    Female mosquitoes transmit various diseases as vectors during liquid-feeding. Identifying the determinants of vector efficiency is a major scientific challenge in establishing strategies against these diseases. Infection rate and transmission efficiency are interconnected with the mosquito-induced liquid-feeding flow as main indexes of vector efficiency. However, the relationship between liquid-feeding characteristics and pathogen remains poorly understood. The liquid-feeding behavior of Aedes togoi and Anopheles sinensis was comparatively investigated in conjunction with vector efficiency via micro-particle image velocimetry. The flow rates and ratio of the ejection volume of Aedes togoi were markedly higher than those of Anophels sinensis. These differences would influence pathogen re-ingestion. Wall shear stresses of these mosquito species were also clearly discriminatory affecting the infective rates of vector-borne diseases. The variations in volume of two pump chambers and diameter of proboscis of these mosquito species were compared to determine the differences in the liquid-feeding process. Liquid-feeding characteristics influence vector efficiency; hence, this study can elucidate the vector efficiency of mosquitoes and the vector-pathogen interactions and contribute to the development of strategies against vector-borne diseases. PMID:26839008

  16. Peculiar liquid-feeding and pathogen transmission behavior of Aedes togoi and comparison with Anopheles sinensis

    NASA Astrophysics Data System (ADS)

    Lee, Sang Joon; Kang, Dooho; Lee, Seung Chul; Ha, Young-Ran

    2016-02-01

    Female mosquitoes transmit various diseases as vectors during liquid-feeding. Identifying the determinants of vector efficiency is a major scientific challenge in establishing strategies against these diseases. Infection rate and transmission efficiency are interconnected with the mosquito-induced liquid-feeding flow as main indexes of vector efficiency. However, the relationship between liquid-feeding characteristics and pathogen remains poorly understood. The liquid-feeding behavior of Aedes togoi and Anopheles sinensis was comparatively investigated in conjunction with vector efficiency via micro-particle image velocimetry. The flow rates and ratio of the ejection volume of Aedes togoi were markedly higher than those of Anophels sinensis. These differences would influence pathogen re-ingestion. Wall shear stresses of these mosquito species were also clearly discriminatory affecting the infective rates of vector-borne diseases. The variations in volume of two pump chambers and diameter of proboscis of these mosquito species were compared to determine the differences in the liquid-feeding process. Liquid-feeding characteristics influence vector efficiency; hence, this study can elucidate the vector efficiency of mosquitoes and the vector-pathogen interactions and contribute to the development of strategies against vector-borne diseases.

  17. Bifurcation analysis of the behavior of partially wetting liquids on a rotating cylinder

    NASA Astrophysics Data System (ADS)

    Lin, Te-Sheng; Rogers, Steven; Tseluiko, Dmitri; Thiele, Uwe

    2016-08-01

    We discuss the behavior of partially wetting liquids on a rotating cylinder using a model that takes into account the effects of gravity, viscosity, rotation, surface tension, and wettability. Such a system can be considered as a prototype for many other systems where the interplay of spatial heterogeneity and a lateral driving force in the proximity of a first- or second-order phase transition results in intricate behavior. So does a partially wetting drop on a rotating cylinder undergo a depinning transition as the rotation speed is increased, whereas for ideally wetting liquids, the behavior only changes quantitatively. We analyze the bifurcations that occur when the rotation speed is increased for several values of the equilibrium contact angle of the partially wetting liquids. This allows us to discuss how the entire bifurcation structure and the flow behavior it encodes change with changing wettability. We employ various numerical continuation techniques that allow us to track stable/unstable steady and time-periodic film and drop thickness profiles. We support our findings by time-dependent numerical simulations and asymptotic analyses of steady and time-periodic profiles for large rotation numbers.

  18. Mott Criticality and Pseudogap in Bose-Fermi Mixtures

    NASA Astrophysics Data System (ADS)

    Altman, Ehud; Demler, Eugene; Rosch, Achim

    2012-12-01

    We study the Mott transition of a mixed Bose-Fermi system of ultracold atoms in an optical lattice, where the number of (spinless) fermions and bosons adds up to one atom per lattice, nF+nB=1. For weak interactions, a Fermi surface coexists with a Bose-Einstein condensate while for strong interaction the system is incompressible but still characterized by a Fermi surface of composite fermions. At the critical point, the spectral function of the fermions A(k,ω) exhibits a pseudogapped behavior, rising as |ω| at the Fermi momentum, while in the Mott phase it is fully gapped. Taking into account the interaction between the critical modes leads at very low temperatures either to p-wave pairing or the transition is driven weakly first order. The same mechanism should also be important in antiferromagnetic metals with a small Fermi surface.

  19. Polarized and depolarized Raman spectra of liquid carbon disulfide in the pressure range 0-10 kbar. I. Vibration frequencies, C-S bond length, and Fermi resonance

    NASA Astrophysics Data System (ADS)

    Ikawa, S.; Whalley, Edward

    1986-09-01

    The effect of pressure on the polarized and depolarized Raman spectra of liquid carbon disulphide, i.e., the peak frequencies, bandwidths, and relative intensities of both the allowed ν1 and 2ν2 bands and the interaction-induced ν2 and ν3 bands, have been measured at 22 °C up to 10 kbar. This paper discusses the effect of pressure on the frequencies and on the relative isotropic intensity of the ν1 and 2ν2 bands. The frequency of the ν1 band increases linearly with pressure, within the experimental uncertainty, at the rate 0.16±0.01 cm-1 kbar-1, and the frequencies of the ν2, ν3, and 2ν2 bands decrease nonlinearly. The frequency shifts are described by second-order perturbation theory with the molecular anharmonicity and the intermolecular interaction as perturbations. The leading terms of the shifts consist of the same derivative of the interaction potential, multiplied by different anharmonicity constants, and the shifts of the ν1 and 2ν2 bands suggests that the C-S bond length decreases at the rate 2×10-4 Å kbar-1. The relative isotropic intensity of the 2ν2 and ν1 bands increases with pressure at the rate 0.050 kbar-1, whereas the anisotropic 2ν2 intensity relative to the isotropic ν1 intensity is independent of pressure to the experimental precision of ˜0.005. The effect of pressure on the second derivative of the isotropic and anisotropic parts of the polarizability with respect to the bend coordinate was estimated as 1.1×10-43 C m2 V-1 kbar-1 and ˜0, respectively, from these values.

  20. Liquid Fuels: Pyrolytic Degradation and Fire Spread Behavior as Influenced by Buoyancy

    NASA Technical Reports Server (NTRS)

    Ross, Howard D. (Technical Monitor); Yeboah, Yaw D.

    2003-01-01

    This project was conducted by the Combustion and Emission Control Lab in the Engineering Department at Clark Atlanta University under NASA Grant No. NCC3-707. The work aimed at providing data to supplement the ongoing NASA research activities on flame spread across liquid pools by providing flow visualization and velocity measurements especially in the gas phase and gas-liquid interface. During this investigation, the detailed physics of flame spread across liquid pools was revealed using particle image velocimetry (PIV), 3-dimensional Laser Doppler velocimetry (LDV) and high-speed video imaging system (HSVS). Flow fields (front and side views) of both the liquid and gas phases were visually investigated for the three subflash regimes of flame spread behavior. Some interesting findings obtained from the front and side views on flame spread across butanol pools are presented. PIV results showed the size of the transient vortex in the liquid phase near the flame front varied with the initial pool temperature. The transient vortex ahead of the flame front in the gas phase was, for the first time, clearly observed located just within 0-3 mm above the liquid surface and its size was dependent on the initial pool temperature. We calculated the flow velocity at 1 mm below the liquid surface near the flame front and inferred the generation mechanism of the vortex in the gas phase. Finally, after comparison of the flow velocity of the liquid surface and the flame spread rate, a reasonable explanation to the formation mechanism of the pulsating characteristic was proposed. This explanation is compatible with the previous numerical calculations and deductions.

  1. Evaluation of liquid behavior in a Variable Conductance Heat Pipe by neutron radiography

    NASA Astrophysics Data System (ADS)

    Sugimoto, K.; Asano, H.; Murakawa, H.; Takenaka, N.; Nagayasu, T.; Ipposhi, S.

    2011-09-01

    A Variable Conductance Heat Pipe (VCHP) is used as a cooling device for electrical equipments. The condensation area is passively controlled by the non-condensable gas volume in the VCHP depending on the heat load. The VCHP has often a bent pipe between the evaporation and condensation area. The heat pipe performance depends much on the bent pipe shape and configuration because a liquid plug is formed in the bent pipe and disturbs the refrigerant circulation. However, the mechanism has not been clarified well. The neutron radiography system at the JRR-3 in Japan Atomic Energy Agency (JAEA) was used to visualize the refrigerant behavior in the VCHP. Effects of the thin plate inserted in the pipe, refrigerant filling ratios and heat pipe configuration were examined on the heat pipe performance. The liquid plug was formed at the bend and caused to decrease the performance. It was confirmed that the thin plate insert was effective to disturb the liquid plug formation.

  2. Aggregation behavior and total miscibility of fluorinated ionic liquids in water.

    PubMed

    Pereiro, Ana B; Araújo, João M M; Teixeira, Fabiana S; Marrucho, Isabel M; Piñeiro, Manuel M; Rebelo, Luis Paulo N

    2015-02-01

    In this work, novel and nontoxic fluorinated ionic liquids (FILs) that are totally miscible in water and could be used in biological applications, where fluorocarbon compounds present a handicap because their aqueous solubility (water and biological fluids) is in most cases too low, have been investigated. The self-aggregation behavior of perfluorosulfonate-functionalized ionic liquids in aqueous solutions has been characterized using conductometric titration, isothermal titration calorimetry (ITC), surface tension measurements, dynamic light scattering (DLS), viscosity and density measurements, and transmission electron microscopy (TEM). Aggregation and interfacial parameters have been computed by conductimetry, calorimetry, and surface tension measurements in order to study various thermodynamic and surface properties that demonstrate that the aggregation process is entropy-driven and that the aggregation process is less spontaneous than the adsorption process. The novel perfluorosulfonate-functionalized ILs studied in this work show improved surface activity and aggregation behavior, forming distinct self-assembled structures.

  3. Observation of Fractional Stokes-Einstein Behavior in the Simplest Hydrogen-bonded Liquid

    SciTech Connect

    Herwig, Kenneth W; Molaison, Jamie J; Fernandez-Alonso, F.; Bermejo, F. J.; Turner, John F. C.; McLain, Sylvia E.

    2007-01-01

    Quasielastic neutron scattering has been used to investigate the single-particle dynamics of hydrogen fluoride across its entire liquid range at ambient pressure. For T > 230 K, translational diffusion obeys the celebrated Stokes-Einstein relation, in agreement with nuclear magnetic resonance studies. At lower temperatures, we find significant deviations from the above behavior in the form of a power law with exponent xi = -0.71+/-0.05. More striking than the above is a complete breakdown of the Debye-Stokes-Einstein relation for rotational diffusion. Our findings provide the first experimental verification of fractional Stokes-Einstein behavior in a hydrogen-bonded liquid, in agreement with recent computer simulations.

  4. Numerical simulation of solid liquid interface behavior during continuous strip casting process.

    PubMed

    Lee, Changbum; Yoon, Wooyoung; Shin, Seungwon; Lee, Jaewoo; Jang, Bo-Yun; Kim, Joonsoo; Ahn, Youngsoo; Lee, Jinseok

    2013-05-01

    A new metal-strip-casting process called continuous strip-casting (CSC) has been developed for making thin metal strips. A numerical simulation model to help understand solid-liquid interface behavior during CSC has been developed and used to identify the solidification morphologies of the strips and to determine the optimum processing conditions. In this study, we used a modified level contour reconstruction method (LCRM) and the sharp interface method to modify interface tracking, and performed a simulation analysis of the CSC process. The effects of process parameters such as heat-transfer coefficient and extrusion velocity on the behavior of the solid-liquid interface were estimated and used to improve the apparatus. A Sn (Tin) plate of dimensions 200 x 50 x 1 mm3 was successfully produced by CSC for a heat-transfer coefficient of 104 W/m2 K and an extrusion velocity of 0.2 m/s.

  5. Behavior of supercooled aqueous solutions stemming from hidden liquid–liquid transition in water

    SciTech Connect

    Biddle, John W.; Holten, Vincent; Anisimov, Mikhail A.

    2014-08-21

    A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid–liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid–liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two systems, H{sub 2}O-NaCl and H{sub 2}O-glycerol. We find the behavior of the heat capacity in supercooled aqueous solutions of NaCl, as reported by Archer and Carter [J. Phys. Chem. B 104, 8563 (2000)], to be consistent with the presence of the metastable liquid–liquid transition. We elucidate the non-conserved nature of the order parameter (extent of “reaction” between two alternative structures of water) and the consequences of its coupling with conserved properties (density and concentration). We also show how the shape of the critical line in a solution controls the difference in concentration of the coexisting liquid phases.

  6. Behavior of ceramic particles at the solid-liquid metal interface in metal matrix composites

    NASA Technical Reports Server (NTRS)

    Stefanescu, D. M.; Dhindaw, B. K.; Kacar, S. A.; Moitra, A.

    1988-01-01

    Directional solidification results were obtained in order to investigate particle behavior at the solid-liquid interface in Al-2 pct Mg (cellular interface) and Al-6.1 pct Ni (eutectic interface) alloys. It is found that particles can be entrapped in the solid if adequate solidification rates and temperature gradients are used. Model results showed critical velocity values slightly higher than those obtained experimentally.

  7. The Connection Between Local Icosahedral Order in Metallic Liquids and the Nucleation Behavior of Ordered Phases

    NASA Technical Reports Server (NTRS)

    Kelton, K. F.; Gangopadhyay, A. K.; Lee, G. W.; Hyers, R. W.; Rathz, T. J.; Rogers, J. R.; Robinson, M. B.; Schenk, T.; Simonet, V.

    2003-01-01

    Over fifty years ago, David Turnbull showed that the temperature of many metallic liquids could be decreased far below their equilibrium melting temperature before crystallization occurred. To explain those surprising results, Charles Frank hypothesized that the local structures of undercooled metallic liquids are different from those of crystal phases, containing a significant degree of icosahedral order that is incompatible with extended periodicity. Such structural differences must create a barrier to the formation crystal phases, explaining the observed undercooling behavior. If true, the nucleation from the liquid of phases with extended icosahedral order should be easier. Icosahedral order is often favored in small clusters, as observed recently in liquid-like clusters of pure Pb on the (111) surface of Si[3], for example. However, it has never been shown that an increasing preference for icosahedral phase formation can be directly linked with the development of icosahedral order in the undercooled liquid. Owing to the combination of very recent advances in levitation techniques and the availability of synchrotron x-ray and high flux neutron facilities, this is shown here.

  8. Free Expansion of a Weakly-Interacting Dipolar Fermi Gas

    NASA Astrophysics Data System (ADS)

    Takushi Nishimura,; Tomoyuki Maruyama,

    2010-08-01

    We theoretically investigate a polarized dipolar Fermi gas in free expansion. The inter-particle dipolar interaction deforms phase-space distribution in trap and also in the expansion. We exactly predict the minimal quadrupole deformation in the expansion for the high-temperature Maxwell-Boltzmann and zero-temperature Thomas-Fermi gases in the Hartree-Fock and Landau-Vlasov approaches. In conclusion, we provide a proper approach to develop the time-of-flight method for the weakly-interacting dipolar Fermi gas and also reveal a scaling law associated with the Liouville’s theorem in the long-time behaviors of the both gases.

  9. Spin density wave order, topological order, and Fermi surface reconstruction

    NASA Astrophysics Data System (ADS)

    Sachdev, Subir; Berg, Erez; Chatterjee, Shubhayu; Schattner, Yoni

    2016-09-01

    In the conventional theory of density wave ordering in metals, the onset of spin density wave (SDW) order coincides with the reconstruction of the Fermi surfaces into small "pockets." We present models which display this transition, while also displaying an alternative route between these phases via an intermediate phase with topological order, no broken symmetry, and pocket Fermi surfaces. The models involve coupling emergent gauge fields to a fractionalized SDW order, but retain the canonical electron operator in the underlying Hamiltonian. We establish an intimate connection between the suppression of certain defects in the SDW order and the presence of Fermi surface sizes distinct from the Luttinger value in Fermi liquids. We discuss the relevance of such models to the physics of the hole-doped cuprates near optimal doping.

  10. Radio-Frequency Spectroscopy of strongly interacting Fermi gases

    NASA Astrophysics Data System (ADS)

    Schirotzek, Andre; Wu, Cheng-Hsun; Sommer, Ariel; Zwierlein, Martin

    2009-05-01

    Strongly interacting Fermi gases exhibit a rich phase diagram in the BEC-BCS crossover. In recent experiments we have used radio frequency spectroscopy to probe two physically very different regimes: 1.) We have observed Spin-Polarons in a highly imbalanced Fermi mixture. A single spin down atom immersed in a spin up Fermi sea dresses itself with a cloud of majority atoms, thus forming a Spin-Polaron. rf spectroscopy can directly reveal the polaron and allows for an experimental measure of the quasiparticle residue Z and the chemical potential μ of this Fermi liquid. At a critical interaction strength, the transition to two-particle molecular binding is observed. 2.) rf spectroscopy of quasiparticles in a polarized superfluid allowed us to determine the superfluid gap δ and has demonstrated the importance of the Hartree energy U in rf spectra [1]. [1] Andre Schirotzek, Yong-il Shin, Christian H. Schunck and Wolfgang Ketterle, Phys. Rev. Lett. 101, 140403 (2008)

  11. Theory of ultracold atomic Fermi gases

    SciTech Connect

    Giorgini, Stefano; Pitaevskii, Lev P.; Stringari, Sandro

    2008-10-15

    The physics of quantum degenerate atomic Fermi gases in uniform as well as in harmonically trapped configurations is reviewed from a theoretical perspective. Emphasis is given to the effect of interactions that play a crucial role, bringing the gas into a superfluid phase at low temperature. In these dilute systems, interactions are characterized by a single parameter, the s-wave scattering length, whose value can be tuned using an external magnetic field near a broad Feshbach resonance. The BCS limit of ordinary Fermi superfluidity, the Bose-Einstein condensation (BEC) of dimers, and the unitary limit of large scattering length are important regimes exhibited by interacting Fermi gases. In particular, the BEC and the unitary regimes are characterized by a high value of the superfluid critical temperature, on the order of the Fermi temperature. Different physical properties are discussed, including the density profiles and the energy of the ground-state configurations, the momentum distribution, the fraction of condensed pairs, collective oscillations and pair-breaking effects, the expansion of the gas, the main thermodynamic properties, the behavior in the presence of optical lattices, and the signatures of superfluidity, such as the existence of quantized vortices, the quenching of the moment of inertia, and the consequences of spin polarization. Various theoretical approaches are considered, ranging from the mean-field description of the BCS-BEC crossover to nonperturbative methods based on quantum Monte Carlo techniques. A major goal of the review is to compare theoretical predictions with available experimental results.

  12. Modeling the phase behavior in mixtures of pharmaceuticals with liquid or supercritical solvents.

    PubMed

    Tsivintzelis, Ioannis; Economou, Ioannis G; Kontogeorgis, Georgios M

    2009-05-01

    The concept of solubility parameter, which is widely used for the screening of solvents in pharmaceutical applications, is combined with a thermodynamic theory that is able to model systems with large deviations from ideal behavior. The nonrandom hydrogen-bonding (NRHB) theory is applied to model the phase behavior of mixtures of six pharmaceuticals (i.e., ibuprofen, ketoprofen, naproxen, benzoic acid, methyl paraben, and ethyl paraben). The pure fluid parameters of the studied pharmaceuticals were estimated using limited available experimental (or predicted) data on sublimation pressures, liquid densities, and Hansen's solubility parameters. The complex hydrogen-bonding behavior was explicitly accounted for, while the corresponding parameters were adopted from simpler molecules of similar chemical structure or/and fitted to the aforementioned pure fluid properties. In this way, the solubility of the studied pharmaceuticals in liquid solvents was calculated. The average root-mean-square deviation between experimental and calculated solubilities is 0.190 and 0.037 in log(10) units for prediction (calculations without a binary interaction parameter adjustment) and for correlation (calculations using one binary interaction parameter fitted to experimental data), respectively. In addition, using one temperature-independent binary interaction parameter the phase behavior of pharmaceuticals in supercritical CO(2) and ethane was satisfactorily correlated. Finally, preliminary encouraging results are shown concerning two ternary mixtures where the model is able to predict accurately the solubility of pharmaceuticals in mixed solvents based on interaction parameters fitted to corresponding single solvent data. PMID:19368360

  13. Modeling the phase behavior in mixtures of pharmaceuticals with liquid or supercritical solvents.

    PubMed

    Tsivintzelis, Ioannis; Economou, Ioannis G; Kontogeorgis, Georgios M

    2009-05-01

    The concept of solubility parameter, which is widely used for the screening of solvents in pharmaceutical applications, is combined with a thermodynamic theory that is able to model systems with large deviations from ideal behavior. The nonrandom hydrogen-bonding (NRHB) theory is applied to model the phase behavior of mixtures of six pharmaceuticals (i.e., ibuprofen, ketoprofen, naproxen, benzoic acid, methyl paraben, and ethyl paraben). The pure fluid parameters of the studied pharmaceuticals were estimated using limited available experimental (or predicted) data on sublimation pressures, liquid densities, and Hansen's solubility parameters. The complex hydrogen-bonding behavior was explicitly accounted for, while the corresponding parameters were adopted from simpler molecules of similar chemical structure or/and fitted to the aforementioned pure fluid properties. In this way, the solubility of the studied pharmaceuticals in liquid solvents was calculated. The average root-mean-square deviation between experimental and calculated solubilities is 0.190 and 0.037 in log(10) units for prediction (calculations without a binary interaction parameter adjustment) and for correlation (calculations using one binary interaction parameter fitted to experimental data), respectively. In addition, using one temperature-independent binary interaction parameter the phase behavior of pharmaceuticals in supercritical CO(2) and ethane was satisfactorily correlated. Finally, preliminary encouraging results are shown concerning two ternary mixtures where the model is able to predict accurately the solubility of pharmaceuticals in mixed solvents based on interaction parameters fitted to corresponding single solvent data.

  14. The Influence of Silica Nanoparticles on Ionic Liquid Behavior: A Clear Difference between Adsorption and Confinement

    PubMed Central

    Wang, Yaxing; Li, Cheng; Guo, Xiaojing; Wu, Guozhong

    2013-01-01

    The phase behaviors of ionic liquids (ILs) confined in nanospace and adsorbed on outer surface of nanoparticles are expected to be different from those of the bulk. Anomalous phase behaviors of room temperature ionic liquid tributylhexadecylphosphonium bromide (P44416Br) confined in ordered mesoporous silica nanoparticles with average pore size 3.7 nm and adsorbed on outer surface of the same silica nanoparticles were reported. It was revealed that the melting points (Tm) of confined and adsorbed ILs depressed significantly in comparison with the bulk one. The Tm depressions for confined and adsorbed ILs are 8 °C and 14 °C, respectively. For comparison with the phase behavior of confined P44416Br, 1-butyl-3-methylimidazolium bromide (BmimBr) was entrapped within silica nanopores, we observed an enhancement of 50 °C in Tm under otherwise similar conditions. The XRD analysis indicates the formation of crystalline-like phase under confinement, in contrast to the amorphous phase in adsorbed IL. It was confirmed that the behavior of IL has clear difference. Moreover, the complex π-π stacking and H-bonding do not exist in the newly proposed phosphonium-based IL in comparison with the widely studied imidazolium-based IL. The opposite change in melting point of P44416Br@SiO2 and BmimBr@SiO2 indicates that the cationic species plays an important role in the variation of melting point. PMID:24145752

  15. ASSESSING THE LEACHING BEHAVIOR OF METALS FROM A MINERAL PROCESSING WASTE AS A FUNCTION OF LIQUID TO SOLID RATIO

    EPA Science Inventory

    A mineral processing waste was used to study the effect of liquid to solid ratio (L/S) on the leaching behavior of metals. Leaching tests in the form of column and batch studies were carried out to investigate liquid to solid ratios ranging from 0.7 to 50. Although the waste pa...

  16. Unique liquid crystal behavior in water of anionic fluorocarbon-hydrocarbon hybrid surfactants containing oxyethylene units.

    PubMed

    Sagisaka, Masanobu; Fujita, Yoshie; Shimizu, Yusuke; Osanai, Chie; Yoshizawa, Atsushi

    2011-05-15

    This study reports the unique aqueous lyotropic liquid crystal behavior of an anionic hybrid surfactant, 8F-B2ES, which has 2-[2-(butyloxy)ethyloxy]ethyl and 1H,1H,2H,2H-perfluorodecyl tails. An 8F-B2ES-analog hybrid surfactant with no oxyethylene units (8F-DeS) and a symmetric fluorinated double-tail surfactant with two 2-(1H,1H,2H,2H-perfluorohexyloxy)ethyl tails (4FEOS) were used as control surfactants in examining the effects of the oxyethylene units and of the hybrid structure on the liquid crystal behavior. Polarized microscopic observations showed the formation of a lamellar liquid crystal phase for each surfactant/water mixture at surfactant concentrations higher than 10 wt.%. In the case of the 30 wt.% 8F-B2ES/water mixture, two types of spherical aggregates were observed at temperatures higher than 40 °C: one was a typical lamella liquid crystal with a maltese cross-texture, and the other was optically isotropic. Interestingly, when the 8F-B2ES lamellar phase was cooled to below 40 °C, the lamellar aggregates were distorted and the isotropic droplets became anisotropic. As this unique liquid crystal behavior was not observed for aqueous mixtures of the control surfactants, the oxyethylene units in the hybridized hydrocarbon tail play an important role in the behavior. This study also examined the effect of the oxyethylene units on microenvironmental polarity in the hybrid surfactant bilayer via fluorescence spectral measurements of pyrene solubilized in each lamellar phase. The polarity of the 8F-B2ES bilayer at 70 °C was found to be that of a hydrocarbon surfactant lamellar phase, and increased gradually with decreasing temperature. The polarity became the same as that of hydrophilic spherical micelles below 40 °C, despite the presence of the lamellar aggregates. Since the polarity in the 8F-DeS bilayer was independent of temperature, and as low as that of a typical hydrocarbon surfactant bilayer, hydration of the 8F-B2ES oxyethylene units would

  17. Chromatographic behavior of small organic compounds in low-temperature high-performance liquid chromatography using liquid carbon dioxide as the mobile phase.

    PubMed

    Motono, Tomohiro; Nagai, Takashi; Kitagawa, Shinya; Ohtani, Hajime

    2015-07-01

    Low-temperature high-performance liquid chromatography, in which a loop injector, column, and detection cell were refrigerated at -35ºC, using liquid carbon dioxide as the mobile phase was developed. Small organic compounds (polyaromatic hydrocarbons, alkylbenzenes, and quinones) were separated by low-temperature high-performance liquid chromatography at temperatures from -35 to -5ºC. The combination of liquid carbon dioxide mobile phase with an octadecyl-silica (C18 ) column provided reversed phase mode separation, and a bare silica-gel column resulted in normal phase mode separation. In both the cases, nonlinear behavior at approximately -15ºC was found in the relationship between the temperature and the retention factors of the analytes (van't Hoff plots). In contrast to general trends in high-performance liquid chromatography, the decrease in temperature enhanced the separation efficiency of both the columns.

  18. GRB Studies with Fermi

    NASA Technical Reports Server (NTRS)

    Meegan, Charles A.

    2008-01-01

    This slide presentation reviews the studies of Gamma Ray Bursts (GRB) with the Fermi Gamma Ray Space Telescope. Included are pictures of the observatory, with illustrations of the Large Area Telescope (LAT), and the Gamma-ray Burst Monitor (GBM) including information about both their capabilities. Graphs showing the GBM count rate over time after the GBM trigger for three GRBs, preliminary charts showing the multiple detector light curves the spectroscopy of the main LAT peak and the spectral evolution of GRB 080916C Burst Temporally-extended LAT emission.

  19. Effect of throttling on interface behavior and liquid residuals in weightlessness. [in flat-bottomed tank

    NASA Technical Reports Server (NTRS)

    Symons, E. P.

    1974-01-01

    An experimental investigation was conducted to study liquid-vapor interface behavior and subsequent vapor ingestion in a flat-bottomed cylindrical tank following a single-step throttling in outflow rate in a weightless environment. A throttling process in which the final Weber number was one-tenth of the initial Weber number tended to excite large-amplitude symmetric slosh, with the amplitude generally increasing as initial Weber number increased. As expected, liquid residuals were lower than those obtained without throttling and, for moderate values of initial Weber number, could be adequately predicted by assuming that all draining took place at the final Weber number. At large values of Weber number, residuals tended to be lower than this predicted value.

  20. On the behavior and stability of a liquid metal in quasi-planar electric contacts

    NASA Astrophysics Data System (ADS)

    Samuilov, S. D.

    2016-06-01

    The contacts between conductors formed under relatively low pressures can be treated as quasi-planar. Melting of the material of such contacts upon the passage of electric current is used in some technological processes, but the behavior of liquid in these conditions has not been analyzed. In this study, such an estimate was obtained for specific conditions appearing under electric-pulse compacting (briquetting) of metal shavings. Analysis of derived relations shows that this estimate is valid for any quasi-2D contacts upon passage of a pulsed current of duration from microseconds to milliseconds. It is shown that the spacing between contact surfaces decreases, the liquid metal is extruded in the lateral directions, and the area of the contact and its conductivity increase. Sausage-type magnetohydrodynamic (MHD) instability and overheating instability do not evolve in these conditions because the instability wavelength is larger than the rated thickness of the molten layer; screw MHD instability can appear in slower processes.

  1. Effect of Enantiomeric Excess on the Phase Behavior of Antiferroelectric Liquid Crystals

    SciTech Connect

    L Pan; B McCoy; S Wang; Z Liu; S Wang; R Pindak; C Huang

    2011-12-31

    Null transmission ellipsometry and resonant x-ray diffraction are employed to study the effect of enantiomeric excess (EE) on the phase behavior of antiferroelectric liquid crystal 10OTBBB1M7. Phase sequence, layer spacing, and pitch of the helical structures of the smectic-C*{sub {alpha}} and smectic-C* phases are studied as a function of temperature and EE. Upon reducing EE, a liquid-gas-type critical point of the smectic-C*{sub {alpha}} to smectic-C* transition is observed, as well as the disappearance of the smectic-C*{sub d4} and the smectic-C*{sub d3} phases. Results are analyzed in a mean-field model.

  2. Thermodynamics and Phase Behavior of Phosphonated Block Copolymers Containing Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Jung, Ha Young; Park, Moon Jeong

    Charge-containing copolymers have drawn intensive attention in recent years for their uses in wide range of electrochemical devices such as fuel cells, lithium batteries and actuators. Particularly, the creation of microphase-separated morphologies in such materials by designing them in block and graft configurations has been the subject of extensive studies, in order to establish a synergistic means of optimizing ion transport properties and mechanical integrity. Interest in this topic has been further stimulated by intriguing phase behavior from charge-containing polymers, which was not projected from conventional phase diagrams of non-ionic polymers. Herein, we investigate thermodynamics and phase behavior of a set of phosphonated block copolymers. By synthesizing low-molecular weight samples with degree of polymerization (N) <35, we observed order-disorder transition that enabled us to estimate effective Flory-Huggins interaction parameters (χ) by using random phase approximation. We further examined the systems by adding various ionic liquids, where noticeable increases in χ values and modulated microphase separation behavior were observed. The morphology-conductivity relationship has been elucidated by taking into account the segmental motion of polymer chains, volume of conducting phases, and the molecular interactions between phosphonated polymer chains and cations of ionic liquids.

  3. Phase behavior of chromonic liquid crystal mixtures of Sunset Yellow and Disodium Cromoglycate

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Akihiro; Smith, Gregory; Yi, Youngwoo; Xu, Charles; Biffi, Silvia; Serra, Francesca; Bellini, Tommaso; Clark, Noel

    2014-03-01

    Chromonic liquid crystals (CLCs) are formed when planar molecules dissolved in water stack into rod-like aggregates that can order as liquid crystals. Isotropic, nematic, and M-phases can be observed depending on the degree of molecular orientational and positional order by variation of the CLC concentration. We focused on mixtures of two well-known CLCs, Sunset Yellow, a food dye, and disodium cromoglycate (DSCG), an asthma medication. In order to study the phase behaviors of these mixtures, we observed their textures in glass cells and capillaries using polarized light microscopy. We report here a ternary phase diagram describing the complete phase behavior of the CLC mixtures. We observed a variety of phase behaviors depending on species ratio and concentration. In the isotropic phase, no clear phase separation of the two dyes was observed, while separation did occur in many nematic and M-phase combinations. We will also describe phase observations made using a light spectroscopy and bulk centrifugal partitioning. Grant support: NSF DMR 1207606 and NSF MRSEC DMR-0820579.

  4. Column liquid chromatography-ultraviolet and column liquid chromatography/mass spectrometry evaluation of stress degradation behavior of escitalopram oxalate.

    PubMed

    Dhaneshwar, Sunil R; Mahadik, Mahadeo V; Kulkarni, Mahesh J

    2009-01-01

    The objective of this work was to study the degradation behavior of escitalopram oxalate under different International Conference on Harmonization (ICH)-recommended stress conditions by column liquid chromatography (LC)-UV and LC/mass spectrometry (LC/MS) and to establish a validated stability-indicating LC assay method. Escitalopram oxalate was subjected to stress conditions of hydrolysis, oxidation, photolysis, and thermal decomposition. Extensive degradation was found to occur in alkaline medium. Mild degradation was observed in acidic and oxidative conditions. Escitalopram oxalate was stable to neutral, photolytic, and thermal stress. Successful separation of the drug from degradation products formed under stress conditions was achieved on a PerfectSil-100 ODS-3 column [C18 (5 microm, 25 cm x 4.6 mm id)] using methanol-0.01 M acetate buffer pH 3.8 adjusted with acetic acid (45 + 55) as the mobile phase. The flow rate was 1 ml/min, and the detection wavelength was 239 nm. The method was validated according to ICH guidelines. Major degradation products formed in hydrolysis and oxidative conditions were isolated, and structural elucidation of degradation products was done by LCIMS and infrared spectrometry studies. The major hydrolysis degradation product was confirmed as 1-(3-dimethylaminopropyl)-1-(4-fluoro- phenyl)-1,3dihydroisobenzofuran-5-carboxylic acid, and the major oxidative degradation product was confirmed as 1-{[3-dimethylamino(oxide)- propyl]-1-(4-fluro-phenyl)}-1,3-dihydro-isobenzofuran- 5-carbonitrile.

  5. Dielectric Behavior of Antiferroelectric Liquid Crystals in Presence of Flexoelectric Effect

    NASA Astrophysics Data System (ADS)

    Das, Deblal; Mandal, Pravash; Pal Majumder, Tapas

    2015-06-01

    We studied theoretically the effect of flexoelectricity on the behavior of dielectric fluctuations of antiferroelectric liquid crystals (AFLCs) influenced by the mechanical distortion associated with flexoelectric effect. By using the appropriate free energy and the Landau-Ginzburg equation, we found an approximate expression of dielectric permittivity, which was strongly influenced by the existence of flexoelectric polarization for both in-phase and anti-phase motions. Consequently, the corresponding dielectric strength for both in-phase and anti-phase motions were varied due to the existence of flexoelectric polarization.

  6. Nanoscale viscoplastic behavior of smectic liquid crystals and its application in nanolithography

    SciTech Connect

    Schulz, Benjamin Steffen, Paul Bahr, Christian

    2014-02-21

    We report a unique combination of properties of smectic liquid crystal films that can be described as a viscoplastic behavior on the nanoscale: On the one hand, the films preserve imprinted surface patterns despite being permeated by a directed molecular flow of the film material. On the other hand, their surface morphology can easily be manipulated using an atomic force microscopy tip. Our results demonstrate a controlled molecular-scale deposition of material on the film surface, thereby enabling nanolithographic surface modification of a fluid material.

  7. Conformal Fermi Coordinates

    SciTech Connect

    Dai, Liang; Pajer, Enrico; Schmidt, Fabian E-mail: Enrico.pajer@gmail.com

    2015-11-01

    Fermi Normal Coordinates (FNC) are a useful frame for isolating the locally observable, physical effects of a long-wavelength spacetime perturbation. Their cosmological application, however, is hampered by the fact that they are only valid on scales much smaller than the horizon. We introduce a generalization that we call Conformal Fermi Coordinates (CFC). CFC preserve all the advantages of FNC, but in addition are valid outside the horizon. They allow us to calculate the coupling of long- and short-wavelength modes on all scales larger than the sound horizon of the cosmological fluid, starting from the epoch of inflation until today, by removing the complications of the second order Einstein equations to a large extent, and eliminating all gauge ambiguities. As an application, we present a calculation of the effect of long-wavelength tensor modes on small scale density fluctuations. We recover previous results, but clarify the physical content of the individual contributions in terms of locally measurable effects and ''projection'' terms.

  8. Wilson Ratio of Fermi Gases in One Dimension

    NASA Astrophysics Data System (ADS)

    Guan, X.-W.; Yin, X.-G.; Foerster, A.; Batchelor, M. T.; Lee, C.-H.; Lin, H.-Q.

    2013-09-01

    We calculate the Wilson ratio of the one-dimensional Fermi gas with spin imbalance. The Wilson ratio of attractively interacting fermions is solely determined by the density stiffness and sound velocity of pairs and of excess fermions for the two-component Tomonaga-Luttinger liquid phase. The ratio exhibits anomalous enhancement at the two critical points due to the sudden change in the density of states. Despite a breakdown of the quasiparticle description in one dimension, two important features of the Fermi liquid are retained; namely, the specific heat is linearly proportional to temperature, whereas the susceptibility is independent of temperature. In contrast to the phenomenological Tomonaga-Luttinger liquid parameter, the Wilson ratio provides a powerful parameter for testing universal quantum liquids of interacting fermions in one, two, and three dimensions.

  9. [Systematic evaluation of retention behavior of carbohydrates in hydrophilic interaction liquid chromatography].

    PubMed

    Fu, Qing; Wang, Jun; Liang, Tu; Xu, Xiaoyong; Jin, Yu

    2013-11-01

    A systematic evaluation of retention behavior of carbohydrates in hydrophilic interaction liquid chromatography (HILIC) was performed. The influences of mobile phase, stationary phase and buffer salt on the retention of carbohydrates were investigated. According to the results, the retention time of carbohydrates decreased as the proportion of acetonitrile in mobile phase decreased. Increased time of carbohydrates was observed as the concentration of buffer salt in mobile phase increased. The retention behavior of carbohydrates was also affected by organic solvent and HILIC stationary phase. Furthermore, an appropriate retention equation was used in HILIC mode. The retention equation lnk = a + blnC(B) + cC(B) could quantitatively describe the retention factors of carbohydrates of plant origin with good accuracy: the relative error of the predicted time to actual time was less than 0.3%. The evaluation results could provide guidance for carbohydrates to optimize the experimental conditions in HILIC method development especially for carbohydrate separation

  10. Spin Gap and Luttinger Liquid Description of the NMR Relaxation in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Dóra, Balázs; Gulácsi, Miklós; Simon, Ferenc; Kuzmany, Hans

    2007-10-01

    Recent NMR experiments by Singer et al. [Singer , Phys. Rev. Lett. 95, 236403 (2005).PRLTAO0031-900710.1103/PhysRevLett.95.236403] showed a deviation from Fermi-liquid behavior in carbon nanotubes with an energy gap evident at low temperatures. Here, a comprehensive theory for the magnetic field and temperature dependent NMR C13 spin-lattice relaxation is given in the framework of the Tomonaga-Luttinger liquid. The low temperature properties are governed by a gapped relaxation due to a spin gap (˜30K), which crosses over smoothly to the Luttinger liquid behavior with increasing temperature.

  11. Gas-liquid phase coexistence and crossover behavior of binary ionic fluids with screened Coulomb interactions.

    PubMed

    Patsahan, O

    2014-06-01

    We study the effects of an interaction range on the gas-liquid phase diagram and the crossover behavior of a simple model of ionic fluids: an equimolar binary mixture of equisized hard spheres interacting through screened Coulomb potentials which are repulsive between particles of the same species and attractive between particles of different species. Using the collective variables theory, we find explicit expressions for the relevant coefficients of the effective φ{4} Ginzburg-Landau Hamiltonian in a one-loop approximation. Within the framework of this approximation, we calculate the critical parameters and gas-liquid phase diagrams for varying inverse screening length z. Both the critical temperature scaled by the Yukawa potential contact value and the critical density rapidly decrease with an increase of the interaction range (a decrease of z) and then for z<0.05 they slowly approach the values found for a restricted primitive model (RPM). We find that gas-liquid coexistence region reduces with an increase of z and completely vanishes at z≃2.78. Our results clearly show that an increase in the interaction range leads to a decrease of the crossover temperature. For z≃0.01, the crossover temperature is the same as for the RPM.

  12. Differential dynamic behaviors of undulatory nematodes in liquid vs. soft gel environment

    NASA Astrophysics Data System (ADS)

    Park, Jin-Sung; Shin, Jennifer H.

    2015-03-01

    Caenorhabditis elegans (C. elegans) is an undulatory nematode which exhibits two distinct locomotion types of swimming and crawling. Although in its natural habitat C. elegans lives in complex fluidic environment, our current understanding has been limited to the behavior of C. elegans in a simple Newtonian fluid. Here, we present some experimental results on the penetrating behavior of C. elegans at the interface from liquid to solid environment. Once C. elegans, which otherwise swims freely in a liquid, makes a contact to the solid gel boundary, it begins to penetrate vertically to the surface by changing its stroke motion characterized by a stiffer body shape and a slow stroke frequency. The particle image velocimetry (PIV) analysis reveals the flow streamlines produced by the stroke of worm. For the worm that crawls on a solid surface, we utilize a technique of traction force microscopy (TFM) to find that the crawling nematode forms localized force islands along the body where makes direct contacts to the gel surface. This work was supported by the National Research Foundation (NRF) Grant 2013R1A1A2012420 and 2010-0016886.

  13. The dynamic behavior of a liquid ethanol-water mixture: a perspective from quantum chemical topology.

    PubMed

    Mejía, Sol M; Mills, Matthew J L; Shaik, Majeed S; Mondragon, Fanor; Popelier, Paul L A

    2011-05-01

    Quantum Chemical Topology (QCT) is used to reveal the dynamics of atom-atom interactions in a liquid. A molecular dynamics simulation was carried out on an ethanol-water liquid mixture at its azeotropic concentration (X(ethanol)=0.899), using high-rank multipolar electrostatics. A thousand (ethanol)(9)-water heterodecamers, respecting the water-ethanol ratio of the azeotropic mixture, were extracted from the simulation. Ab initio electron densities were computed at the B3LYP/6-31+G(d) level for these molecular clusters. A video shows the dynamical behavior of a pattern of bond critical points and atomic interaction lines, fluctuating over 1 ns. A bond critical point distribution revealed the fluctuating behavior of water and ethanol molecules in terms of O-H···O, C-H···O and H···H interactions. Interestingly, the water molecule formed one to six C-H···O and one to four O-H···O interactions as a proton acceptor. We found that the more localized a dynamical bond critical point distribution, the higher the average electron density at its bond critical points. The formation of multiple C-H···O interactions affected the shape of the oxygen basin of the water molecule, which is shown in three dimensions. The hydrogen atoms of water strongly preferred to form H···H interactions with ethanol's alkyl hydrogen atoms over its hydroxyl hydrogen.

  14. Protonic Ammonium Nitrate Ionic Liquids and Their Mixtures: Insights into Their Thermophysical Behavior.

    PubMed

    Canongia Lopes, José N; Esperança, José M S S; de Ferro, André Mão; Pereiro, Ana B; Plechkova, Natalia V; Rebelo, Luis P N; Seddon, Kenneth R; Vázquez-Fernández, Isabel

    2016-03-10

    This study is centered on the thermophysical characterization of different families of alkylammonium nitrate ionic liquids and their binary mixtures, namely the determination at atmospheric pressure of densities, electric conductivities and viscosities in the 288.15 < T/K < 353.15 range. First, measurements focusing on ethylammonium, propylammonium and butylammonium nitrate systems, and their binary mixtures, were determined. These were followed by studies involving binary mixtures composed of ethylammonium nitrate (with three hydrogen bond donor groups) and different homologous ionic liquids with differing numbers of hydrogen bond donor groups: diethylammonium nitrate (two hydrogen bond donors), triethylammonium nitrate (one hydrogen bond donor) and tetraethylammonium nitrate (no hydrogen bond donors). Finally, the behavior of mixtures with different numbers of equivalent carbon atoms in the alkylammonium cations was analyzed. The results show a quasi-ideal behavior for all monoalkylammonium nitrate mixtures. In contrast, the other mixtures show deviations from ideality, namely when the difference in the number of carbon atoms present in the cations increases or the number of hydrogen bond donors present in the cation decreases. Overall, the results clearly show that, besides the length and distribution of alkyl chains present in a cation such as alkylammonium, there are other structural and interaction parameters that influence the thermophysical properties of both pure compounds and their mixtures.

  15. Strain-cycling fatigue behavior of ten structural metals tested in liquid helium (4 K), in liquid nitrogen (78 K), and in ambient air (300 K)

    NASA Technical Reports Server (NTRS)

    Nachtigall, A. J.

    1974-01-01

    Strain-cycling fatigue behavior of 10 different structural alloys and metals was investigated in liquid helium (4 K), in liquid nitrogen (78 K), and in ambient air (300 K). At high cyclic lives, fatigue resistance increased with decreasing temperature for all the materials investigated. At low cyclic lives, fatigue resistance generally decreased with decreasing temperature for the materials investigated. Only for Inconel 718 did fatigue resistance increase with decreasing temperature over the entire life range investigated. Comparison of the experimental fatigue behavior with that predicted by the Manson method of universal slopes showed that the fatigue behavior of these materials can be predicted for cryogenic temperatures by using material tensile properties obtained at those same temperatures.

  16. The electro-optical behavior of liquid crystal molecules on the surface of SiO2 inorganic thin films.

    PubMed

    Sung, Shi-Joon; Yang, Kee-Jeong; Kim, Dae-Hwan; Do, Yun Seon; Kang, Jin-Kyu; Choi, Byeong-Dae

    2009-12-01

    Inorganic thin films are well known for the liquid crystal alignment layers for LCoS application due to the higher thermal and photochemical stability of inorganic materials. The switching time of liquid crystals is the important factor for the projection application and the faster switching time is required for the high quality display. The switching behavior of liquid crystal molecules on inorganic thin films might be closely related with the surface properties of the inorganic thin films. Therefore the understanding of surface properties of the inorganic thin films is required for the enhancement of the switching time of liquid crystals of LCoS devices. In this work, we prepared the SiO2 inorganic thin films and the electro-optical behavior of liquid crystal molecules on SiO2 thin film was investigated. The sputtering condition of SiO2 thin film was closely related with the thickness and the surface morphology of SiO2 thin film. The switching time of liquid crystals with negative dielectric constant on SiO2 inorganic thin films was dominantly affected by the size of protrusion on the surface of SiO2 thin film and the surface roughness of SiO2 thin film was also related with the switching time of liquid crystals. From these results, it is possible to prepare the SiO2 inorganic thin film suitable for the liquid crystal alignment layer for VAN LC mode.

  17. The Characteristics, Behavior and Fate of a Stream of Liquid CO2 Released Into the Ocean

    NASA Astrophysics Data System (ADS)

    Brewer, P. G.; Dunk, R. M.; Peltzer, E. T.

    2005-12-01

    With the recent discovery of three sites venting a stream of volcanically derived liquid CO2 from the seafloor, questions arise as to the chemical characteristics, physical behavior, and ultimate fate and impact of the vented flow of this fluid. We now have a great deal of information, and compelling images, of liquid CO2 behavior in the deep-sea, derived from small-scale experiments carried out to investigate possibilities of ocean sequestration of fossil fuel CO2. The critical point of CO2 occurs at 31.3°C and 738.9 dbar. Thus volcanically derived CO2 will begin its transit to the seafloor as a supercritical fluid and will acquire chemical signatures consistent with this as it progresses through the pore space. As it approaches the cooler sediments and the seafloor, it condenses to the highly immiscible liquid phase. CO2 is a very low viscosity, highly compressible, non-polar fluid, with a remarkable ability to dissolve other non-polar species. Thus the magmatic gases, He and H2, will tend to be strongly enriched in the CO2 phase. Equilibrium calculations may be carried out on this process with considerable accuracy, but the extent to which the plume reaches equilibrium with the surrounding pore fluids during transit is unknown. On venting to the seafloor, hydrodynamic instabilities quickly result in CO2 droplet formation with droplet diameters on a cm scale. At depths above ~2700m, liquid CO2 is less dense than seawater. Furthermore, liquid CO2 readily forms a Structure I hydrate, the phase boundary is well known, and in Pacific Ocean waters typically occurs at ~400m depth. Thus at all three vent sites discovered to date, (JADE hydrothermal site, Okinawa Trough 1335 to 1550m; Champagne vent site NW Eifuku, 1650m; Vailulu'u seamount, 940m) a rising plume of CO2 droplets is formed within the hydrate stability zone, and a thin hydrate skin forms on the ascending droplets. As the hydrate coated droplets rise through the water column, they dissolve at a rate of ~3

  18. Difference of spectral superbroadening behavior in Kerr-type and non-Kerr-type liquids pumped with ultrashort laser pulses.

    PubMed

    He, G S; Xu, G C; Cui, Y; Prasad, P N

    1993-08-20

    The spectral superbroadening behavior of forward coherent radiation from a 10-cm-long liquid-filled cell is investigated by using an ultrashort (∼0.5 ps) and intense (∼10 GW/cm(2)) laser pulse as the pump source. Five different transparent liquids (heavy water, water, carbon tetrachloride, benzene, and carbon disulfide) have been studied with a special experimental design that can distinguish the predominant contributions from the various possible mechanisms. Under the same pump condition, a very wide and symmetrical superbroadening (continuum) is observed on both the Stokes and the anti-Stokes side of the pump line for non-Kerr-type liquids such as heavy water and water, whereas only a red-shifted spectral broadening can be observed on the Stokes side for Kerr-type liquids such as carbon disulfide and benzene. For an explanation of the latter behavior, the dominant contributions from stimulated Rayleigh-Kerr and Raman-Kerr scattering are proposed.

  19. Deliberate modification of the behavior of n-type cadium telluride/electrolyte interfaces by surface etching: Removal of fermi level pinning

    NASA Astrophysics Data System (ADS)

    Tanaka, S.; Bruce, J. A.; Wrighton, M. S.

    1981-09-01

    Single crystal, n-type CdTe (E sub g = 1.4 eV) has been studied with respect to barrier height, E sub B, when contacting a liquid electrolyte solution containing a fast, one-electron, outer-sphere redox reagent. We approximate E sub B as equal to the photovoltage measured by cyclic voltammetry of various redox couples at illuminated n-CdTe vs. a reversible electrode. N-CdTe surfaces pretreated with an oxidizing etch give an E sub B of approximately 0.5 V + or - 0.1 V in H2O/0.1 M NaClO4 or CH3CN/0.1 M (n-Bu4N)ClO4 that is independent of the E sub 1/2 of the added redox couple. A reducing etch pretreatment gives an E sub B in either of the electrolyte solutions that depends on E sub 1/2 of the redox couple in a manner consistent with a nearly ideal semiconductor. The reduced CdTe exhibits an E sub B of up to 0.9 V for a redox couple having E sub 1/2 near 0.0V vs. SCE, whereas couples having E sub 1/2 negative of approx. -1.0 V vs. SCE give zero photovoltage. Auger and X-ray photoelectron spectroscopy of the reduced and oxidized surfaces are qualitatively different. The reduced surface exhibits signals for Cd and Te in relative intensities that are consistent with a close to stoichiometric (1/1) surface. The oxidized surface exhibits little or no detectable Cd signal and the Te signal is consistent with a thick overlayer of elemental Te.

  20. Behavior of colloidal particles and micelles in thin liquid films with application to foam stability

    NASA Astrophysics Data System (ADS)

    Sethumadhavan, Gopi Nath

    Foams, emulsions and colloidal dispersions are frequently seen to occur in many industrial systems like ink, paint, milk, butter, shaving foams, etc. The key structural elements in these systems are the thin liquid films that form between the dispersed phase bubbles or droplets. Whenever two droplets or bubbles of different sizes come close together, the film formed between them is a curved film. Thus, experiments using surfactant-free, curved, single-foam-films containing colloidal particles were carried out to understand the effect of particle concentration, size, polydispersity, bidispersity and film size on the particle structuring phenomenon in the confined environment of a thin liquid film. Such layering provides additional stabilizing force and was also found to have a significant impact on the long-term stability of surfactant foams containing micelles. The work in this thesis using colloidal particles in curved films is the first of its kind. Experimentally it was observed that the particles moved from the film to the bulk in the process of reaching an equilibrium and the flux of particles from the film periphery was a constant. A critical film size was observed for the curved films below which the particles did not show a tendency to leave the film. At high particle concentrations, the particle movement from the film to the bulk was low. Polydispersed and bidispersed particles displayed high rates of particle exodus from the film to the bulk, which are indicative of poor particle structuring in the thin liquid films. Particle behavior in confinement was satisfactorily explained using the diffusive-osmotic model. Our preliminary studies also show that micelles with higher ability to form ordered layers in a confined environment display a higher pollutant removal efficiency from solid surfaces. Monte Carlo simulations of mono and bidispersed particles in thin liquid films corroborated the experimental observations. Particle layering was pronounced at high

  1. Liquid Fuels: Pyrolytic Degradation and Fire Spread Behavior as Influenced by Buoyancy

    NASA Technical Reports Server (NTRS)

    Yeboah, Yaw D.; Malbrue, Courtney; Savage, Melane; Liao, Bo; Ross, Howard D. (Technical Monitor)

    2001-01-01

    This work is being conducted by the Combustion and Emission Control Lab in the Engineering Department at Clark Atlanta University under NASA Grant No. NCC3-707. The work aims at providing data to supplement the ongoing NASA research activities on fire spread across liquid pools by providing flow visualization and velocity measurements especially in the gas phase and gas-liquid interface. The fabrication, installation, and testing were completed during this reporting period. The system shakedown and detailed quantitative measurements with High Speed Video and Particle Image Velocimetry (PIV) systems using butanol as fuel were performed. New and interesting results, not previously reported in the literature, were obtained from the experiments using a modified NASA tray and butanol as fuel. Three distinct flame spread regimes, as previously reported, were observed. These were the pseudo-uniform regime below 20 C, the pulsating regime between 22 and 30 C and the uniform regime above about 31 C. In the pulsating regime the jump velocity appeared to be independent of the pool temperature. However, the retreat velocity between jumps appeared to depend on the initial pool temperature. The flame retreated before surging forwards with increasing brightness. Previous literature reported this phenomenon only under microgravity conditions. However, we observed such behavior in our normal gravity experiments. Mini-pulsations behind the flame front were also observed. Two or three of these pulsations were observed within a single flame front pulsating time period. The velocity vector maps of the gas and liquid phases ahead, during, and behind the flame front were characterized. At least one recirculation cell was observed right below the flame front.The size of the liquid phase vortex (recirculation cell) below the flame front appeared to decrease with increasing initial pool temperature. The experiments also showed how multiple vortices developed in the liquid phase. A large

  2. The Statistical Fermi Paradox

    NASA Astrophysics Data System (ADS)

    Maccone, C.

    In this paper is provided the statistical generalization of the Fermi paradox. The statistics of habitable planets may be based on a set of ten (and possibly more) astrobiological requirements first pointed out by Stephen H. Dole in his book Habitable planets for man (1964). The statistical generalization of the original and by now too simplistic Dole equation is provided by replacing a product of ten positive numbers by the product of ten positive random variables. This is denoted the SEH, an acronym standing for “Statistical Equation for Habitables”. The proof in this paper is based on the Central Limit Theorem (CLT) of Statistics, stating that the sum of any number of independent random variables, each of which may be ARBITRARILY distributed, approaches a Gaussian (i.e. normal) random variable (Lyapunov form of the CLT). It is then shown that: 1. The new random variable NHab, yielding the number of habitables (i.e. habitable planets) in the Galaxy, follows the log- normal distribution. By construction, the mean value of this log-normal distribution is the total number of habitable planets as given by the statistical Dole equation. 2. The ten (or more) astrobiological factors are now positive random variables. The probability distribution of each random variable may be arbitrary. The CLT in the so-called Lyapunov or Lindeberg forms (that both do not assume the factors to be identically distributed) allows for that. In other words, the CLT "translates" into the SEH by allowing an arbitrary probability distribution for each factor. This is both astrobiologically realistic and useful for any further investigations. 3. By applying the SEH it is shown that the (average) distance between any two nearby habitable planets in the Galaxy may be shown to be inversely proportional to the cubic root of NHab. This distance is denoted by new random variable D. The relevant probability density function is derived, which was named the "Maccone distribution" by Paul Davies in

  3. The fermi paradox is neither Fermi's nor a paradox.

    PubMed

    Gray, Robert H

    2015-03-01

    The so-called Fermi paradox claims that if technological life existed anywhere else, we would see evidence of its visits to Earth--and since we do not, such life does not exist, or some special explanation is needed. Enrico Fermi, however, never published anything on this topic. On the one occasion he is known to have mentioned it, he asked "Where is everybody?"--apparently suggesting that we do not see extraterrestrials on Earth because interstellar travel may not be feasible, but not suggesting that intelligent extraterrestrial life does not exist or suggesting its absence is paradoxical. The claim "they are not here; therefore they do not exist" was first published by Michael Hart, claiming that interstellar travel and colonization of the Galaxy would be inevitable if intelligent extraterrestrial life existed, and taking its absence here as proof that it does not exist anywhere. The Fermi paradox appears to originate in Hart's argument, not Fermi's question. Clarifying the origin of these ideas is important, because the Fermi paradox is seen by some as an authoritative objection to searching for evidence of extraterrestrial intelligence--cited in the U.S. Congress as a reason for killing NASA's SETI program on one occasion. But evidence indicates that it misrepresents Fermi's views, misappropriates his authority, deprives the actual authors of credit, and is not a valid paradox. PMID:25719510

  4. The fermi paradox is neither Fermi's nor a paradox.

    PubMed

    Gray, Robert H

    2015-03-01

    The so-called Fermi paradox claims that if technological life existed anywhere else, we would see evidence of its visits to Earth--and since we do not, such life does not exist, or some special explanation is needed. Enrico Fermi, however, never published anything on this topic. On the one occasion he is known to have mentioned it, he asked "Where is everybody?"--apparently suggesting that we do not see extraterrestrials on Earth because interstellar travel may not be feasible, but not suggesting that intelligent extraterrestrial life does not exist or suggesting its absence is paradoxical. The claim "they are not here; therefore they do not exist" was first published by Michael Hart, claiming that interstellar travel and colonization of the Galaxy would be inevitable if intelligent extraterrestrial life existed, and taking its absence here as proof that it does not exist anywhere. The Fermi paradox appears to originate in Hart's argument, not Fermi's question. Clarifying the origin of these ideas is important, because the Fermi paradox is seen by some as an authoritative objection to searching for evidence of extraterrestrial intelligence--cited in the U.S. Congress as a reason for killing NASA's SETI program on one occasion. But evidence indicates that it misrepresents Fermi's views, misappropriates his authority, deprives the actual authors of credit, and is not a valid paradox.

  5. Low temperatures shear viscosity of a two-component dipolar Fermi gas with unequal population

    NASA Astrophysics Data System (ADS)

    Darsheshdar, E.; Yavari, H.; Zangeneh, Z.

    2016-07-01

    By using the Green's functions method and linear response theory we calculate the shear viscosity of a two-component dipolar Fermi gas with population imbalance (spin polarized) in the low temperatures limit. In the strong-coupling Bose-Einstein condensation (BEC) region where a Feshbach resonance gives rise to tightly bound dimer molecules, a spin-polarized Fermi superfluid reduces to a simple Bose-Fermi mixture of Bose-condensed dimers and the leftover unpaired fermions (atoms). The interactions between dimer-atom, dimer-dimer, and atom-atom take into account to the viscous relaxation time (τη) . By evaluating the self-energies in the ladder approximation we determine the relaxation times due to dimer-atom (τDA) , dimer-dimer (τcDD ,τdDD) , and atom-atom (τAA) interactions. We will show that relaxation rates due to these interactions τDA-1 ,τcDD-1, τdDD-1, and τAA-1 have T2, T4, e - E /kB T (E is the spectrum of the dimer atoms), and T 3 / 2 behavior respectively in the low temperature limit (T → 0) and consequently, the atom-atom interaction plays the dominant role in the shear viscosity in this rang of temperatures. For small polarization (τDA ,τAA ≫τcDD ,τdDD), the low temperatures shear viscosity is determined by contact interaction between dimers and the shear viscosity varies as T-5 which has the same behavior as the viscosity of other superfluid systems such as superfluid neutron stars, and liquid helium.

  6. Aggregation behavior of long-chain piperidinium ionic liquids in ethylammonium nitrate.

    PubMed

    Dai, Caili; Du, Mingyong; Liu, Yifei; Wang, Shilu; Zhao, Jianhui; Chen, Ang; Peng, Dongxu; Zhao, Mingwei

    2014-01-01

    Micelles formed by the long-chain piperidinium ionic liquids (ILs) N-alkyl-N-methylpiperidinium bromide of general formula CnPDB (n = 12, 14, 16) in ethylammonium nitrate (EAN) were investigated through surface tension and dissipative particle dynamics (DPD) simulations. Through surface tension measurements, the critical micelle concentration (cmc), the effectiveness of surface tension reduction (Πcmc), the maximum excess surface concentration (Гmax) and the minimum area occupied per surfactant molecule (Amin) can be obtained. A series of thermodynamic parameters (DG0 m, DH0 m and DS0 m) of micellization can be calculated and the results showed that the micellization was entropy-driven. In addition, the DPD simulation was performed to simulate the whole aggregation process behavior to better reveal the micelle formation process. PMID:25474288

  7. The self-associating behavior of NH3 and ND3 in liquid xenon

    NASA Astrophysics Data System (ADS)

    De Beuckeleer, Liene I.; Herrebout, Wouter A.

    2016-08-01

    In this study we report on the analysis of isothermal spectra of NH3 and ND3 solutions in liquid xenon at 203 K using newly developed and validated least-squares approaches to investigate the its self-associating behavior. For both species we observe clear dimer bands in the spectral area of the ν1+ν4, ν3+ν4 and ν1+ν2, ν3+ν2 combination bands. The analysis of the N-D stretching area, allows us to characterize clear contributions of dimers and trimers. The analysis of the Nsbnd H stretching area is hampered by the occurrence of a time dependent band due to solid water traces during the experiments. For NH3 we also performed an investigation of the Nsbnd H bending region, ν2, which demonstrated a small dimer absorption band. These obtained results compare well with literature data.

  8. Effect of dipolar interactions on the phase behavior of the Gay-Berne liquid crystal model

    NASA Astrophysics Data System (ADS)

    Houssa, Mohammed; Rull, Luis F.; McGrother, Simon C.

    1998-12-01

    A computer simulation study of the phase behavior of the dipolar Gay-Berne liquid crystal model is presented. The phase transitions are determined with isothermal-isobaric (NPT) Monte Carlo simulations, utilizing the reaction field method. The electrostatic forces are found to have a considerable effect on the nature of the observed phases, but the density at which the isotropic fluid becomes unstable with respect to partially ordered phases is seen to be remarkably insensitive to the strength of the dipole. We pay particular attention to the structure of the mesophases, combining information from several singlet and pair distribution functions to build up an accurate picture of the molecular arrangement of the systems.

  9. Long-time behavior of solution for the compressible nematic liquid crystal flows in R3

    NASA Astrophysics Data System (ADS)

    Gao, Jincheng; Tao, Qiang; Yao, Zheng-an

    2016-08-01

    In this paper, we investigate the global existence and long-time behavior of classical solution for the compressible nematic liquid crystal flows in three-dimensional whole space. First of all, the global existence of classical solution is established under the condition that the initial data are close to the constant equilibrium state in HN (R3) (N ≥ 3)-framework. Then, one establishes algebraic time decay for the classical solution by weighted energy method. Finally, the algebraic decay rate of classical solution in Lp (R3)-norm with 2 ≤ p ≤ ∞ and optimal decay rate of their spatial derivative in L2 (R3)-norm are obtained if the initial perturbation belong to L1 (R3) additionally.

  10. Dark solitons in a superfluid Fermi gas

    SciTech Connect

    Antezza, Mauro; Dalfovo, Franco; Stringari, Sandro; Pitaevskii, Lev P.

    2007-10-15

    We investigate the behavior of dark solitons in a superfluid Fermi gas along the BCS-BEC crossover by solving the Bogoliubov-de Gennes equations and looking for real and odd solutions for the order parameter. We show that in the resonance unitary region, where the scattering length is large, the density profile of the soliton has a deep minimum, differently from what happens in the BCS regime. The superfluid gap is found to be significantly quenched by the presence of the soliton due to the occurrence of Andreev fermionic bound states localized near the nodal plane of the order parameter.

  11. Quasicondensation in Two-Dimensional Fermi Gases.

    PubMed

    Wu, Chien-Te; Anderson, Brandon M; Boyack, Rufus; Levin, K

    2015-12-11

    In this paper we follow the analysis and protocols of recent experiments, combined with simple theory, to arrive at a physical understanding of quasi-condensation in two dimensional Fermi gases. A key signature of quasi-condensation, which contains aspects of Berezinskiĭ-Kosterlitz-Thouless behavior, is a strong zero momentum peak in the pair momentum distribution. Importantly, this peak emerges at a reasonably well defined onset temperature. The resulting phase diagram, pair momentum distribution, and algebraic power law decay are compatible with recent experiments throughout the continuum from BEC to BCS. PMID:26705613

  12. Fermi's New Pulsar Detection Technique

    NASA Video Gallery

    To locate a pulsar in Fermi LAT data requires knowledge of the object’s sky position, its pulse period, and how the pulse rate slows over time. Computers check many different combinations of posi...

  13. A field-space conformal-solution method: Binary vapor-liquid phase behavior

    NASA Astrophysics Data System (ADS)

    Storvick, T. S.; Fox, J. R.

    1990-01-01

    The field-space conformal solution method provides an entirely new thermodynamic framework for the description of fluid mixtures in terms of the properties of a pure reference fluid. The utility and performance of the method are examined in the special case of vapor-liquid equilibrium correlation for simple mixtures. This is one of several cases in which field-space methods have numerical or theoretical advantages over methods presently used in mixture property correlation; only properties along the vapor pressure curve of the purefluid reference system are required for a complete description of the mixture phase behavior. Vapor-liquid equilibrium data for three binary hydrocarbon mixtures, n-butane + n-pentane, n-butane + n-hexane, and n-butane + n-octane, are correlated with a simple implementation of the method having two independent mixture parameters. Two pure-fluid equations of state, a Peng-Robinson equation and a 32-constant modified Benedict-Webb-Rubin equation, are tested as reference systems. The effects of differences in the quality of the reference system and of a range of mixture component size ratios are examined.

  14. Characterization of preform permeability and flow behavior for liquid composite molding

    NASA Astrophysics Data System (ADS)

    Sommerlot, Stephen Joseph

    Preform characterization is an important step in the processing of high-performance parts with liquid composite molding. A better understanding of preform compressibility and permeability creates more accurate process models, ultimately leading to high-quality finished composites. Without characterization, mold design and processing parameters are subject to guess-work and ad hoc optimization methods, which can result in poor infusions and inconsistent part quality. In this study, a complex architecture fiber reinforcement was characterized in compaction and permeability for liquid composite molding. Preforms of a four-harness satin carbon fabric were assembled with and without a novel inter-layer tackifier for experimentation. Compaction and permeability were measured to investigate the effects of the tackifier system, debulking, preform layup, and other processing parameters. Permeability and flow behavior was measured through saturated and unsaturated techniques, including investigations of fluid effects and high-flow rate infusions. The tackifier was seen to decrease permeability in both saturated and unsaturated cases, while notably influencing the orientation of first principal permeability. Tackified preforms also displayed a sensitivity to fluid type that non-tackified samples did not. Experimentally derived permeability was also used to generate numerical mold fill simulations of radially injected infusions, which produced favorable results.

  15. Photocontrolled phase transitions and reflection behaviors of smectic liquid crystals by a chiral azobenzene.

    PubMed

    Guan, Jingjing; Zhang, Mingzhi; Li, Birong; Yang, Huai; Wang, Guojie

    2012-12-01

    The photocontrolled phase transitions and reflection behaviors of a smectic liquid crystal, 4-octyl-4'-cyanobiphenyl (8CB), tuned by a chiral azobenzene, are systematically investigated. For the smectic 8CB doped with the chiral azobenzene (1R)-(-)-4-n-hexyl-4'-menthylazobenzene (ABE), the initial smectic phase can be switched to cholesteric and then to isotropic upon UV irradiation due to the trans-to-cis photoisomerization of ABE; however, no reflection band is observed. For the smectic 8CB doped with ABE and the chiral agent (S)-(-)-1,1'-binaphthyl-2,2'-diol (BN), a reflection band located in the short-wavelength infrared region is observed, which disappears after further UV irradiation. For the smectic 8CB doped with ABE and a chiral agent with higher helical twisting power, (S)-2,2'-methylendioxy-1,1'-binaphthalene (DBN), a phototunable system with cholesteric pitch short enough to reflect visible light is demonstrated. With a given concentration of the chiral dopant DBN, a reversible reflection color transition is realized tuned by the isomerization of azobenzene. The reverse phase transition from isotropic to cholesteric and then to smectic can be recovered upon visible irradiation. The photocontrolled phase transitions in smectic liquid crystals and the corresponding changes in reflection band switched by photoisomerization of azobenzene may provide impetus for their practical application in optical memories, displays, and switches.

  16. Using Liquid Crystals to Reveal How Mechanical Anisotropy Changes Interfacial Behaviors of Motile Bacteria

    PubMed Central

    Mushenheim, Peter C.; Trivedi, Rishi R.; Weibel, Douglas B.; Abbott, Nicholas L.

    2014-01-01

    Bacteria often inhabit and exhibit distinct dynamical behaviors at interfaces, but the physical mechanisms by which interfaces cue bacteria are still poorly understood. In this work, we use interfaces formed between coexisting isotropic and liquid crystal (LC) phases to provide insight into how mechanical anisotropy and defects in LC ordering influence fundamental bacterial behaviors. Specifically, we measure the anisotropic elasticity of the LC to change fundamental behaviors of motile, rod-shaped Proteus mirabilis cells (3 μm in length) adsorbed to the LC interface, including the orientation, speed, and direction of motion of the cells (the cells follow the director of the LC at the interface), transient multicellular self-association, and dynamical escape from the interface. In this latter context, we measure motile bacteria to escape from the interfaces preferentially into the isotropic phase, consistent with the predicted effects of an elastic penalty associated with strain of the LC about the bacteria when escape occurs into the nematic phase. We also observe boojums (surface topological defects) present at the interfaces of droplets of nematic LC (tactoids) to play a central role in mediating the escape of motile bacteria from the LC interface. Whereas the bacteria escape the interface of nematic droplets via a mechanism that involved nematic director-guided motion through one of the two boojums, for isotropic droplets in a continuous nematic phase, the elasticity of the LC generally prevented single bacteria from escaping. Instead, assemblies of bacteria piled up at boojums and escape occurred through a cooperative, multicellular phenomenon. Overall, our studies show that the dynamical behaviors of motile bacteria at anisotropic LC interfaces can be understood within a conceptual framework that reflects the interplay of LC elasticity, surface-induced order, and topological defects. PMID:24988359

  17. Volovik effect and Fermi-liquid behavior in the s-wave superconductor CaPd2As2: As75 NMR-NQR measurements

    DOE PAGES

    Ding, Q. -P.; Wiecki, P.; Anand, V. K.; Sangeetha, N. S.; Lee, Y.; Johnston, D. C.; Furukawa, Y.

    2016-04-07

    The electronic and magnetic properties of the collapsed-tetragonal CaPd2As2 superconductor (SC) with a transition temperature of 1.27 K have been investigated by 75As nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements. The temperature (T) dependence of the nuclear spin lattice relaxation rates (1/T1) and the Knight shifts indicate the absence of magnetic correlations in the normal state. In the SC state, 1/T1 measured by 75As NQR shows a clear Hebel-Slichter (HS) peak just below Tc and decreases exponentially at lower T, confirming a conventional s-wave SC. Additionally, the Volovik effect, also known as the Doppler shift effect, hasmore » been clearly evidenced by the observation of the suppression of the HS peak with applied magnetic field.« less

  18. Fabrication of liquid-infused surfaces using reactive polymer multilayers: principles for manipulating the behaviors and mobilities of aqueous fluids on slippery liquid interfaces.

    PubMed

    Manna, Uttam; Lynn, David M

    2015-05-20

    The design of slippery liquid-infused porous surfaces (SLIPS) using nanoporous and chemically reactive polymer multilayers is reported. This approach permits fabrication of slippery anti-fouling coatings on complex surfaces and provides new means to manipulate the mobilities of contacting aqueous fluids. The results expand the range of tools that can be used to manipulate the behaviors of SLIPS and open the door to new applications of this emerging class of soft materials.

  19. Fabrication of liquid-infused surfaces using reactive polymer multilayers: principles for manipulating the behaviors and mobilities of aqueous fluids on slippery liquid interfaces.

    PubMed

    Manna, Uttam; Lynn, David M

    2015-05-20

    The design of slippery liquid-infused porous surfaces (SLIPS) using nanoporous and chemically reactive polymer multilayers is reported. This approach permits fabrication of slippery anti-fouling coatings on complex surfaces and provides new means to manipulate the mobilities of contacting aqueous fluids. The results expand the range of tools that can be used to manipulate the behaviors of SLIPS and open the door to new applications of this emerging class of soft materials. PMID:25854608

  20. Dynamic behaviors of liquid droplets on a gas diffusion layer surface: Hybrid lattice Boltzmann investigation

    NASA Astrophysics Data System (ADS)

    Wu, Jie; Huang, Jun-Jie

    2015-07-01

    Water management is one of the key issues in proton exchange membrane fuel cells. Fundamentally, it is related to dynamic behaviors of droplets on a gas diffusion layer (GDL) surface, and consequently they are investigated in this work. A two-dimensional hybrid method is employed to implement numerical simulations, in which the flow field is solved by using the lattice Boltzmann method and the interface between droplet and gas is captured by solving the Cahn-Hilliard equation directly. One or two liquid droplets are initially placed on the GDL surface of a gas channel, which is driven by the fully developed Poiseuille flow. At a fixed channel size, the effects of viscosity ratio of droplet to gas ( μ ∗ ), Capillary number (Ca, ratio of gas viscosity to surface tension), and droplet interaction on the dynamic behaviors of droplets are systematically studied. By decreasing viscosity ratio or increasing Capillary number, the single droplet can detach from the GDL surface easily. On the other hand, when two identical droplets stay close to each other or a larger droplet is placed in front of a smaller droplet, the removal of two droplets is promoted.

  1. Using chemically patterns with different anchoring behavior to control the orientation of nematic liquid crystal

    NASA Astrophysics Data System (ADS)

    Li, Xiao; Armas Perez, Julio; Martinez-Gonzalez, Jose Adrian; Xie, Helou; de Pablo, Juan; Nealey, Paul

    2015-03-01

    We present experimental and theoretical study of nematic liquid crystal (5CB) confined to a thin cell between homeotropic anchoring top surface and chemically patterned planar/homeotropic anchoring bottom substrates. The chemically patterned substrate with different dimensions and ~ 4 nm depth topography induce the 5CB to align as the pattern direction as non-degenerate behavior, until the width of the straight line pattern is too wide to confine the 5CB to one direction and back to degenerate behavior. By changing the width of the straight line pattern, a brightness change of the intensity is shown by their corresponding crossed polarizer images. This change is mainly due to a discontinuity of the average angle between the molecules and the surface in function of line width, which is in excellent agreement with the Landan-de Gennes theory when the balance between the elastic deformation in the bulk and orientation of molecules close to the surface is simulated for different pattern dimensions. An elastic free energy transition is also observed from the numerical analysis when the strong planar anchoring for presented experiments is changed to weak. This 3D confinement by chemically patterns and small depth topography offers a new way to generate any geometry pattern controllable non-degenerate orientation, achieving switchable optical properties.

  2. Microgravity: Molecular Dynamics Simulations at the NCCS Probe the Behavior of Liquids in Low Gravity

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The life of the very small, whether in something as complicated as a human cell or as simple as a drop of water, is of fundamental scientific interest: By knowing how a tiny amount of material reacts to changes in its environment, scientists maybe able to answer questions about how a bulk of material would react to comparable changes. NASA is in the forefront of computational research into a broad range of basic scientific questions about fluid dynamics and the nature of liquid boundary instability. For example, one important issue for the space program is how drops of water and other materials will behave in the low-gravity environment of space and how the low gravity will affect the transport and containment of these materials. Accurate prediction of this behavior is among the aims of a set of molecular dynamics experiments carried out on the NCCSs Cray supercomputers. In conventional computational studies of materials, matter is treated as continuous - a macroscopic whole without regard to its molecular parts - and the behavior patterns of the matter in various physical environments are studied using well-established differential equations and mathematical parameters based on physical properties such as compressibility density, heat capacity, and vapor pressure of the bulk material.

  3. Reaction, Transport and Settling Behavior of Lead-Bismuth Eutectic in Flowing Liquid Sodium

    SciTech Connect

    Shinya Miyahara; Shuji Ohno; Nobuhiro Yamamoto; Junichi Saito; Masaru Hirabayashi

    2006-07-01

    The experimental study has been carried out to investigate reaction, transport and settling behavior of lead-bismuth eutectic (LBE) in flowing liquid sodium. In the test, 168 g of LBE were poured into flowing sodium from the top of a vertical-type sodium loop which contained 23.2 kg of sodium. The initial temperature of LBE and sodium was 673 K. The flow rate and the maximum velocity of sodium in the loop were controlled and measured at 20 dm{sup 3}/min and 1 m/sec, respectively, using an electro-magnetic pump and an electro-magnetic flow meter. The sodium loop has a settling chamber at the lower part to investigate the concentration decrease behavior of solid particle reaction products in the sodium due to the settling effect. The concentration was measured by sodium sampling from the 11 positions of the loop during the experiment and its post-test chemical analysis. The temperature changes at the various parts of the loop were also measured during the experiment by thermo-couples attached on the outer surface of the loop. Ultrasonic detectors were attached on the outer surface of the loop below the position of a LBE pour nozzle to demonstrate the utility as a leak detector. (authors)

  4. Hunger in red imported fire ants and their behavioral response to two liquid bait products.

    PubMed

    O'Brien, Kathryn S; Hooper-Bùi, Linda M

    2005-12-01

    To help manage red imported fire ant, Solenopsis invicta Buren, invasion, several types of pest management systems have been developed, including baits. To accurately test liquid bait effectiveness in the laboratory, we determined that starvation time of 96 h is required for laboratory fire ants to simulate foraging ants in the field. We measured density and viscosity of two commercial baits and 20% sugar water at 25 degrees C and then compared amount of material consumed per ant at these physical properties. Mean densities of 20% sugar water, Dr. Moss, and Terro were 1.051, 1.287, and 1.354 g/ml, respectively, and viscosity of each bait treatment varied in the same order but more drastically (1.7, 32, and 400 centipoises, respectively). Field and laboratory studies demonstrated that bait acceptability may be affected by toxicant and physical properties. Baits that are more dense have more mass per volume and may cause the ant to cease feeding with a lower crop load than when they feed on sugar water. Ants that feed on formulated baits exhibit feeding behaviors different from those that occur when feeding on sugar water. At first glance, one might conclude that the difference is because of the toxicant, but our findings suggest that physical properties of baits may be a factor in this change in feeding behavior.

  5. MASS-REMOVAL AND MASS-FLUX-REDUCTION BEHAVIOR FOR IDEALIZED SOURCE ZONES WITH HYDRAULICALLY POORLY-ACCESSIBLE IMMISCIBLE LIQUID

    SciTech Connect

    Brusseau, M. L.; Difilippo, Erica L.; marble, justin C.; Oostrom, Mart

    2008-04-01

    A series of flow-cell experiments was conducted to investigate aqueous dissolution and mass-removal behavior for systems wherein immiscible liquid was non-uniformly distributed in physically heterogeneous source zones. The study focused specifically on characterizing the relationship between mass flux reduction and mass removal for systems for which immiscible liquid is poorly accessible to flowing water. Two idealized scenarios were examined, one wherein immiscible liquid at residual saturation exists within a lower-permeability unit residing in a higher-permeability matrix, and one wherein immiscible liquid at higher saturation (a pool) exists within a higher-permeability unit adjacent to a lower-permeability unit. The results showed that significant reductions in mass flux occurred at relatively moderate mass-removal fractions for all systems. Conversely, minimalmass flux reduction occurred until a relatively large fraction of mass (>80%) was removed for the control experiment, which was designed to exhibit ideal mass removal. In general, mass flux reduction was observed to follow an approximately one-to-one relationship with mass removal. Two methods for estimating mass-flux-reduction/mass-removal behavior, one based on system-indicator parameters (ganglia-to-pool ratio) and the other a simple mass-removal function, were used to evaluate the measured data. The results of this study illustrate the impact of poorly accessible immiscible liquid on mass-removal and mass-flux processes, and the difficulties posed for estimating mass-flux-reduction/mass-removal behavior.

  6. Strongly correlated quantum spin liquid in herbertsmithite

    SciTech Connect

    Shaginyan, V. R.; Popov, K. G.; Khodel, V. A.

    2013-05-15

    Strongly correlated Fermi systems are among the most intriguing and fundamental systems in physics. We show that the herbertsmithite ZnCu{sub 3}(OH){sub 6}Cl{sub 2} can be regarded as a new type of strongly correlated electrical insulator that possesses properties of heavy-fermion metals with one exception: it resists the flow of electric charge. We demonstrate that herbertsmithite's low-temperature properties are defined by a strongly correlated quantum spin liquid made with hypothetic particles such as fermionic spinons that carry spin 1/2 and no charge. Our calculations of its thermodynamic and relaxation properties are in good agreement with recent experimental facts and allow us to reveal their scaling behavior, which strongly resembles that observed in heavy-fermion metals. Analysis of the dynamic magnetic susceptibility of strongly correlated Fermi systems suggests that there exist at least two types of its scaling.

  7. Carrier density independent scattering rate in SrTiO₃-based electron liquids

    DOE PAGES

    Mikheev, Evgeny; Raghavan, Santosh; Zhang, Jack Y.; Marshall, Patrick B.; Kajdos, Adam P.; Balents, Leon; Stemmer, Susanne

    2016-02-10

    We examine the carrier density dependence of the scattering rate in two- and three-dimensional electron liquids in SrTiO3 in the regime where it scales with Tn (T is the temperature and n ≤ 2) in the cases when it is varied by electrostatic control and chemical doping, respectively. It is shown that the scattering rate is independent of the carrier density. This is contrary to the expectations from Landau Fermi liquid theory, where the scattering rate scales inversely with the Fermi energy (EF). We discuss that the behavior is very similar to systems traditionally identified as non-Fermi liquids (n Fermi liquid theory should be questioned for a much broader range of correlated materials and point to the need for a unified theory.« less

  8. Correlation functions of one-dimensional Bose-Fermi mixtures

    SciTech Connect

    Frahm, Holger; Palacios, Guillaume

    2005-12-15

    We calculate the asymptotic behavior of correlators as a function of the microscopic parameters for an integrable Bose-Fermi mixture with repulsive interaction in one dimension. For two cases, namely polarized and unpolarized fermions the singularities of the momentum distribution functions are characterized as a function of the coupling constant and the relative density of bosons.

  9. Solitary waves in a nonintegrable Fermi-Pasta-Ulam chain

    NASA Astrophysics Data System (ADS)

    Truskinovsky, Lev; Vainchtein, Anna

    2014-10-01

    We present a family of exact solutions describing discrete solitary waves in a nonintegrable Fermi-Pasta-Ulam chain. The family is sufficiently rich to cover the whole spectrum of known behaviors from delocalized quasicontinuum waves moving with near-sonic velocities to highly localized anticontinuum excitations with only one particle moving at a time.

  10. Microencapsulation effects on the electro-optical behavior of polymer cholesteric liquid crystal flakes

    NASA Astrophysics Data System (ADS)

    Cox, Gerald Philip

    A modeling method is introduced for predicting the effect of microencapsulation on the electro-optical behavior of polymer cholesteric liquid crystal (PCLC) flakes suspended in a host fluid. The electric field acting on the flakes is significantly altered as various materials and boundary conditions are explored. The modeling predicts that test cells with multiple materials in the electric field path can have a wide range of electro-optic responses in AC electric fields. For DC drive conditions at high field strengths and test cell materials with low dielectric constants, electrophoretic behavior is observed for PCLC flakes. Prototype test cells for several encapsulation configurations are characterized for their resulting electro-optical behavior. The observed flake motions are in good agreement with the predicted results. This modeling method is shown to be a useful predictive tool for developing switchable particle devices utilizing microencapsulated dielectric particles in a host fluid medium. This work further builds on previous research on flake motion in a host fluid suspension, exploring flake doping effects, both internal and surface coated. Host fluids were also doped for increased conductivity and are explored for their effect on PCLC flake motion. A low dielectric property host fluid doped with an aqueous salt solution and a surfactant is found to enable Maxwell-Wagner reorientation in a DC electric field. In an AC electric field the doped host fluid is found to have dual-frequency response enabling a reverse drive for PCLC flakes. Below the turnover frequency, flakes align parallel to the electric field and above the turnover frequency the flakes align perpendicular.

  11. Hopping Conduction and Metallic behavior in 2D Silicon Surface States induced by an Ionic Liquid

    NASA Astrophysics Data System (ADS)

    Nelson, JJ

    Ionic liquids (ILs) are essentially molten salts with a melting point below room temperature. When used as the gate dielectric of a transistor, carrier densities on the order of 1015 cm-2 can be achieved. These record high carrier densities are significantly higher than the maximum carrier density achievable with oxide dielectrics. The physical mechanism for inducing carriers to such a high carrier density is not well understood. Some groups have reported that the induced carriers are a result of electrostatic and electrochemical processes. Other groups have suggested that carriers induced with an IL may be entirely due to electrochemical reactions. Here we report on IL gated Si at carrier densities from 1011 cm-2 to 1013 cm-2. The experiment was designed to preferentially induce electrostatic carriers over electrochemical reactions. At low carrier densities, sample surface conductivity follows nearest neighbor hopping conduction. This form of conduction has also been observed in experiments where surface conductivity was induced by implanting Na + near the oxide surface interface. A surprising result of this work was that in some samples a 2D metallic state could be created on the surface of Si. The transition to metallic behavior occurred just below 1013 cm-2. High quality Si transistors with oxide dielectric materials observe critical carrier densities around 1011 cm-2. The critical carrier density observed in IL gated Si is the highest density reported to date. At carrier densities higher than 1013 cm-2 it was observed that the sample conductivity decreased with increasing carrier density. The behavior was unexpected and not fully understood. Both metallic and non metallic samples show a similar reduction in conductivity that is not thought to be due to sample degradation by the IL. The reduction in the sample conductivity at high carrier densities is thought to be due to surface roughness scattering. Similar behavior has been observed in other IL gated

  12. [Dynamic behavior of aldicarb and its metabolites in cabbage by liquid chromatography-tandem mass spectrometry].

    PubMed

    Ding, Kuiying; Xu, Wenjuan; Li, Kai; Guo, Liqiang; Sun, Jun

    2016-02-01

    A liquid chromatography-tandem mass spectrometry ( LC-MS/MS ) method was developed for the study of dynamic behavior of aldicarb and its metabolite residues in cabbage. Aldicarb was applied onto cultivated cabbages. The pesticides concentrations were measured periodically (between application and harvest) , and modeled to illustrate the dynamic behavior. The results showed that the liner ranges of aldicarb and its metabolites were from 0. 005 to 0. 2 mg/L, and the recoveries ranged from 78. 9% to 108. 5% with the relative standard deviations of 2. 03%- 8. 91% (n = 8). The aldicarb in cabbage increased at first with the first-order kinetic equation model of c = 0. 020(0.136t) with the correlation coefficient (r2) of 0. 888, and then decreased with the equation of c = 0. 65e(-059t) with the r2 of 0. 979 and the half-life of 29. 1 d. The reducing processes of aldicarb-sulfone and aldicarb-sulfoxide both matched the first-order kinetic equations (c = 23. 4e(-0.044t) and c = 4. 54e(-0.027t) with r2 of 0. 916 and 0. 972 respectively. To meet the limitation requirement of 0. 01 mg/kg, 70. 7, 226. 6 and 176. 3 d were respectively necessary for aldicarb, aldicarb-sulfone and aldicarb-sulfoxide. Final residues of aldicarb-sulfone and aldicarb-sulfoxide were still more than the limitation requirements, indicating that aldicarb should not be used in vegetables of growth cycle shorter than 120 d. This study provided theoretical basis for dynamic behavior of aldicarb residue and its safe use in vegetables. PMID:27382721

  13. Structural behavior and interactions of dendrimer within lyotropic liquid crystals, monitored by EPR spectroscopy and rheology.

    PubMed

    Bitan-Cherbakovsky, Liron; Libster, Dima; Ottaviani, Maria Francesca; Aserin, Abraham; Garti, Nissim

    2012-03-01

    Micro- and macrostructural behaviors of three different lyotropic liquid crystals (LLCs) loaded with a dendrimer, namely second generation poly(propylene imine) (PPI-G2), were studied by means of rheology and electron paramagnetic resonance (EPR). The three mesophases were L(α), Q(224), and H(II) composed of glycerol monooleate (GMO) and water-PPI-G2 solution (and d-α-tocopherol (vitamin E) in the case of H(II)). We characterized the impact of PPI-G2 interactions with the components of the host mesophases on their structural characteristics on different length scales. The incorporation of PPI-G2 within the L(α) and H(II) systems induced the formation of more elastic hexagonal systems with a "solidlike" behavior, while in the Q(224) system a different trend with a "liquidlike" behavior was observed. As a result, the dendrimer induced a remarkable change in both the structural and viscoelastic properties of the systems. Hence, the microenvironment in the interface region within the systems was monitored by computer-aided EPR using 5-doxylstearic acid (5-DSA) as a pH-dependent probe. The microviscosity (τ) and order (S) of systems were found to be sensitive to the PPI-G2 presence: when PPI-G2 concentration increased, τ and S increased in both the L(α) and Q(224) systems. In the H(II) systems two trends were observed, reflecting a decrease in τ and S up to 10 wt % PPI-G2 and subsequently their increase at higher dendrimer concentrations. It was assessed that PPI-G2 interacted strongly with the GMO hydroxyl groups in the L(α) phase, with the water molecules in the Q(224) systems. In the H(II) mesophase strong interactions with both the water and GMO hydroxyl molecules were detected.

  14. A New Volume-Based Approach for Predicting Thermophysical Behavior of Ionic Liquids and Ionic Liquid Crystals.

    PubMed

    Nelyubina, Yulia V; Shaplov, Alexander S; Lozinskaya, Elena I; Buzin, Mikhail I; Vygodskii, Yakov S

    2016-08-17

    Volume-based prediction of melting points and other properties of ionic liquids (ILs) relies on empirical relations with volumes of ions in these low-melting organic salts. Here we report an accurate way to ionic volumes by Bader's partitioning of electron densities from X-ray diffraction obtained via a simple database approach. For a series of 1-tetradecyl-3-methylimidazolium salts, the volumes of different anions are found to correlate linearly with melting points; larger anions giving lower-melting ILs. The volume-based concept is transferred to ionic liquid crystals (ILs that adopt liquid crystalline mesophases, ILCs) for predicting the domain of their existence from the knowledge of their constituents. For 1-alkyl-3-methylimidazolium ILCs, linear correlations of ionic volumes with the occurrence of LC mesophase and its stability are revealed, thus paving the way to rational design of ILCs by combining suitably sized ions.

  15. A New Volume-Based Approach for Predicting Thermophysical Behavior of Ionic Liquids and Ionic Liquid Crystals.

    PubMed

    Nelyubina, Yulia V; Shaplov, Alexander S; Lozinskaya, Elena I; Buzin, Mikhail I; Vygodskii, Yakov S

    2016-08-17

    Volume-based prediction of melting points and other properties of ionic liquids (ILs) relies on empirical relations with volumes of ions in these low-melting organic salts. Here we report an accurate way to ionic volumes by Bader's partitioning of electron densities from X-ray diffraction obtained via a simple database approach. For a series of 1-tetradecyl-3-methylimidazolium salts, the volumes of different anions are found to correlate linearly with melting points; larger anions giving lower-melting ILs. The volume-based concept is transferred to ionic liquid crystals (ILs that adopt liquid crystalline mesophases, ILCs) for predicting the domain of their existence from the knowledge of their constituents. For 1-alkyl-3-methylimidazolium ILCs, linear correlations of ionic volumes with the occurrence of LC mesophase and its stability are revealed, thus paving the way to rational design of ILCs by combining suitably sized ions. PMID:27479022

  16. Three-phase liquid-liquid-vapor equilibria behavior of certain binary CO/sub 2/-n-paraffin systems

    SciTech Connect

    Hottovy, J.D.; Kohn, J.P.; Luks, K.D.

    1981-07-01

    The 3-phase liquid-liquid-vapor loci of 4 binary CO/sub 2/-n-paraffin systems (n-dodecane, n-tridecane, n-tetradecane, n-pentadecane) are studied, and temperature, pressure, and molar volumes and composition of both liquid phases are reported. It is within this group of n-paraffins that the nature of the upper critical end point for the CO/sub 2/-containing binary systems changes with increasing carbon number from an upper critical solution (temperature) point where L/sub 1/ and L/sub 2/ phases become critical in presence of vapor phase to a K point, where L/sub 2/ and vapor phases become critical in the presence of L/sub 1/ phase. These 4 loci are compared with earlier obtained loci on CO/sub 2/-n-decane and CO/sub 2/-n-elcosane.

  17. Lasing in Bose-Fermi mixtures

    PubMed Central

    Kochereshko, Vladimir P.; Durnev, Mikhail V.; Besombes, Lucien; Mariette, Henri; Sapega, Victor F.; Askitopoulos, Alexis; Savenko, Ivan G.; Liew, Timothy C. H.; Shelykh, Ivan A.; Platonov, Alexey V.; Tsintzos, Simeon I.; Hatzopoulos, Z.; Savvidis, Pavlos G.; Kalevich, Vladimir K.; Afanasiev, Mikhail M.; Lukoshkin, Vladimir A.; Schneider, Christian; Amthor, Matthias; Metzger, Christian; Kamp, Martin; Hoefling, Sven; Lagoudakis, Pavlos; Kavokin, Alexey

    2016-01-01

    Light amplification by stimulated emission of radiation, well-known for revolutionising photonic science, has been realised primarily in fermionic systems including widely applied diode lasers. The prerequisite for fermionic lasing is the inversion of electronic population, which governs the lasing threshold. More recently, bosonic lasers have also been developed based on Bose-Einstein condensates of exciton-polaritons in semiconductor microcavities. These electrically neutral bosons coexist with charged electrons and holes. In the presence of magnetic fields, the charged particles are bound to their cyclotron orbits, while the neutral exciton-polaritons move freely. We demonstrate how magnetic fields affect dramatically the phase diagram of mixed Bose-Fermi systems, switching between fermionic lasing, incoherent emission and bosonic lasing regimes in planar and pillar microcavities with optical and electrical pumping. We collected and analyzed the data taken on pillar and planar microcavity structures at continuous wave and pulsed optical excitation as well as injecting electrons and holes electronically. Our results evidence the transition from a Bose gas to a Fermi liquid mediated by magnetic fields and light-matter coupling. PMID:26822483

  18. Lasing in Bose-Fermi mixtures

    NASA Astrophysics Data System (ADS)

    Kochereshko, Vladimir P.; Durnev, Mikhail V.; Besombes, Lucien; Mariette, Henri; Sapega, Victor F.; Askitopoulos, Alexis; Savenko, Ivan G.; Liew, Timothy C. H.; Shelykh, Ivan A.; Platonov, Alexey V.; Tsintzos, Simeon I.; Hatzopoulos, Z.; Savvidis, Pavlos G.; Kalevich, Vladimir K.; Afanasiev, Mikhail M.; Lukoshkin, Vladimir A.; Schneider, Christian; Amthor, Matthias; Metzger, Christian; Kamp, Martin; Hoefling, Sven; Lagoudakis, Pavlos; Kavokin, Alexey

    2016-01-01

    Light amplification by stimulated emission of radiation, well-known for revolutionising photonic science, has been realised primarily in fermionic systems including widely applied diode lasers. The prerequisite for fermionic lasing is the inversion of electronic population, which governs the lasing threshold. More recently, bosonic lasers have also been developed based on Bose-Einstein condensates of exciton-polaritons in semiconductor microcavities. These electrically neutral bosons coexist with charged electrons and holes. In the presence of magnetic fields, the charged particles are bound to their cyclotron orbits, while the neutral exciton-polaritons move freely. We demonstrate how magnetic fields affect dramatically the phase diagram of mixed Bose-Fermi systems, switching between fermionic lasing, incoherent emission and bosonic lasing regimes in planar and pillar microcavities with optical and electrical pumping. We collected and analyzed the data taken on pillar and planar microcavity structures at continuous wave and pulsed optical excitation as well as injecting electrons and holes electronically. Our results evidence the transition from a Bose gas to a Fermi liquid mediated by magnetic fields and light-matter coupling.

  19. Compressible Strips, Chiral Luttinger Liquids, and All That Jazz

    NASA Astrophysics Data System (ADS)

    MacDonald, A. H.

    1996-03-01

    When the quantum Hall effect occurs in a two-dimensional electron gas, all low-energy elementary excitations are localized near the system edge. The edge acts in many ways like a one-dimensional ring of electrons, except that a finite current flows around the ring in equilibrium. This article is a brief and informal review of some of the physics of quantum Hall system edges. We discuss the implications of macroscopic {\\em compressible strip} models for microscopic {chiral Luttinger liquid} models and make an important distinction between the origin of non-Fermi-liquid behavior in fractional quantum Hall edges and in usual one-dimensional electron gas systems.

  20. Fermi surface, magnetic, and superconducting properties in actinide compounds

    NASA Astrophysics Data System (ADS)

    Ōnuki, Yoshichika; Settai, Rikio; Haga, Yoshinori; Machida, Yo; Izawa, Koichi; Honda, Fuminori; Aoki, Dai

    2014-08-01

    The de Haas-van Alphen effect, which is a powerful method to explore Fermi surface properties, has been observed in cerium, uranium, and nowadays even in neptunium and plutonium compounds. Here, we present the results of several studies concerning the Fermi surface properties of the heavy fermion superconductors UPt3 and NpPd5Al2, and of the ferromagnetic pressure-induced superconductor UGe2, together with those of some related compounds for which fascinating anisotropic superconductivity, magnetism, and heavy fermion behavior has been observed. xml:lang="fr"

  1. Hydrodynamics in a Degenerate, Strongly Attractive Fermi Gas

    NASA Technical Reports Server (NTRS)

    Thomas, John E.; Kinast, Joseph; Hemmer, Staci; Turlapov, Andrey; O'Hara, Ken; Gehm, Mike; Granade, Stephen

    2004-01-01

    In summary, we use all-optical methods with evaporative cooling near a Feshbach resonance to produce a strongly interacting degenerate Fermi gas. We observe hydrodynamic behavior in the expansion dynamics. At low temperatures, collisions may not explain the expansion dynamics. We observe hydrodynamics in the trapped gas. Our observations include collisionally-damped excitation spectra at high temperature which were not discussed above. In addition, we observe weakly damped breathing modes at low temperature. The observed temperature dependence of the damping time and hydrodynamic frequency are not consistent with collisional dynamics nor with collisionless mean field interactions. These observations constitute the first evidence for superfluid hydrodynamics in a Fermi gas.

  2. Chemistry in the Venus clouds: Sulfuric acid reactions and freezing behavior of aqueous liquid droplets

    NASA Astrophysics Data System (ADS)

    Delitsky, M. L.; Baines, K. H.

    2015-11-01

    Venus has a thick cloud deck at 40-70 km altitude consisting of liquid droplets and solid particles surrounded by atmospheric gases. The liquid droplets are highly concentrated aqueous solutions of sulfuric acid ranging in concentration from 70-99 wt%. Weight percent drops off with altitude (Imamura and Hashimoto 2001). There will be uptake of atmospheric gases into the droplet solutions and the ratios of gas-phase to liquid-phase species will depend on the Henry’s Law constant for those solutions. Reactions of sulfuric acid with these gases will form products with differing solubilities. For example, uptake of HCl by H2SO4/H2O droplets yields chlorosulfonic acid, ClSO3H (Robinson et al 1998) in solution. This may eventually decompose to thionyl- or sulfuryl chlorides, which have UV absorbances. HF will also uptake, creating fluorosulfonic acid, FSO3H, which has a greater solubility than the chloro- acid. As uptake continues, there will be many dissolved species in the cloudwaters. Baines and Delitsky (2013) showed that uptake will have a maximum at ~62 km and this is very close to the reported altitude for the mystery UV absorber in the Venus atmosphere. In addition, at very strong concentrations in lower altitude clouds, sulfuric acid will form hydrates such as H2SO4.H2O and H2SO4.4H2O which will have very different freezing behavior than sulfuric acid, with much higher freezing temperatures (Carslaw et al, 1997). Using temperature data from Venus Express from Tellmann et al (2009), and changes in H2SO4 concentrations as a function of altitude (James et al 1997), we calculate that freezing out of sulfuric acid hydrates can be significant down to as low as 56 km altitude. As a result, balloons, aircraft or other probes in the Venus atmosphere may be limited to flying below certain altitudes. Any craft flying at altitudes above ~55 km may suffer icing on the wings, propellers, balloons and instruments which could cause possible detrimental effects (thermal

  3. Ferromagnetism in a repulsive atomic Fermi gas with correlated disorder

    NASA Astrophysics Data System (ADS)

    Pilati, S.; Fratini, E.

    2016-05-01

    We investigate the zero-temperature ferromagnetic behavior of a two-component repulsive Fermi gas in the presence of a correlated random field that represents an optical speckle pattern. The density is tuned so that the (noninteracting) Fermi energy is close to the mobility edge of the Anderson localization transition. We employ quantum Monte Carlo simulations to determine various ground-state properties, including the equation of state, the magnetic susceptibility, and the energy of an impurity immersed in a polarized Fermi gas (repulsive polaron). In the weakly interacting limit, the magnetic susceptibility is found to be suppressed by disorder. However, it rapidly increases with the interaction strength, and it diverges at a much weaker interaction strength compared to the clean gas. Both the transition from the paramagnetic phase to the partially ferromagnetic phase, and the one from the partially to the fully ferromagnetic phase, are strongly favored by disorder, indicating a case of order induced by disorder.

  4. Radio-frequency spectroscopy of a strongly imbalanced Feshbach-resonant Fermi gas

    NASA Astrophysics Data System (ADS)

    Veillette, Martin; Moon, Eun Gook; Lamacraft, Austen; Radzihovsky, Leo; Sachdev, Subir; Sheehy, D. E.

    2008-09-01

    A sufficiently large species imbalance (polarization) in a two-component Feshbach resonant Fermi gas is known to drive the system into its normal state. We show that the resulting strongly interacting state is a conventional Fermi liquid, that is, however, strongly renormalized by pairing fluctuations. Using a controlled 1/N expansion, we calculate the properties of this state with a particular emphasis on the atomic spectral function, the momentum distribution functions displaying the Migdal discontinuity, and the radio frequency (rf) spectrum. We discuss the latter in the light of the recent experiments of [Schunck , Science 316, 867 (2007)] on such a resonant Fermi gas, and show that the observations are consistent with a conventional, but strongly renormalized Fermi-liquid picture.

  5. Mixtures of n-octyl-beta-D-glucoside and triethylene glycol mono-n-octyl ether: phase behavior and micellar structure near the liquid-liquid phase boundary.

    PubMed

    Santonicola, Gabriella M; Kaler, Eric W

    2005-10-25

    The phase behavior and microstructure of aqueous mixtures of n-octyl-beta-D-glucoside (C8betaG1) and triethylene glycol mono-n-octyl ether (C8E3) is presented. C8betaG1 forms a one-phase micellar solution in water at surfactant concentrations up to 60 wt %, whereas mixtures with C8E3 show a liquid-liquid phase transition at low surfactant concentration. The position of this phase boundary for mixtures can be rationally shifted in the temperature-composition window by altering the ratio of the two surfactants. Small-angle neutron scattering is used to determine the size and shape of the mixed micelles and to characterize the nature of the fluctuations near the cloud point of the micellar solutions. The C8betaG1/C8E3 solutions are characterized by concentration fluctuations that become progressively stronger upon approach to the liquid-liquid phase boundary, whereas micellar growth is negligible. Such observations confirm previous views of the role of the surfactant phase boundary in tuning attractive micellar interactions, which can be used effectively to change the nature and strength of interparticle interactions in colloidal dispersions. Colloidal silica particles were then added to these surfactant mixtures and were found to aggregate at conditions near the cloud point. This finding is relevant to current strategies for protein crystallization.

  6. Vapor-liquid phase behavior of the iodine-sulfur water-splitting process : LDRD final report for FY03.

    SciTech Connect

    Bradshaw, Robert W.; Larson, Richard S.; Lutz, Andrew E.

    2004-01-01

    This report summarizes the results of a one-year LDRD project that was undertaken to better understand the equilibrium behavior of the iodine-water-hydriodic acid system at elevated temperature and pressure. We attempted to extend the phase equilibrium database for this system in order to facilitate development of the iodine-sulfur water-splitting process to produce hydrogen to a commercial scale. The iodine-sulfur cycle for thermochemical splitting of water is recognized as the most efficient such process and is particularly well suited to coupling to a high-temperature source of process heat. This study intended to combine experimental measurements of vapor-liquid-liquid equilibrium and equation-of-state modeling of equilibrium solutions using Sandia's Chernkin software. Vapor-liquid equilibrium experiments were conducted to a limited extent. The Liquid Chernkin software that was developed as part of an earlier LDRD project was enhanced and applied to model the non-ideal behavior of the liquid phases.

  7. X-ray imaging for studying behavior of liquids at high pressures and high temperatures using Paris-Edinburgh press

    SciTech Connect

    Kono, Yoshio; Kenney-Benson, Curtis; Park, Changyong; Shen, Guoyin; Shibazaki, Yuki; Wang, Yanbin

    2015-07-15

    Several X-ray techniques for studying structure, elastic properties, viscosity, and immiscibility of liquids at high pressures have been integrated using a Paris-Edinburgh press at the 16-BM-B beamline of the Advanced Photon Source. Here, we report the development of X-ray imaging techniques suitable for studying behavior of liquids at high pressures and high temperatures. White X-ray radiography allows for imaging phase separation and immiscibility of melts at high pressures, identified not only by density contrast but also by phase contrast imaging in particular for low density contrast liquids such as silicate and carbonate melts. In addition, ultrafast X-ray imaging, at frame rates up to ∼10{sup 5} frames/second (fps) in air and up to ∼10{sup 4} fps in Paris-Edinburgh press, enables us to investigate dynamics of liquids at high pressures. Very low viscosities of melts similar to that of water can be reliably measured. These high-pressure X-ray imaging techniques provide useful tools for understanding behavior of liquids or melts at high pressures and high temperatures.

  8. The thermodynamical response functions and the origin of the anomalous behavior of liquid water.

    PubMed

    Mallamace, Francesco; Corsaro, Carmelo; Mallamace, Domenico; Vasic, Cirino; Stanley, H Eugene

    2013-01-01

    The density maximum of water dominates the thermodynamics of the system under ambient conditions, is strongly P-dependent, and disappears at a crossover pressure P(cross) approximately 1.8 kbar. We study this variable across a wide area of the T-P phase diagram. We consider old and new data of both the isothermal compressibility K(T)(T, P), the pressure constant specific heat C(P)(T) and the coefficient of thermal expansion alpha(P) (T, P). We observe that K(T)(T) shows a minimum at T* approximately 315 +/- 5 K for all of the studied pressures, whereas, at the same temperature, C(P)(T) has the minimal variation as a function of P in the interval 1 bar-4 kbar. We find the behavior of alpha(P) also to be surprising: all the alpha(P)(T) curves measured at different P cross at T*. The experimental data show a "singular and universal expansivity point" at T* approximately 315 K and alpha(P)(T*) = 0.44 10(-3) K(-1). Unlike other water singularities, we find this temperature to be thermodynamically consistent in the relationship connecting the three response functions. By considering also the P-T behavior of the self-diffusion coefficient D(S) and of the NMR proton chemical shift delta we have the information that at T* the water local order points out, with decreasing T, the crossover from a normal fluid to the anomalous and complex liquid characterized by the many anomalies.

  9. Liquid Metal Pool Behavior during the Vacuum Arc Remelting of INCONEL 718

    NASA Astrophysics Data System (ADS)

    Shevchenko, D. M.; Ward, R. M.

    2009-06-01

    Non-steady-state ensemble arc behavior has been observed during the Vacuum Arc Remelting (VAR) of 508-mm-diameter ingots of INCONEL 718. The liquid metal flow in the melt pool of a 508-mm ingot during VAR has been simulated under two alternative sets of conditions: (1) a steady-state axisymmetrical arc distribution, as has been typically used in modeling work previously; and (b) a transient asymmetrical arc distribution. Due to the computational requirements, neither mass flux nor solidification were modeled; instead, the pool shape was fixed from measurements from a 508-mm-diameter ingot, and a constant pool wall temperature of 1609 K was used. The transient simulation assumed a localized Gaussian arc whose effective center was located at a distance of 0.1 m from the ingot centerline; this simulation rotated clockwise around the centerline with a period of 36 seconds. The steady-state model was simulated with axisymmetrical distributions of current and power input to the pool top surface calculated by time averaging the transient current and power inputs. The standard k- ɛ solver of ANSYS CFX 5.6 software was used for both simulations. The transient model results suggest that 5 seconds of asymmetrical arc behavior is enough to change the pool from steady state to transient and that, after 30 seconds, the flow is almost fully developed (at least to the accuracy of the model) and dominated by the Lorentz force. Aspects of the model results agree with key features of the melt pool observed during VAR.

  10. Thermodynamics of Thomas-Fermi screened Coulomb systems

    NASA Technical Reports Server (NTRS)

    Firey, B.; Ashcroft, N. W.

    1977-01-01

    We obtain in closed analytic form, estimates for the thermodynamic properties of classical fluids with pair potentials of Yukawa type, with special reference to dense fully ionized plasmas with Thomas-Fermi or Debye-Hueckel screening. We further generalize the hard-sphere perturbative approach used for similarly screened two-component mixtures, and demonstrate phase separation in this simple model of a liquid mixture of metallic helium and hydrogen.

  11. Thomas-Fermi molecular dynamics

    SciTech Connect

    Clerouin, J.; Pollock, E.L. ); Zerah, G. )

    1992-10-15

    A three-dimensional density-functional molecular-dynamics code is developed for the Thomas-Fermi density functional as a prototype for density functionals using only the density. Following Car and Parrinello (Phys. Rev. Lett. 55, 2471 (1985)), the electronic density is treated as a dynamical variable. The electronic densities are verified against a multi-ion Thomas-Fermi algorithm due to Parker (Phys. Rev. A 38, 2205 (1988)). As an initial application, the effect of electronic polarization in enhancing ionic diffusion in strongly coupled plasmas is demonstrated.

  12. Modified spin-wave theory and spin-liquid behavior of cold bosons on an inhomogeneous triangular lattice

    NASA Astrophysics Data System (ADS)

    Celi, Alessio; Grass, Tobias; Ferris, Andrew J.; Padhi, Bikash; Raventós, David; Simonet, Juliette; Sengstock, Klaus; Lewenstein, Maciej

    2016-08-01

    Ultracold bosons in a triangular lattice are a promising candidate for observing quantum spin liquid behavior. Here we investigate, for such system, the role of a harmonic trap giving rise to an inhomogeneous density. We construct a modified spin-wave theory for arbitrary filling and predict the breakdown of order for certain values of the lattice anisotropy. These regimes, identified with the spin liquid phases, are found to be quite robust upon changes in the filling factor. This result is backed by an exact diagonalization study on a small lattice.

  13. Corrosion sensitization behavior and mechanical properties of liquid-nitrogen-deformed austenitic 304 stainless steel

    NASA Astrophysics Data System (ADS)

    Maldonado, Julio Gerardo

    Plastic deformation of 304 stainless steel at liquid nitrogen temperature ({-}196sp°C) produces an almost complete transformation to strain-induced alphasp'/-martensite which provides the necessary conditions for a pseudo-recrystallization of the microstructure. This "so-called" pseudo-recrystallization results directly from the martensitic reversion (i.e. martensite to austenite reverse transformation) upon the application of heat treatment within the sensitization temperature range. The very fine duplex (alpha/gamma) microstructure which results (after heat treatment-0.1h-670sp°C) is also accompanied by a very extensive and homogeneous precipitation of chromium-rich carbides. The concomitant pseudo-recrystallization and precipitation processes not only have a profound positive effect on the sensitization behavior, but also affect the mechanical properties of the material. This suggests that 304 stainless steel could be thermo-mechanically treated, to in essence, heal itself and simultaneously produce an extremely fine (≈0.1mum) duplex grain structure with intermixed carbides to form a very high strength product. This might have important practical implications since 304 stainless steel is the material of choice in many engineering applications. Electrochemical testing, transmission electron microscopy, scanning electron microscopy, optical microscopy, neutron diffraction, X-ray diffraction, and mechanical testing were some of the techniques employed in this work.

  14. Charge Density Wave Behavior of Ionic Liquid Gated Strontium Titanate Nanowires

    NASA Astrophysics Data System (ADS)

    Bretz-Sullivan, Terence; Goldman, Allen

    2015-03-01

    Measurements of the current-voltage characteristics of ionic liquid gated nanometer scale channels of strontium titanate have been carried out. These characteristics exhibit a large voltage threshold for conduction and a nonlinear power law behavior at all temperatures measured. The source-drain current of these nanowires scales as a power law of the difference between the source-drain voltage and the threshold voltage. The temperature dependence of the threshold voltage appears to be related to the inverse of the temperature dependent dielectric constant of strontium titanate in qualitative agreement with a simple model of charge density wave depinning. These observations, when taken together, are evidence that a gate induced charge density wave has been induced, and is depinned by strong electric fields. This work was supported by DOE Basic Energy Sciences Grant DE-FG02-02ER46004. Samples were fabricated at the Minnesota Nanofabrication Center. Parts of this work were carried out in the University of Minnesota Characterization Facility, a member of the Materials Research Facilities Network (www.mrfn.org) funded via the NSF MRSEC program.

  15. Salt effects on the phase behavior, structure, and rheology of chromonic liquid crystals.

    PubMed

    Kostko, Andrei F; Cipriano, Bani H; Pinchuk, Olga A; Ziserman, Lior; Anisimov, Mikhail A; Danino, Dganit; Raghavan, Srinivasa R

    2005-10-20

    Chromonic liquid crystals are formed by the addition of aromatic molecules such as disodium chromoglycate (cromolyn) to water. In this study, we investigate the addition of salts to the lyotropic nematic phase of cromolyn aqueous solutions. The addition of sodium and potassium salts shifts the isotropic-nematic phase boundary upward by more than 10 degrees C, so that samples that were isotropic at room temperature are transformed into nematic phases. Salt effects are predominantly dictated by the cation, not the anion, and appear to differ based on cation size. In contrast to small, hydrated cations like sodium, large, weakly hydrated cations such as tetraethylammonium and tetrabutylammonium shift the phase boundary downward, thus stabilizing the isotropic phase at the expense of the nematic one. The phase behavior results are highly correlated with viscosity measurements, with an upward shift in the phase boundary correlating with an increase in solution viscosity and vice versa. We also probe the microstructure in cromolyn-salt solutions, both indirectly by small-angle neutron scattering (SANS) and directly by cryo-transmission electron microscopy (cryo-TEM). The cryo-TEM images show the presence of rodlike aggregates that possibly undergo a higher order aggregation into bundles in the presence of salt.

  16. Adsorption Behavior of Low-Concentration Imidazolium-Based Ionic Liquid Surfactant on Silica Nanoparticles.

    PubMed

    Liu, Yan; Qiao, Longjiao; Xiang, Yinping; Guo, Rong

    2016-03-22

    The adsorption behavior of imidazolium-based ionic liquid surfactant ([C12mim]Br) on silica nanoparticles (NPs) has been studied with turbidity, isothermal titration microcalorimetry, fluorescence spectroscopy, and dynamic light scattering (DLS) measurements. Both the electrostatic attraction and the hydrogen bonding interaction between silica NP and [C12mim]Br play crucial roles during [C12mim]Br monomers binding to silica NPs at low surfactant concentration, and the hydrophobic effect leads to formation of micelle-like aggregates on silica NP surfaces with the further increase of surfactant concentration. Furthermore, it is found that sodium halide salts favor the adsorption of [C12mim]Br on silica NP surfaces by decreasing the electrostatic repulsions. Anions with more hydrophobicity and the ability to form hydrogen bonding have more pronounced effect. Compared with DTAB, [C12mim]Br has much stronger binding ability with silica NPs at pH 7.0. More interestingly, [C12mim]Br can still form micelle-like aggregates on silica NP surfaces, but DTAB cannot at pH 2.0. The hydrogen bonding between the imidazolium ring and silica NPs is the principal contributor to these observations. Our results will contribute to the elucidation of silica NP/cationic surfactant interaction from molecular scale and the widely applications of silica NP/surfactant systems in practice.

  17. Phase Behavior of Blends of Polymers and Smectic-A Liquid Crystals.

    PubMed

    Benmouna; Coqueret; Maschke; Benmouna

    1998-07-28

    The phase behavior of blends of polymers and smectic-A liquid crystals (LCs) is investigated using Flory-Huggins and Maier-Saupe-McMillan theories. Various examples are considered to depict the effects of the architecture and the size of the polymer together with the nature of anisotropic ordering forces on the phase diagram. The strength of these forces is characterized by a parameter alpha which is directly related to the temperature of the smectic-nematic transition. Three cases are considered depending on the value of alpha, and the corresponding phase diagrams are constructed. Substantial differences are observed in these diagrams, and the reasons for these differences are discussed. A comparative study is performed between mixtures of polymers and LCs, where the polymer is made of linear and crosslinked chains. The LC consists either of molecules with nematic ordering only or of molecules presenting both nematic and smectic-A ordering. Blends where polymer matrices are cross-linked networks are also examined. Remarkable properties are found in the nature of the phase diagrams for such mixtures. In general, it is observed that the ordering forces favor unmixing with a stronger effect for the higher smectic-A ordering. Spinodal curves are also reported for these mixtures. The effects of fluctuations near the transition temperatures are briefly discussed.

  18. Behavior of a heavy cylinder in a horizontal cylindrical liquid-filled cavity at modulated rotation

    NASA Astrophysics Data System (ADS)

    Kozlov, Nikolai V.; Vlasova, Olga A.

    2016-10-01

    The behavior of a heavy cylindrical solid in a horizontal cylindrical cavity is experimentally investigated. The cavity is filled with a viscous liquid and rotates. Two rotation regimes are considered. The first one is steady rotation. A number of body motion regimes are found depending on the cavity rotation speed. The second regime is a modulated rotation, in which the rotation speed is varying periodically. It can be presented as a sum of steady rotation and librations. On the whole, three different cases of the body repulsion from the cavity wall are observed. In the first case, the repulsion occurs when the body slides over a rotating cavity wall. In the second case, the body being in the centrifuged state—when it rotates with the fluid—detaches from the cavity wall under the action of gravity. In the third case, at librations, the wall performs oscillations and the body is repulsed from the wall due to the nonlinear viscous interaction with the fluid.

  19. Density-functional theory and Monte Carlo simulations of the phase behavior of a simple model liquid crystal.

    PubMed

    Giura, Stefano; Schoen, Martin

    2014-08-01

    We consider the phase behavior of a simple model of a liquid crystal by means of modified mean-field density-functional theory (MMF DFT) and Monte Carlo simulations in the grand canonical ensemble (GCEMC). The pairwise additive interactions between liquid-crystal molecules are modeled via a Lennard-Jones potential in which the attractive contribution depends on the orientation of the molecules. We derive the form of this orientation dependence through an expansion in terms of rotational invariants. Our MMF DFT predicts two topologically different phase diagrams. At weak to intermediate coupling of the orientation dependent attraction, there is a discontinuous isotropic-nematic liquid-liquid phase transition in addition to the gas-isotropic liquid one. In the limit of strong coupling, the gas-isotropic liquid critical point is suppressed in favor of a fluid- (gas- or isotropic-) nematic phase transition which is always discontinuous. By considering three representative isotherms in parallel GCEMC simulations, we confirm the general topology of the phase diagram predicted by MMF DFT at intermediate coupling strength. From the combined MMF DFT-GCEMC approach, we conclude that the isotropic-nematic phase transition is very weakly first order, thus confirming earlier computer simulation results for the same model [see M. Greschek and M. Schoen, Phys. Rev. E 83, 011704 (2011)].

  20. Fermi Finds Youthful Pulsar Among Ancient Stars

    NASA Video Gallery

    In three years, NASA's Fermi has detected more than 100 gamma-ray pulsars, but something new has appeared. Among a type of pulsar with ages typically numbering a billion years or more, Fermi has fo...

  1. ABJM theory as a Fermi gas

    NASA Astrophysics Data System (ADS)

    Mariño, Marcos; Putrov, Pavel

    2012-03-01

    The partition function on the 3-sphere of many supersymmetric Chern-Simons-matter theories reduces, by localization, to a matrix model. We develop a new method to study these models in the M-theory limit, but at all orders in the 1/N expansion. The method is based on reformulating the matrix model as the partition function of an ideal Fermi gas with a non-trivial, one-particle quantum Hamiltonian. This new approach leads to a completely elementary derivation of the N3/2 behavior for ABJM theory and {N}=3 quiver Chern-Simons-matter theories. In addition, the full series of 1/N corrections to the original matrix integral can be simply determined by a next-to-leading calculation in the WKB or semiclassical expansion of the quantum gas, and we show that, for several quiver Chern-Simons-matter theories, it is given by an Airy function. This generalizes a recent result of Fuji, Hirano and Moriyama for ABJM theory. It turns out that the semiclassical expansion of the Fermi gas corresponds to a strong coupling expansion in type IIA theory, and it is dual to the genus expansion. This allows us to calculate explicitly non-perturbative effects due to D0- and D2-brane instantons in the AdS background.

  2. Fermi's Large Area Telescope (LAT)

    NASA Video Gallery

    Fermi’s Large Area Telescope (LAT) is the spacecraft’s main scientificinstrument. This animation shows a gamma ray (purple) entering the LAT,where it is converted into an electron (red) and a...

  3. CCC and the Fermi paradox

    NASA Astrophysics Data System (ADS)

    Gurzadyan, V. G.; Penrose, R.

    2016-01-01

    Within the scheme of conformal cyclic cosmology (CCC), information can be transmitted from aeon to aeon. Accordingly, the "Fermi paradox" and the SETI programme --of communication by remote civilizations-- may be examined from a novel perspective: such information could, in principle, be encoded in the cosmic microwave background. The current empirical status of CCC is also discussed.

  4. Fermi, Enrico (1901-54)

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    Italian physicist, created the first controlled chain reaction, founded Argonne National Laboratory. His work on the properties of electrons (spin-half particles like electrons are called fermions after him, and the study of their properties is called Fermi-Dirac statistics) enabled the pressure source in white dwarf stars to be identified, and white dwarf star properties to be calculated by CHAN...

  5. Fermi's β-DECAY Theory

    NASA Astrophysics Data System (ADS)

    Yang, Chen Ning

    2013-05-01

    Throughout his lifetime Enrico Fermi (1901-1954) had considered his 1934 β-decay theory as his most important contribution to theoretical physics. E. Segrè (1905-1989) had vividly written about an episode at the inception of that paper:1...

  6. Photonic crystal fiber with a dual-frequency addressable liquid crystal: behavior in the visible wavelength range.

    PubMed

    Lorenz, A; Kitzerow, H-S; Schwuchow, A; Kobelke, J; Bartelt, H

    2008-11-10

    Wave-guiding in the visible spectral range is investigated for a micro-structured crystal fiber filled with a dual-frequency addressable nematic liquid crystal mixture. The fiber exhibits a solid core surrounded by just 4 rings of cylindrical holes. Control of the liquid crystal alignment by anchoring agents permits relatively low attenuation. Samples with different anchoring conditions at the interface of the silica glass and the liquid crystal show different transmission properties and switching behavior. Polarization dependent and independent fiber optic switching is observed. Due to a dualfrequency addressing scheme, active switching to both states with enhanced and reduced transmission becomes possible for planar anchoring. Even a non-perfect fiber shows reasonable transmission and a variety of interesting effects.

  7. Photonic crystal fiber with a dual-frequency addressable liquid crystal: behavior in the visible wavelength range.

    PubMed

    Lorenz, A; Kitzerow, H-S; Schwuchow, A; Kobelke, J; Bartelt, H

    2008-11-10

    Wave-guiding in the visible spectral range is investigated for a micro-structured crystal fiber filled with a dual-frequency addressable nematic liquid crystal mixture. The fiber exhibits a solid core surrounded by just 4 rings of cylindrical holes. Control of the liquid crystal alignment by anchoring agents permits relatively low attenuation. Samples with different anchoring conditions at the interface of the silica glass and the liquid crystal show different transmission properties and switching behavior. Polarization dependent and independent fiber optic switching is observed. Due to a dualfrequency addressing scheme, active switching to both states with enhanced and reduced transmission becomes possible for planar anchoring. Even a non-perfect fiber shows reasonable transmission and a variety of interesting effects. PMID:19582031

  8. Pressure profiles of nonuniform two-dimensional atomic Fermi gases

    NASA Astrophysics Data System (ADS)

    Martiyanov, Kirill; Barmashova, Tatiana; Makhalov, Vasiliy; Turlapov, Andrey

    2016-06-01

    Spatial profiles of the pressure have been measured in atomic Fermi gases with primarily two-dimensional (2D) kinematics. The in-plane motion of the particles is confined by a Gaussian-shape potential. The two-component deeply degenerate Fermi gases are prepared at different values of the s -wave attraction. The pressure profile is found using the force-balance equation, from the measured density profile and the trapping potential. The pressure is compared to zero-temperature models within the local density approximation. In the weakly interacting regime, the pressure lies above a Landau Fermi-liquid theory and below the ideal-Fermi-gas model, whose prediction coincides with that of the Cooper-pair mean-field theory. The values closest to the data are provided by the approach where the mean field of Cooper pairs is supplemented with fluctuations. In the regime of strong interactions, in response to the increasing attraction, the pressure shifts below this model reaching lower values calculated within Monte Carlo methods. Comparison to models shows that interaction-induced departure from 2D kinematics is either small or absent. In particular, comparison with a lattice Monte Carlo suggests that kinematics is two dimensional in the strongly interacting regime.

  9. Cholesteric and nematic liquid crystalline phase behavior of double-stranded DNA stabilized single-walled carbon nanotube dispersions.

    PubMed

    Ao, Geyou; Nepal, Dhriti; Aono, Michelle; Davis, Virginia A

    2011-02-22

    The first lyotropic cholesteric single-walled carbon nanotube (SWNT) liquid crystal phase was obtained by dispersing SWNTs in an aqueous solution of double-stranded DNA (dsDNA). Depending on the dispersion methodology, the polydomain nematic phase previously reported for other lyotropic carbon nanotube dispersions could also be obtained. The phase behavior and dispersion microstructure were affected by the relative concentrations of dsDNA and SWNT and whether small bundles were removed prior to concentrating the dispersions. This readily controlled phase behavior opens new routes for producing SWNT films with controlled morphology.

  10. Study of the corrosion behaviors of 304 austenite stainless steel specimens exposed to static liquid lithium at 600 K

    NASA Astrophysics Data System (ADS)

    Meng, Xiancai; Zuo, Guizhong; Ren, Jun; Xu, Wei; Sun, Zhen; Huang, Ming; Hu, Wangyu; Hu, Jiansheng; Deng, Huiqiu

    2016-11-01

    Investigation of corrosion behavior of stainless steel served as one kind of structure materials exposed to liquid lithium (Li) is one of the keys to apply liquid Li as potential plasma facing materials (PFM) or blanket coolant in the fusion device. Corrosion experiments of 304 austenite stainless steel (304 SS) were carried out in static liquid Li at 600 K and up to1584 h at high vacuum with pressure less than 4 × 10-4 Pa. After exposure to liquid Li, it was found that the weight of 304 SS slightly decreased with weight loss rate of 5.7 × 10-4 g/m2/h and surface hardness increased by about 50 HV. Lots of spinel-like grains and holes were observed on the surface of specimens measured by SEM. By further EDS, XRD and metallographic analyzing, it was confirmed that the main compositions of spinel-like grains were M23C6 carbides, and 304 SS produced a non-uniform corrosion behavior by preferential grain boundary attack, possibly due to the easy formation of M23C6 carbides and/or formation of Li compound at grain boundaries.

  11. Oxidation behavior of ferritic/martensitic steels in stagnant liquid LBE saturated by oxygen at 600 °C

    NASA Astrophysics Data System (ADS)

    Shi, Quanqiang; Liu, Jian; Luan, He; Yang, Zhenguo; Wang, Wei; Yan, Wei; Shan, Yiyin; Yang, Ke

    2015-02-01

    Ferritic/martensitic (F/M) steels are primary candidates for application as cladding and structural materials in the Generation IV Nuclear Reactor, especially accelerator driven sub-critical system (ADS). The compatibility of F/M steels with liquid lead-bismuth eutectic (LBE) is a critical issue for development of ADS using liquid LBE as the coolant. In this work, the corrosion tests of two F/M steels, including a novel 9-12 Cr modified F/M steel named SIMP steel and a commercial T91 steel, were conducted in the static oxygen-saturated liquid LBE at 600 °C up to 1000 h, the microstructure of the oxide scale formed on these two steels was analyzed, the relationship between the microstructure and the oxidation behavior was studied, and the reason why the SIMP steel showed better oxidation resistance compared to T91 steel was analyzed. The results of this study confirmed that the oxidation behavior of the F/M steels in liquid metals is influenced by their alloying elements and microstructures.

  12. Buoyant thermocapillary flow with nonuniform supra-heating. I - Liquid-phase behavior. II - Two-phase behavior

    NASA Technical Reports Server (NTRS)

    Schiller, David N.; Sirignano, William A.

    1992-01-01

    The present computational study of transient heat transfer and fluid flow in a circular pool of n-decane which is undergoing central radiative heating from above gives attention to the volumetric absorption of the radiation incident on the pool surface. The first part of this study notes that buoyancy influences the number and recirculation rates of the subsurface vortices by stabilizing hot subsurface fluid above the colder core fluid; this affects the liquid surface temperature profile and in turn governs the velocity profile that is due to thermocapillarity. In the second part, the effects of gas-liquid phase coupling, variable density and thermophysical properties, and vaporization are considered.

  13. Factors affecting order, photopolymerization behavior, and nanostructure development of reactive lyotropic liquid crystals

    NASA Astrophysics Data System (ADS)

    Sievens Figueroa, Lucas

    2009-10-01

    Polymerization of reactive lyotropic liquid crystals (LLC) provides a facile means for the synthesis of nanostructured organic materials. In this work the photopolymerization kinetics and polymer structure evolution have been investigated. By studying the polymerization behavior and the order retention after polymerization, the contribution of the type of reactive surfactant, cross-linking, pH, and ionic strength on the LLC order preservation has been determined. Polymerization rates are higher in more highly ordered LLC phases compared to isotropic phases. In turn, reactive LLC phases that exhibit higher reaction rates also preserve the order to a greater extent during polymerization. Reactive surfactants with longer aliphatic tails exhibit lower order and lower reaction rates. The polymerization kinetics are highly driven by segregation of the reactive groups. Lower polymerization rates are observed in isotropic discontinuous phases for the surfactant monomer bearing the reactive group near the polar head while the opposite behavior is observed for surfactant monomer bearing the reactive group in the aliphatic tail. The effect of polymerization kinetics on the resulting polymer order has also been determined using small angle X-ray scattering (SAXS). By using high light intensity and a more efficient initiator, the LLC order is more likely to be retained after polymerization. LLC phases that exhibit higher degrees of order are formed at low ionic strength and low pH. Higher polymerization rates are observed as the ionic strength increases due to an increase in the propagation rate. Higher polymerization rates are also observed as the pH increases due to an increase in the propagation rates and decrease in termination rates. The addition of a crosslinker enables the retention of LLC phases after polymerization. Competing effects between crosslinking and order are observed in the polymerization kinetics as a decrease in polymerization rate is observed at high

  14. Possible spin liquid behavior in Sc2Ga2CuO7

    NASA Astrophysics Data System (ADS)

    Mahajan, A. V.; Kumar, R.; Khuntia, P.; Sheptyakov, D.; Freeman, P. G.; Ronnow, H. M.; Koteswararao, B.; Baenitz, M.; Furukawa, Y.; Jeong, M.

    The title compound crystallizes in a hexagonal structure (space group P63/mmc) containing edge-shared triangular planes as also triangular bi-planes. Our work establishes that the single triangular layers mainly have S = 0 Ga3+(85% Ga, 15% Cu), while the bi-layers contain 43% Cu2+ and 57% Ga3+, as far as the cations are concerned. Our χ (T) data shows no spin-freezing or magnetic long-range order (LRO) down to 1.8 K. We infer an effective moment of 1.79 μB and a θCW of about -50 K, suggesting AF interactions. In our specific heat data, no anomalies were found down to 0.35 K, in the field range 0-140 kOe. The magnetic specific heat has a nearly T2 power-law behavior at low- T (for H > 90 kOe). The 71Ga nuclear magnetic resonance (NMR) shift K (T) displays a broad maximum at T ~ 50 K. The 71Ga spin lattice relaxation rate 1/T1 displays a T 3 . 2 power-law increase from 0.1 K to 2 K, then remains nearly unchanged up to 10 K, and increases thereafter. Once again, down to 100 mK there is no indication of LRO which is usually manifested as an anomaly in the T-dependence of K and 1/T1. Our data suggest the formation of a quantum spin liquid in the S = 1 / 2 system Sc2Ga2CuO7.

  15. The Gamma-ray Sky with Fermi

    NASA Technical Reports Server (NTRS)

    Thompson, David

    2012-01-01

    Gamma rays reveal extreme, nonthermal conditions in the Universe. The Fermi Gamma-ray Space Telescope has been exploring the gamma-ray sky for more than four years, enabling a search for powerful transients like gamma-ray bursts, novae, solar flares, and flaring active galactic nuclei, as well as long-term studies including pulsars, binary systems, supernova remnants, and searches for predicted sources of gamma rays such as dark matter annihilation. Some results include a stringent limit on Lorentz invariance derived from a gamma-ray burst, unexpected gamma-ray variability from the Crab Nebula, a huge gamma-ray structure associated with the center of our galaxy, surprising behavior from some gamma-ray binary systems, and a possible constraint on some WIMP models for dark matter.

  16. The Gamma-ray Universe through Fermi

    NASA Technical Reports Server (NTRS)

    Thompson, David J.

    2012-01-01

    Gamma rays, the most powerful form of light, reveal extreme conditions in the Universe. The Fermi Gamma-ray Space Telescope and its smaller cousin AGILE have been exploring the gamma-ray sky for several years, enabling a search for powerful transients like gamma-ray bursts, novae, solar flares, and flaring active galactic nuclei, as well as long-term studies including pulsars, binary systems, supernova remnants, and searches for predicted sources of gamma rays such as dark matter annihilation. Some results include a stringent limit on Lorentz invariance derived from a gamma-ray burst, unexpected gamma-ray variability from the Crab Nebula, a huge ga.nuna-ray structure associated with the center of our galaxy, surprising behavior from some gamma-ray binary systems, and a possible constraint on some WIMP models for dark matter.

  17. Luminescence behavior of silicon and carbon nanoparticles dispersed in low-polar liquids

    PubMed Central

    2012-01-01

    A comparative photoluminescence analysis of as-prepared and chemically modified (by alkyl chains -C18H37) silicon and carbon nanoparticles dispersed in low-polar liquids is reported. Influence of the low-polar liquid nature and ambient temperature on photoluminescence of the nanoparticles has been investigated from the point of view of their possible application as thermal nanoprobes. PMID:22748140

  18. Heterogeneous Structure, Heterogeneous Dynamics, and Complex Behavior in Two-Dimensional Liquids.

    PubMed

    Patashinski, A Z; Ratner, M A; Grzybowski, B A; Orlik, R; Mitus, A C

    2012-09-01

    Analysis of the metrical and topological features of the local structure in a freezing two-dimensional Lennard-Jones system found that in a narrow strip [Formula: see text] of thermodynamic states close to the melting line, the liquid becomes a complex liquid characterized by a super-Arrhenius increase of relaxation times, stretched-exponential decay of correlations in time, and a power-law distribution of waiting times for changes in the local order. In [Formula: see text], the structure of the liquid and its dynamics are spatially heterogeneous; the sizes of ordered clusters are power-law distributed. Those features are governed by local structure evolution between solid-like and liquid-like (disordered) patterns. The liquid inside the strip [Formula: see text] gives a unique opportunity to study how heterogeneous structure, dynamics and complexity are intertwined with each other on a microscopic level. PMID:26292128

  19. From ultracold Fermi Gases to Neutron Stars

    NASA Astrophysics Data System (ADS)

    Salomon, Christophe

    2012-02-01

    Ultracold dilute atomic gases can be considered as model systems to address some pending problem in Many-Body physics that occur in condensed matter systems, nuclear physics, and astrophysics. We have developed a general method to probe with high precision the thermodynamics of locally homogeneous ultracold Bose and Fermi gases [1,2,3]. This method allows stringent tests of recent many-body theories. For attractive spin 1/2 fermions with tunable interaction (^6Li), we will show that the gas thermodynamic properties can continuously change from those of weakly interacting Cooper pairs described by Bardeen-Cooper-Schrieffer theory to those of strongly bound molecules undergoing Bose-Einstein condensation. First, we focus on the finite-temperature Equation of State (EoS) of the unpolarized unitary gas. Surprisingly, the low-temperature properties of the strongly interacting normal phase are well described by Fermi liquid theory [3] and we localize the superfluid phase transition. A detailed comparison with theories including recent Monte-Carlo calculations will be presented. Moving away from the unitary gas, the Lee-Huang-Yang and Lee-Yang beyond-mean-field corrections for low density bosonic and fermionic superfluids are quantitatively measured for the first time. Despite orders of magnitude difference in density and temperature, our equation of state can be used to describe low density neutron matter such as the outer shell of neutron stars. [4pt] [1] S. Nascimbène, N. Navon, K. Jiang, F. Chevy, and C. Salomon, Nature 463, 1057 (2010) [0pt] [2] N. Navon, S. Nascimbène, F. Chevy, and C. Salomon, Science 328, 729 (2010) [0pt] [3] S. Nascimbène, N. Navon, S. Pilati, F. Chevy, S. Giorgini, A. Georges, and C. Salomon, Phys. Rev. Lett. 106, 215303 (2011)

  20. Aggregation Behavior of Imidazolium-Based Surface-Active Ionic Liquids with Photoresponsive Cinnamate Counterions in the Aqueous Solution.

    PubMed

    Bi, Yanhui; Zhao, Liuchen; Hu, Qiongzheng; Gao, Yan'an; Yu, Li

    2015-11-24

    Two imidazolium-based surface active ionic liquids (SAILs) with photoresponsive cinnamate aromatic counterions, viz. 1-dodecyl-3-methylimidazolium cinnamate ([C12mim][CA]) and 1-dodecyl-3-methylimidazolium para-hydroxy-cinnamate ([C12mim][PCA]), were newly synthesized, and their self-assembly behaviors in aqueous solutions were systematically explored. Results of surface tension and conductivity measurements show that both [C12mim][CA] and [C12mim][PCA] display a superior surface activity in aqueous solutions compared to the common imidazolium-based SAIL, 1-dodecyl-3-methylimidazolium bromide (C12mimBr), which implies the incorporation of cinnamate aromatic counterions can promote the micellar formation. Furthermore, [C12mim][CA] shows higher surface activity due to the higher hydrophobicity of its counterion in comparison to [C12mim][PCA] that has a hydroxyl group. Both hexagonal liquid-crystalline phase (H1) and cubic liquid-crystalline phase (V2) were constructed in the [C12mim][CA] aqueous solutions. In contrast, the [C12mim][PCA]/H2O system only exhibits a single hexagonal liquid-crystalline phase (H1) in a broad concentration region. These lyotropic liquid crystal (LLC) phases were comprehensively characterized by polarized optical microscopy (POM), small-angle X-ray scattering (SAXS), and rheometer. Investigation on the temperature-dependent self-assembly nanostructures demonstrates that the higher temperature leads to a looser arrangement. Under UV irradiation, trans-cis photoisomerization of the phenylalkene group results in inferior surface activity of the prepared SAILs in aqueous solution with higher cmc values. Moreover, UV light irradiation induces obvious change of the structural parameters without altering the LLC phases. This work is expected to enrich the investigations of phase behaviors formed in SAILs systems and receive particular attention due to their unique properties and potential applications in drug delivery, biochemistry, materials

  1. Some aspects of singular interactions in condensed Fermi systems

    NASA Astrophysics Data System (ADS)

    Stamp, P. C. E.

    1993-02-01

    This article gives a fairly detailed survey of some of the problems raised when the interaction energy f^{σ σ'}_{k k'} between 2 fermionic quasiparticles (in 2 dimensions) is singular when |k-k'|to 0. Before dealing with singular interactions, it is shown how a non-singular f^{σ σ'}_{k k'} leads to a 2-dimensional Fermi liquid theory, which is internally consistent, at least as far as its infrared properties are concerned. The quasiparticle properties are calculated in detail. The question of whether singular interactions arise for the dilute Fermi gas, with short-range repulsive interactions, is investigated perturbatively. One finds a weak singularity in f^{σ σ'}_{k k'}, when the dimensionality D = 2, but it does not destabilize the Fermi liquid. A more sophisticated analysis is then given, to all orders in the interaction, using the Lippman-Schwinger equation as well as a phase shift analysis for a finite box. The conclusion is that any breakdown of Fermi liquid theory must come from non-perturbative effects. An examination is then made of some of the consequences arising if a singular interaction is introduced — the form proposed by Anderson is used as an example. A hierarchy of singular terms arise in all quantities — this is shown for the self-energy, and also the 3 point and 4 point scattering functions. These may be summed in a perfectly consistent manner. Most attention is given to the particle-hole channel, since it appears to lead to results different from those of Anderson. Nevertheless it appears that it is possible to derive a sensible theory starting from a singular effective Hamiltonian — although Fermi Liquid theory breaks down, all fermionic quantities may be calculated consistently. Finally, the effect of a magnetic field (which cuts off the infrared divergences) is investigated, and the de Haas-van Alphen amplitude calculated, for such a singular Fermionic system.

  2. Fermi resonance in optical microcavities.

    PubMed

    Yi, Chang-Hwan; Yu, Hyeon-Hye; Lee, Ji-Won; Kim, Chil-Min

    2015-04-01

    Fermi resonance is a phenomenon of quantum mechanical superposition, which most often occurs between normal and overtone modes in molecular systems that are nearly coincident in energy. We find that scarred resonances in deformed dielectric microcavities are the very phenomenon of Fermi resonance, that is, a pair of quasinormal modes interact with each other due to coupling and a pair of resonances are generated through an avoided resonance crossing. Then the quantum number difference of a pair of quasinormal modes, which is a consequence of quantum mechanical superposition, equals periodic orbits, whereby the resonances are localized on the periodic orbits. We derive the relation between the quantum number difference and the periodic orbits and confirm it in an elliptic, a rectangular, and a stadium-shaped dielectric microcavity.

  3. Transients with the Fermi GBM

    NASA Astrophysics Data System (ADS)

    Hui, Michelle; Fermi GBM Team

    2016-03-01

    The Fermi Gamma-ray Burst Monitor (GBM) is an all-sky monitoring instrument sensitive to energies from 8 keV to 40 MeV. Its primary science objective is observing gamma-ray bursts (GRBs) in support of the Large Area Telescope, which are both part of the Fermi Gamma-ray Space Telescope. Over the past 7 years of operation, the GBM has detected over 240 GRBs per year and provided timely GCN notices for follow-up observations. In addition to GRBs, Galactic transients, solar flares, and terrestrial gamma-ray flashes have also been observed. With several instruments coming online recently, such as the gravitational wave detectors Advanced LIGO/Virgo and the very high energy surveying instrument HAWC, now is an opportune time for multi-messenger collaboration in counterpart search of gravitational waves and GRBs.

  4. BEHAVIOR OF SURFACTANT MIXTURES AT SOLID/LIQUID AND OIL/LIQUID INTERFACES IN CHEMICAL FLOODING SYSTEMS

    SciTech Connect

    P. Somasundaran

    2004-11-20

    The aim of the project is to develop a knowledge base to help the design of enhanced processes for mobilizing and extracting untrapped oil. We emphasize evaluation of novel surfactant mixtures and obtaining optimum combinations of the surfactants for efficient chemical flooding EOR processes. In this regard, an understanding of the aggregate shape, size and structure is crucial since these properties govern the crude oil removal efficiency. During the three-year period, the adsorption and aggregation behavior of sugar-based surfactants and their mixtures with other types of surfactants have been studied. Sugar-based surfactants are made from renewable resources, nontoxic and biodegradable. They are miscible with water and oil. These environmentally benign surfactants feature high surface activity, good salinity, calcium and temperature tolerance, and unique adsorption behavior. They possess the characteristics required for oil flooding surfactants and have the potential for replacing currently used surfactants in oil recovery. A novel analytical ultracentrifugation technique has been successfully employed for the first time, to characterize the aggregate species present in mixed micellar solution due to its powerful ability to separate particles based on their size and shape and monitor them simultaneously. Analytical ultracentrifugation offers an unprecedented opportunity to obtain important information on mixed micelles, structure-performance relationship for different surfactant aggregates in solution and their role in interfacial processes. Initial sedimentation velocity investigations were conducted using nonyl phenol ethoxylated decyl ether (NP-10) to choose the best analytical protocol, calculate the partial specific volume and obtain information on sedimentation coefficient, aggregation mass of micelles. Four softwares: OptimaTM XL-A/XL-I data analysis software, DCDT+, Svedberg and SEDFIT, were compared for the analysis of sedimentation velocity

  5. Fermi Timing and Synchronization System

    SciTech Connect

    Wilcox, R.; Staples, J.; Doolittle, L.; Byrd, J.; Ratti, A.; Kaertner, F.X.; Kim, J.; Chen, J.; Ilday, F.O.; Ludwig, F.; Winter, A.; Ferianis, M.; Danailov, M.; D'Auria, G.

    2006-07-19

    The Fermi FEL will depend critically on precise timing of its RF, laser and diagnostic subsystems. The timing subsystem to coordinate these functions will need to reliably maintain sub-100fs synchronicity between distant points up to 300m apart in the Fermi facility. The technology to do this is not commercially available, and has not been experimentally demonstrated in a working facility. Therefore, new technology must be developed to meet these needs. Two approaches have been researched by different groups working with the Fermi staff. At MIT, a pulse transmission scheme has been developed for synchronization of RF and laser devices. And at LBL, a CW transmission scheme has been developed for RF and laser synchronization. These respective schemes have advantages and disadvantages that will become better understood in coming years. This document presents the work done by both teams, and suggests a possible system design which integrates them both. The integrated system design provides an example of how choices can be made between the different approaches without significantly changing the basic infrastructure of the system. Overall system issues common to any synchronization scheme are also discussed.

  6. Enrico Fermi and the Dolomites

    NASA Astrophysics Data System (ADS)

    Battimelli, Giovanni; de Angelis, Alessandro

    2014-11-01

    Summer vacations in the Dolomites were a tradition among the professors of the Faculty of Mathematical and Physical Sciences at the University of Roma since the end of the XIX century. Beyond the academic walls, people like Tullio Levi-Civita, Federigo Enriques and Ugo Amaldi sr., together with their families, were meeting friends and colleagues in Cortina, San Vito, Dobbiaco, Vigo di Fassa and Selva, enjoying trekking together with scientific discussions. The tradition was transmitted to the next generations, in particular in the first half of the XX century, and the group of via Panisperna was directly connected: Edoardo Amaldi, the son of the mathematician Ugo sr., rented at least during two summers, in 1925 and in 1949, and in the winter of 1960, a house in San Vito di Cadore, and almost every year in the Dolomites; Enrico Fermi was a frequent guest. Many important steps in modern physics, in particular the development of the Fermi-Dirac statistics and the Fermi theory of beta decay, are related to scientific discussions held in the region of the Dolomites.

  7. Dipole Polarizability of a Trapped Superfluid Fermi Gas

    SciTech Connect

    Recati, A.; Carusotto, I.; Lobo, C.; Stringari, S.

    2006-11-10

    The polarization produced by the relative displacement of the potentials trapping two spin species of a dilute Fermi gas with N{sub {up_arrow}}=N{sub {down_arrow}} is calculated at unitarity by assuming phase separation between the superfluid and a polarized phase at zero temperature. Because of the energy cost associated with pair breaking, the dipole polarizability is strongly quenched and exhibits important deviations from the ideal gas behavior even for nonlinear displacements of the order of the size of the atomic cloud. The behavior in the presence of different trapping frequencies (monopole polarization) for the two spin species is also discussed. Our results suggest new experimental perspectives to explore the quantum phases of interacting Fermi gases.

  8. Giant spin oscillations in an ultracold Fermi sea.

    PubMed

    Krauser, J S; Ebling, U; Fläschner, N; Heinze, J; Sengstock, K; Lewenstein, M; Eckardt, A; Becker, C

    2014-01-10

    Collective behavior in many-body systems is the origin of many fascinating phenomena in nature, ranging from the formation of clouds to magnetic properties of solids. We report on the observation of collective spin dynamics in an ultracold Fermi sea with large spin. As a key result, we observed long-lived and large-amplitude coherent spin oscillations driven by local spin interactions. At ultralow temperatures, Pauli blocking stabilizes the collective behavior, and the Fermi sea behaves as a single entity in spin space. With increasing temperature, we observed a stronger damping associated with particle-hole excitations. Unexpectedly, we found a high-density regime where excited spin configurations are collisionally stabilized. Our results reveal the intriguing interplay between microscopic processes either stimulating or suppressing collective effects in a fermionic many-body system.

  9. Heat capacity and sound velocities of low dimensional Fermi gases

    NASA Astrophysics Data System (ADS)

    Salas, P.; Solis, M. A.

    2014-03-01

    We report the heat capacity ratio and sound velocities for an interactionless Fermi gas immersed in periodic structures such as penetrable multilayers or multitubes created by one (planes) or two perpendicular (tubes) external Dirac comb potentials. The isobaric specific heat of the fermion gas presents the dimensional crossover previously observed in the isochoric specific heat - from 3D to 2D or to 1D -. The quotient between the two quantities has a prominent bump related to the confinement, and as the temperature increases, it goes towards the monoatomic classical gas value 5/3. We present the isothermal and the adiabatic sound velocities of the fermion gas which show anomalous behavior at temperatures below TF due to the dimensionality of the system, while at higher temperatures again we recover the behavior of a classical Fermi gas. Furthermore, as the temperature goes to zero the sound velocity has a finite value, as expected.

  10. A Fermi gas in a homogeneous box potential

    NASA Astrophysics Data System (ADS)

    Mukherjee, Biswaroop; Ku, Mark; Yan, Zhenjie; Patel, Parth; Guardado-Sanchez, Elmer; Yefsah, Tarik; Struck, Julian; Zwierlein, Martin; Zwierlein Group Team

    2015-05-01

    Traditionally, bulk quantum gas experiments take place in inhomogeneous optical and/or magnetic traps. The properties of the homogeneous gas are in many cases masked by line-of-sight integration over the inhomogeneous sample. We report on the trapping of strongly interacting fermionic atoms (6Li) in a quasi-homogenous all-optical potential. We characterize the potential flatness through in-trap imaging, and discuss progress towards directly observing the momentum distribution of the fermions in a box, with the prospect to test predictions from Fermi liquid theory for interacting gases. In contrast to inhomogeneous traps, box potentials prepare a system in one particular point of the phase diagram, giving access to the properties of bulk matter with a high signal-to-noise ratio. This sets a new direction for the exploration of strongly interacting Fermi gases at finite temperature and in the presence of spin imbalance.

  11. Thermoresponsive Poly(Ionic Liquid)s in Aqueous Salt Solutions: Salting-Out Effect on Their Phase Behavior and Water Absorption/Desorption Properties.

    PubMed

    Okafuji, Akiyoshi; Kohno, Yuki; Ohno, Hiroyuki

    2016-07-01

    Here, a thermoresponsive phase behavior of polymerized ionic liquids (PILs) composed of poly([tri-n-alkyl(vinylbenzyl)phosphonium]chloride) (poly([Pnnn VB ]Cl) is reported, where n (the number of carbon atoms of an alkyl chain) = 4, 5, or 6 after mixing with aqueous sodium chloride solutions. Both monomeric [P555VB ]Cl and the resulting poly([P555VB ]Cl) linear homopolymer show a lower critical solution temperature (LCST)-type phase behavior in aq. NaCl solutions. The phase transition temperature of the PIL shifts to lower value by increasing concentration of NaCl. Also the swelling degree of cross-linked poly([P555VB ]Cl) gel decreases by increasing NaCl concentration, clearly suggesting the "salting-out" effect of NaCl results in a significant dehydration of the poly([P555VB ]Cl) gel. The absorbed water in the PIL gel is desorbed by moderate heating via the LCST behavior, and the absolute absorption/desorption amount is improved by copolymerization of [P555VB ]Cl with more hydrophilic [P444VB ]Cl monomer.

  12. Thermoresponsive Poly(Ionic Liquid)s in Aqueous Salt Solutions: Salting-Out Effect on Their Phase Behavior and Water Absorption/Desorption Properties.

    PubMed

    Okafuji, Akiyoshi; Kohno, Yuki; Ohno, Hiroyuki

    2016-07-01

    Here, a thermoresponsive phase behavior of polymerized ionic liquids (PILs) composed of poly([tri-n-alkyl(vinylbenzyl)phosphonium]chloride) (poly([Pnnn VB ]Cl) is reported, where n (the number of carbon atoms of an alkyl chain) = 4, 5, or 6 after mixing with aqueous sodium chloride solutions. Both monomeric [P555VB ]Cl and the resulting poly([P555VB ]Cl) linear homopolymer show a lower critical solution temperature (LCST)-type phase behavior in aq. NaCl solutions. The phase transition temperature of the PIL shifts to lower value by increasing concentration of NaCl. Also the swelling degree of cross-linked poly([P555VB ]Cl) gel decreases by increasing NaCl concentration, clearly suggesting the "salting-out" effect of NaCl results in a significant dehydration of the poly([P555VB ]Cl) gel. The absorbed water in the PIL gel is desorbed by moderate heating via the LCST behavior, and the absolute absorption/desorption amount is improved by copolymerization of [P555VB ]Cl with more hydrophilic [P444VB ]Cl monomer. PMID:26987760

  13. Complex dendrimer-lyotropic liquid crystalline systems: structural behavior and interactions.

    PubMed

    Bitan-Cherbakovsky, Liron; Libster, Dima; Aserin, Abraham; Garti, Nissim

    2011-10-27

    The incorporation of dendrimer into three lyotropic liquid crystalline (LLCs) mesophases is demonstrated for the first time. A second generation (G2) of poly(propylene imine) dendrimer (PPI) was solubilized into lamellar, diamond reverse cubic, and reverse hexagonal LLCs composed of glycerol monooleate (GMO), and water (and D-α-tocopherol in the H(II) system). The combination of PPI with LLCs may provide an advantageous drug delivery system. Cross-polarized light microscope, small-angle X-ray scattering (SAXS), and attenuated total reflectance Fourier transform infrared (ATR-FTIR) were utilized to study the structural behavior of the mesophases, the localization of PPI within the system, and the interactions between the guest molecule and the system's components. It was revealed that PPI-G2 functioned as a "water pump", competing with the lipid headgroups for water binding. As a result, L(α)→H(II) and Q(224)→H(II) structural shifts were detected (at 10 wt % PPI-G2 content), probably caused by the dehydration of monoolein headgroups and subsequent increase of the lipid's critical packing parameter (CPP). In the case of H(II), as a result of the balance between the dehydration of the monoolein headgroups and the significant presence of PPI within the interfacial region, increasing the quantity of hydrogen bonds, no structural transitions occurred. ATR-FTIR analysis demonstrated a downward shift of the H-O-H (water), as a result of PPI-G2 embedment, suggesting an increase in the mean water-water H-bond angle resulting from binding PPI-G2 to the water network. Additionally, the GMO hydroxyl groups at β- and γ-C-OH positions revealed a partial interaction of hydrogen bonds with N-H functional groups of the protonated PPI-G2. Other GMO interfacial functional groups were shown to interact with the PPI-G2, in parallel with the GMO dehydration phenomenon. In the future, these outcomes can be used to design advanced drug delivery systems, allowing administration of

  14. Complex dendrimer-lyotropic liquid crystalline systems: structural behavior and interactions.

    PubMed

    Bitan-Cherbakovsky, Liron; Libster, Dima; Aserin, Abraham; Garti, Nissim

    2011-10-27

    The incorporation of dendrimer into three lyotropic liquid crystalline (LLCs) mesophases is demonstrated for the first time. A second generation (G2) of poly(propylene imine) dendrimer (PPI) was solubilized into lamellar, diamond reverse cubic, and reverse hexagonal LLCs composed of glycerol monooleate (GMO), and water (and D-α-tocopherol in the H(II) system). The combination of PPI with LLCs may provide an advantageous drug delivery system. Cross-polarized light microscope, small-angle X-ray scattering (SAXS), and attenuated total reflectance Fourier transform infrared (ATR-FTIR) were utilized to study the structural behavior of the mesophases, the localization of PPI within the system, and the interactions between the guest molecule and the system's components. It was revealed that PPI-G2 functioned as a "water pump", competing with the lipid headgroups for water binding. As a result, L(α)→H(II) and Q(224)→H(II) structural shifts were detected (at 10 wt % PPI-G2 content), probably caused by the dehydration of monoolein headgroups and subsequent increase of the lipid's critical packing parameter (CPP). In the case of H(II), as a result of the balance between the dehydration of the monoolein headgroups and the significant presence of PPI within the interfacial region, increasing the quantity of hydrogen bonds, no structural transitions occurred. ATR-FTIR analysis demonstrated a downward shift of the H-O-H (water), as a result of PPI-G2 embedment, suggesting an increase in the mean water-water H-bond angle resulting from binding PPI-G2 to the water network. Additionally, the GMO hydroxyl groups at β- and γ-C-OH positions revealed a partial interaction of hydrogen bonds with N-H functional groups of the protonated PPI-G2. Other GMO interfacial functional groups were shown to interact with the PPI-G2, in parallel with the GMO dehydration phenomenon. In the future, these outcomes can be used to design advanced drug delivery systems, allowing administration of

  15. Superradiant phase transition of Fermi gases in a cavity across a Feshbach resonance

    NASA Astrophysics Data System (ADS)

    Chen, Yu; Zhai, Hui; Yu, Zhenhua

    2015-02-01

    We consider the superradiant phase transition of a two-component Fermi gas in a cavity across a Feshbach resonance. It is known that quantum statistics plays a crucial role for the superradiant phase transition in atomic gases; in contrast to bosons, in a Fermi gas this transition exhibits strong density dependence. We show that across a Feshbach resonance, while the two-component Fermi gas passes through the BEC-BCS crossover, the superradiant phase transition undergoes a corresponding crossover from a fermionic behavior on the weakly interacting BCS side, to a bosonic behavior on the molecular Bose-Einstein condensate (BEC) side. This intricate statistics crossover makes the superradiance maximally enhanced either in the unitary regime for low densities, in the BCS regime for moderate densities close to Fermi surface nesting, or in the BEC regime for high densities.

  16. Communication: High pressure specific heat spectroscopy reveals simple relaxation behavior of glass forming molecular liquid.

    PubMed

    Roed, Lisa Anita; Niss, Kristine; Jakobsen, Bo

    2015-12-14

    The frequency dependent specific heat has been measured under pressure for the molecular glass forming liquid 5-polyphenyl-4-ether in the viscous regime close to the glass transition. The temperature and pressure dependences of the characteristic time scale associated with the specific heat is compared to the equivalent time scale from dielectric spectroscopy performed under identical conditions. It is shown that the ratio between the two time scales is independent of both temperature and pressure. This observation is non-trivial and demonstrates the existence of specially simple molecular liquids in which different physical relaxation processes are both as function of temperature and pressure/density governed by the same underlying "inner clock." Furthermore, the results are discussed in terms of the recent conjecture that van der Waals liquids, like the measured liquid, comply to the isomorph theory.

  17. Influence of interspecific competition on the recruitment behavior and liquid food transport in the tramp ant species Pheidole megacephala

    NASA Astrophysics Data System (ADS)

    Dejean, Alain; Breton, Julien; Suzzoni, Jean Pierre; Orivel, Jérôme; Saux-Moreau, Corrie

    2005-07-01

    This study was conducted on the reactions of Pheidole megacephala scouts when finding liquid food sources situated on territories marked by competing dominant ant species or on unmarked, control areas to see if the number of recruited nestmates is affected and if soldiers behave in ways adapted to the situation. We show that scouts recruit more nestmates, particularly soldiers, on marked rather than on unmarked areas. This recruitment allows P. megacephala to organize the defence and rapid depletion of these food sources prior to any contact with competitors. Soldiers can carry liquid foods both (1) in their crops like other Myrmicinae and (2), in a new finding concerning myrmicine ants, under their heads and thoraxes like certain poneromorph genera because the droplets adhere through surface tension strengths. Later, the liquids stored in the crop are distributed to nestmates through regurgitations during trophallaxis and the external droplets are distributed through “social buckets”, or the mode of liquid food transfer common in poneromorphs. Their flexibility to use or not use the latter technique, based on the situation, corroborates other reports that Pheidole soldiers have a relatively large behavioral repertoire.

  18. Unusual Interfacial Phase Behavior of Two Nonmiscible Liquids in a Cylindrical Test Tube: Equilibrium Shapes and Stability of Axisymmetric Liquid Bridges under Gravity.

    PubMed

    Ligoure

    2000-03-15

    In this paper the unusual interfacial phase behavior of two nonmiscible fluids contained in a cylindrical glass test tube is reported. Water, which is the lighter phase, takes up the upper part of the tube, whereas the denser compound (a hydrofluorocarbon) is in the bottom. However, below some critical volume of water, the denser phase emerges at the air surface, by forming an axisymmetric liquid bridge through the aqueous phase. Above the critical condition, the formation of the bridge, the evolution of the shape of this bridge, and its final breakdown can be visually inspected after shaking the tube. The minority liquid (water) is dispersed in the majority phase (HCFC) as an unstable dispersion of droplets. Droplets rise to the air surface under the action of the buoyant force, and coalesce on the glass wall: this leads to the formation of a bridge (made from the dispersion in the middle of a hollow axisymmetric water drop), whose height increases and thickness decreases during the coalescence process, until it breaks down. Using a free energy analysis, we state the exact variational problem via its Euler-Lagrange equation. However, since this nonlinear differential equation cannot be solved analytically, a simplified "mean-field" approach is developed, which provides a comprehensive insight into the physical origin of these capillary bridges and their stability under gravity. Copyright 2000 Academic Press. PMID:10700402

  19. Animating Fermi - Science Outreach through Art

    NASA Astrophysics Data System (ADS)

    Corbet, Robin; Arcadias, Laurence

    2014-08-01

    Animation students at the Maryland Institute College of Art working with scientists in the Fermi team at the NASA Goddard Space Flight Center produced five short animations (and an associated game) related to science discoveries and operations of the Fermi satellite. The topics animated were the Fermi bubbles, dark matter, binary stars, the discovery of cosmic rays, and space debris. We describe the process, show examples of the animations, and discuss the potential of art/science collaborations for public outreach and education.

  20. Adaptive Optics with a Liquid-Crystal-on-Silicon Spatial Light Modulator and Its Behavior in Retinal Imaging

    NASA Astrophysics Data System (ADS)

    Shirai, Tomohiro; Takeno, Kohei; Arimoto, Hidenobu; Furukawa, Hiromitsu

    2009-07-01

    An adaptive optics system with a brand-new device of a liquid-crystal-on-silicon (LCOS) spatial light modulator (SLM) and its behavior in in vivo imaging of the human retina are described. We confirmed by experiments that closed-loop correction of ocular aberrations of the subject's eye was successfully achieved at the rate of 16.7 Hz in our system to obtain a clear retinal image in real time. The result suggests that an LCOS SLM is one of the promising candidates for a wavefront corrector in a prospective commercial ophthalmic instrument with adaptive optics.

  1. Synthetic strategy of porous ZnO and CdS nanostructures doped ferroelectric liquid crystal and its optical behavior

    NASA Astrophysics Data System (ADS)

    Pal, Kaushik; Maiti, Uday Narayan; Majumder, Tapas Pal; Debnath, Subhas Chandra; Bennis, Noureddine; Otón, Jose Manuel

    2013-03-01

    A simple and scalable chemical approach has been proposed for the generation of 1-dimensional nanostructures of two most important inorganic materials such as zinc oxide and cadmium sulfide. By controlling the growth habit of the nanostructures with manipulated reaction conditions, the diameter and uniformity of the nanowires/nanorods were tailored. We studied extensively optical behavior and structural growth of CdS NWs and ZnO NRs doped ferroelectric liquid crystal Felix-017/100. Due to doping band gap has been changed and several blue shifts occurred in photoluminescence spectra because of nanoconfinement effect and mobility of charges.

  2. Investigaction of Switching Behavior in a Ferroelectric Liquid Crystal Aligned on Obliquely Deposited SiO Films

    NASA Astrophysics Data System (ADS)

    Yamada, Yuichiro; Yamamoto, Norio; Inoue, Tetsuya; Orihara, Hiroshi; Ishibashi, Yoshihiro

    1989-01-01

    The effect of oblique evaporation of SiO on the chevron structure and the switching behavior in a ferroelectric liquid crystal have been investigated by means of the X-ray diffraction and the stroboscopic micrographs. It is found experimentally that the chevron direction and the domain structure appearing during the switching are determined by the direction of incidence of evaporated SiO. On the basis of the experimental results, it is clarified that the bow and the stern of the boat-shaped domain correspond to {+}2π and {-}2π internal disclinations, respectively. The structure of the zig-zag defect is determined.

  3. Photoresponsive Liquid Crystalline Epoxy Networks with Shape Memory Behavior and Dynamic Ester Bonds.

    PubMed

    Li, Yuzhan; Rios, Orlando; Keum, Jong K; Chen, Jihua; Kessler, Michael R

    2016-06-22

    Functional polymers are intelligent materials that can respond to a variety of external stimuli. However, these materials have not yet found widespread real world applications because of the difficulties in fabrication and the limited number of functional building blocks that can be incorporated into a material. Here, we demonstrate a simple route to incorporate three functional building blocks (azobenzene chromophores, liquid crystals, and dynamic covalent bonds) into an epoxy-based liquid crystalline network (LCN), in which an azobenzene-based epoxy monomer is polymerized with an aliphatic dicarboxylic acid to create exchangeable ester bonds that can be thermally activated. All three functional building blocks exhibited good compatibility, and the resulting materials exhibits various photomechanical, shape memory, and self-healing properties because of the azobenzene molecules, liquid crystals, and dynamic ester bonds, respectively.

  4. Metallic behavior and metal insulator transition of two-dimensional holes in gallium arsenide

    NASA Astrophysics Data System (ADS)

    Gao, Xuan

    This thesis is an investigation of the anomalous metallic behavior and metal-insulator transition (MIT) of low density two dimensional (2D) holes in gallium arsenide (GaAs) quantum well. The prevailing one parameter scaling theory of localization for disordered 2D Fermi liquids predicts an insulating ground state at zero magnetic field for small rs---the ratio of Coulomb interaction energy over the Fermi energy. On the other hand, metallic-like temperature (T) dependent transport has been observed in various high mobility Fermionic 2D systems with high rs. Exploring the electronic transport of high mobility hole gas in 2D GaAs quantum wells down to 10mKelvin temperature range, we find that weak localization or single particle quantum interference is greatly suppressed in both the temperature dependence of the resistance and the low field magnetoresistance. We observe that a parallel magnetic field B11 applied in the 2D plane does not affect T *, the temperature/energy scale of the metallic resistance drop of the system, although it suppresses the magnitude of the resistance drop. Furthermore, the temperature dependent conductivity of 2D holes in a strong B 11 agrees with the Coulomb interaction theory of a spin polarized Fermi liquid in both the diffusive (T < h/k Btau) and ballistic (T > h/ kBtau) transport regime, with r being the momentum relaxation time. Our transport data are consistent with the phase separation scenario. Driven by the competition between kinetic energy and Coulomb potential energy, the 2D hole liquid phase separates into a mixture of the localized 2D Fermi liquid phase and a metallic phase below T*. The 2D MIT at zero magnetic field in turn could be due to the localized Fermi liquid phase percolates through the metallic phase as disorder strength increases.

  5. Phase transitional behaviors of bent-cored liquid crystal in electric field

    NASA Astrophysics Data System (ADS)

    Peng, Huan-Gao; Zhou, Zicong; Merlitz, Holger; Wu, Chen-Xu

    2016-06-01

    Monte Carlo (MC) simulations based on lattice model were performed to study the phase diagram (anisotropy, uniaxiality and biaxiality) of liquid crystals formed by bent-cored molecules with a strong transverse dipole moment deviating from their angular bisector. It is shown that the asymmetric strong dipolar interaction enhances biaxiality slightly but encourages uniaxiality greatly and as a result suppresses the system's isotropic order, which is different from a system free from external field in that dipole moment increases biaxiality by suppressing the uniaxial and the isotropic orders simultaneously. It is also found that an external electric field encourages the biaxiality slightly but considerably enhances the uniaxiality of bent-cored liquid crystal.

  6. Amphiphilic dendritic peptides: Synthesis and behavior as an organogelator and liquid crystal.

    PubMed

    Gao, Baoxiang; Li, Hongxia; Xia, Defang; Sun, Sufang; Ba, Xinwu

    2011-02-11

    New amphiphilic dendritic peptides on dendritic polyaspartic acid were designed and synthesized. The organogel and liquid crystal properties of these amphiphilic dendritic peptides were fully studied by field-emission SEM, temperature dependent FT-IR, differential scanning calorimetry, polarization optical microscopy and X-ray diffraction experiments. Amphiphilic dendritic peptides G3 show good organogel properties with a minimum gelation concentration as low as 1 wt %. Furthermore, amphiphilic dendritic peptides G3 can form a hexagonal columnar liquid crystal assembly over a wide temperature range.

  7. Bioterrorism and the Fermi Paradox

    NASA Astrophysics Data System (ADS)

    Cooper, Joshua

    2013-04-01

    We proffer a contemporary solution to the so-called Fermi Paradox, which is concerned with conflict between Copernicanism and the apparent paucity of evidence for intelligent alien civilizations. In particular, we argue that every community of organisms that reaches its space-faring age will (1) almost immediately use its rocket-building computers to reverse-engineer its genetic chemistry and (2) self-destruct when some individual uses said technology to design an omnicidal pathogen. We discuss some of the possible approaches to prevention with regard to Homo sapiens' vulnerability to bioterrorism, particularly on a short-term basis.

  8. Numerical Investigation and Experimental Reproduction of Fermi Acceleration in Laboratory Scale

    NASA Astrophysics Data System (ADS)

    Zhou, M.; Zhai, C.

    2015-12-01

    Fermi acceleration is widely accepted as the mechanism to explain power law of cosmic ray spectrum. Now this mechanism has been developed to first order Fermi acceleration and second order Fermi acceleration. In first order Fermi acceleration, also known as diffusive shock acceleration, particles are confined around the shock through scattering and accelerated by repeatedly crossing shock front. In second order Fermi acceleration, particles gain energy through statistical collisions with interstellar clouds. In this proposed work, we plan to carefully study these two kinds of acceleration numerically and experimentally. We first consider a single relativistic particle and investigate how it gains energy in Fermi-Ulam model and shock wave acceleration model respectively. We investigate collective behavior of particles with different kinds of wall-oscillation functions and try to find an optimal one in terms of efficiency of acceleration. Then, we plan to go further and consider a group of particles statistically, during which we borrow the correct generalization of Maxwell's velocity distribution in special relativity and compare the results with those in cases where we simply use Maxwell-Boltzmann distribution. To this end, we try to provide a scheme to build an accelerator applying both laser technology and mirror effect in Laboratory to reproduce Fermi acceleration, which might be a promising source to obtain high energy particles and further study the mechanism of cosmic rays acceleration.

  9. Fermi acceleration in the randomized driven Lorentz gas and the Fermi-Ulam model.

    PubMed

    Karlis, A K; Papachristou, P K; Diakonos, F K; Constantoudis, V; Schmelcher, P

    2007-07-01

    Fermi acceleration of an ensemble of noninteracting particles evolving in a stochastic two-moving wall variant of the Fermi-Ulam model (FUM) and the phase randomized harmonically driven periodic Lorentz gas is investigated. As shown in [A. K. Karlis, P. K. Papachristou, F. K. Diakonos, V. Constantoudis, and P. Schmelcher, Phys. Rev. Lett. 97, 194102 (2006)], the static wall approximation, which ignores scatterer displacement upon collision, leads to a substantial underestimation of the mean energy gain per collision. In this paper, we clarify the mechanism leading to the increased acceleration. Furthermore, the recently introduced hopping wall approximation is generalized for application in the randomized driven Lorentz gas. Utilizing the hopping approximation the asymptotic probability distribution function of the particle velocity is derived. Moreover, it is shown that, for harmonic driving, scatterer displacement upon collision increases the acceleration in both the driven Lorentz gas and the FUM by the same amount. On the other hand, the investigation of a randomized FUM, comprising one fixed and one moving wall driven by a sawtooth force function, reveals that the presence of a particular asymmetry of the driving function leads to an increase of acceleration that is different from that gained when symmetrical force functions are considered, for all finite number of collisions. This fact helps open up the prospect of designing accelerator devices by combining driving laws with specific symmetries to acquire a desired acceleration behavior for the ensemble of particles.

  10. Behavior of Avirulent Yersinia pestis in Liquid Whole Egg as Affected by Antimicrobials and Thermal Pasteurization

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Yersinia spp. is a psychrotrophic bacterium that can grow at temperatures as low as minus two degrees Celsius, and is known to contaminate shell eggs in the United States and shell eggs and liquid egg in South America. A study was performed to determine the thermal sensitivity of avirulent Yersinia...

  11. Thin-thick coexistence behavior of 8CB liquid crystalline films on silicon.

    PubMed

    Garcia, R; Subashi, E; Fukuto, M

    2008-05-16

    The wetting behavior of thin films of 4-n-octyl-4'-cyanobiphenyl (8CB) on Si is investigated via optical and x-ray reflectivity measurement. An experimental phase diagram is obtained showing a broad thick-thin coexistence region spanning the bulk isotropic-to-nematic (T(IN)) and the nematic-to-smectic-A (T(NA)) temperatures. For Si surfaces with coverages between 47 and 72 +/- 3 nm, reentrant wetting behavior is observed twice as we increase the temperature, with separate coexistence behaviors near T(IN) and T(NA). For coverages less than 47 nm, however, the two coexistence behaviors merge into a single coexistence region. The observed thin-thick coexistence near the second-order NA transition is not anticipated by any previous theory or experiment. Nevertheless, the behavior of the thin and thick phases within the coexistence regions is consistent with this being an equilibrium phenomenon.

  12. Quadratic Fermi node in a 3D strongly correlated semimetal.

    PubMed

    Kondo, Takeshi; Nakayama, M; Chen, R; Ishikawa, J J; Moon, E-G; Yamamoto, T; Ota, Y; Malaeb, W; Kanai, H; Nakashima, Y; Ishida, Y; Yoshida, R; Yamamoto, H; Matsunami, M; Kimura, S; Inami, N; Ono, K; Kumigashira, H; Nakatsuji, S; Balents, L; Shin, S

    2015-12-07

    Strong spin-orbit coupling fosters exotic electronic states such as topological insulators and superconductors, but the combination of strong spin-orbit and strong electron-electron interactions is just beginning to be understood. Central to this emerging area are the 5d transition metal iridium oxides. Here, in the pyrochlore iridate Pr2Ir2O7, we identify a non-trivial state with a single-point Fermi node protected by cubic and time-reversal symmetries, using a combination of angle-resolved photoemission spectroscopy and first-principles calculations. Owing to its quadratic dispersion, the unique coincidence of four degenerate states at the Fermi energy, and strong Coulomb interactions, non-Fermi liquid behaviour is predicted, for which we observe some evidence. Our discovery implies that Pr2Ir2O7 is a parent state that can be manipulated to produce other strongly correlated topological phases, such as topological Mott insulator, Weyl semimetal, and quantum spin and anomalous Hall states.

  13. [The Effects of Complex of Benzoquinone on Fermi Resonance].

    PubMed

    Li, Shuai-peng; Zhang, Feng-qin; Jiang, Li-tong; Lin, Xiao-long; Jiang, Yong-heng; Zhang Liu-yang; Lin, Bo; Gu, Hao

    2015-07-01

    Fermi resonance phenomenon exists in simple compounds and it also widely exists in vibration spectra of complex. The complex can be formed by adding up simple compounds. As a result, the characteristic parameters of some parts of molecule will make changes, and the molecular spectra have a significant change along with it. Benzoquinone and proline in the solution form charge-transfer complex under certain conditions, but the spectra intensity is weak, our research uses Teflon liquid-core optical fiber technology to gain high quality resonance Raman spectra. We acquire Raman spectra of Benzoquinone and its complex in experiments, and analyze the characteristic parameters of Fermi resonance according to J. F. Bertran quantum theory. The results shows that, because of the formation of complex, Fermi resonance peak of C==0 bond shifts to high wavelength, the spectra intensity decreases, the frequency space increases, the coupling coefficient increases. The explanation is that, in the solution of complex, proline is donor, while benzoquinone is acceptor, the non-bonding electron of N atom which is belong to proline transfers to the pi anti-bonding orbital of benzoquinone, then n-pi* charge transfer complex is produced. That causes the change of molecular energy level, changes the Raman spectra. All these researches provide new idea and clue for spectral line certification and attribution of complex molecules, complexes and polymer. PMID:26717725

  14. Quadratic Fermi node in a 3D strongly correlated semimetal

    DOE PAGES

    Kondo, Takeshi; Nakayama, M.; Chen, R.; Ishikawa, J. J.; Moon, E. -G.; Yamamoto, T.; Ota, Y.; Malaeb, W.; Kanai, H.; Nakashima, Y.; et al

    2015-12-07

    We report that strong spin–orbit coupling fosters exotic electronic states such as topological insulators and superconductors, but the combination of strong spin–orbit and strong electron–electron interactions is just beginning to be understood. Central to this emerging area are the 5d transition metal iridium oxides. Here, in the pyrochlore iridate Pr2Ir2O7, we identify a non-trivial state with a single-point Fermi node protected by cubic and time-reversal symmetries, using a combination of angle-resolved photoemission spectroscopy and first-principles calculations. Owing to its quadratic dispersion, the unique coincidence of four degenerate states at the Fermi energy, and strong Coulomb interactions, non-Fermi liquid behaviour ismore » predicted, for which we observe some evidence. Lastly, our discovery implies that Pr2Ir2O7 is a parent state that can be manipulated to produce other strongly correlated topological phases, such as topological Mott insulator, Weyl semimetal, and quantum spin and anomalous Hall states.« less

  15. Quadratic Fermi node in a 3D strongly correlated semimetal

    SciTech Connect

    Kondo, Takeshi; Nakayama, M.; Chen, R.; Ishikawa, J. J.; Moon, E. -G.; Yamamoto, T.; Ota, Y.; Malaeb, W.; Kanai, H.; Nakashima, Y.; Ishida, Y.; Yoshida, R.; Yamamoto, H.; Matsunami, M.; Kimura, S.; Inami, N.; Ono, K.; Kumigashira, H.; Nakatsuji, S.; Balents, L.; Shin, S.

    2015-12-07

    We report that strong spin–orbit coupling fosters exotic electronic states such as topological insulators and superconductors, but the combination of strong spin–orbit and strong electron–electron interactions is just beginning to be understood. Central to this emerging area are the 5d transition metal iridium oxides. Here, in the pyrochlore iridate Pr2Ir2O7, we identify a non-trivial state with a single-point Fermi node protected by cubic and time-reversal symmetries, using a combination of angle-resolved photoemission spectroscopy and first-principles calculations. Owing to its quadratic dispersion, the unique coincidence of four degenerate states at the Fermi energy, and strong Coulomb interactions, non-Fermi liquid behaviour is predicted, for which we observe some evidence. Lastly, our discovery implies that Pr2Ir2O7 is a parent state that can be manipulated to produce other strongly correlated topological phases, such as topological Mott insulator, Weyl semimetal, and quantum spin and anomalous Hall states.

  16. Quadratic Fermi node in a 3D strongly correlated semimetal

    PubMed Central

    Kondo, Takeshi; Nakayama, M.; Chen, R.; Ishikawa, J. J.; Moon, E.-G.; Yamamoto, T.; Ota, Y.; Malaeb, W.; Kanai, H.; Nakashima, Y.; Ishida, Y.; Yoshida, R.; Yamamoto, H.; Matsunami, M.; Kimura, S.; Inami, N.; Ono, K.; Kumigashira, H.; Nakatsuji, S.; Balents, L.; Shin, S.

    2015-01-01

    Strong spin–orbit coupling fosters exotic electronic states such as topological insulators and superconductors, but the combination of strong spin–orbit and strong electron–electron interactions is just beginning to be understood. Central to this emerging area are the 5d transition metal iridium oxides. Here, in the pyrochlore iridate Pr2Ir2O7, we identify a non-trivial state with a single-point Fermi node protected by cubic and time-reversal symmetries, using a combination of angle-resolved photoemission spectroscopy and first-principles calculations. Owing to its quadratic dispersion, the unique coincidence of four degenerate states at the Fermi energy, and strong Coulomb interactions, non-Fermi liquid behaviour is predicted, for which we observe some evidence. Our discovery implies that Pr2Ir2O7 is a parent state that can be manipulated to produce other strongly correlated topological phases, such as topological Mott insulator, Weyl semimetal, and quantum spin and anomalous Hall states. PMID:26640114

  17. Numerical methods for the Poisson-Fermi equation in electrolytes

    NASA Astrophysics Data System (ADS)

    Liu, Jinn-Liang

    2013-08-01

    The Poisson-Fermi equation proposed by Bazant, Storey, and Kornyshev [Phys. Rev. Lett. 106 (2011) 046102] for ionic liquids is applied to and numerically studied for electrolytes and biological ion channels in three-dimensional space. This is a fourth-order nonlinear PDE that deals with both steric and correlation effects of all ions and solvent molecules involved in a model system. The Fermi distribution follows from classical lattice models of configurational entropy of finite size ions and solvent molecules and hence prevents the long and outstanding problem of unphysical divergence predicted by the Gouy-Chapman model at large potentials due to the Boltzmann distribution of point charges. The equation reduces to Poisson-Boltzmann if the correlation length vanishes. A simplified matched interface and boundary method exhibiting optimal convergence is first developed for this equation by using a gramicidin A channel model that illustrates challenging issues associated with the geometric singularities of molecular surfaces of channel proteins in realistic 3D simulations. Various numerical methods then follow to tackle a range of numerical problems concerning the fourth-order term, nonlinearity, stability, efficiency, and effectiveness. The most significant feature of the Poisson-Fermi equation, namely, its inclusion of steric and correlation effects, is demonstrated by showing good agreement with Monte Carlo simulation data for a charged wall model and an L type calcium channel model.

  18. Mechanical and optical behavior of a tunable liquid lens using a variable cross section membrane: modeling results

    NASA Astrophysics Data System (ADS)

    Flores-Bustamante, Mario C.; Rosete-Aguilar, Martha; Calixto, Sergio

    2016-03-01

    A lens containing a liquid medium and having at least one elastic membrane as one of its components is known as an elastic membrane lens (EML). The elastic membrane may have a constant or variable thickness. The optical properties of the EML change by modifying the profile of its elastic membrane(s). The EML formed of elastic constant thickness membrane(s) have been studied extensively. However, EML information using elastic membrane of variable thickness is limited. In this work, we present simulation results of the mechanical and optical behavior of two EML with variable thickness membranes (convex-plane membranes). The profile of its surfaces were modified by liquid medium volume increases. The model of the convex-plane membranes, as well as the simulation of its mechanical behavior, were performed using Solidworks® software; and surface's points of the deformed elastic lens were obtained. Experimental stress-strain data, obtained from a silicone rubber simple tensile test, according to ASTM D638 norm, were used in the simulation. Algebraic expressions, (Schwarzschild formula, up to four deformation coefficients, in a cylindrical coordinate system (r, z)), of the meridional profiles of the first and second surfaces of the deformed convex-plane membranes, were obtained using the results from Solidworks® and a program in the software Mathematica®. The optical performance of the EML was obtained by simulation using the software OSLO® and the algebraic expressions obtained in Mathematica®.

  19. Vibrational lifetime and Fermi resonance in polyatomic molecules

    NASA Astrophysics Data System (ADS)

    Fendt, A.; Fischer, S. F.; Kaiser, W.

    1981-05-01

    The energy decay of CH-stretching modes of the molecules CHCl 3 ,CH 2Cl 2, CH 3COCH 3, CH 3OH, and CH 3CH 2OH is measured in the liquid state. The observed lifetime very between 1.5 and 65 ps. A theoretical analysis points to the importance of Fermi resonance in the vibrational relaxation process. Quantitative comparison between theory and experiments is presented for the individual molecules. The strong variation of the lifetime for CH-stretching modes of various molecules may be understood if several effects are taken into account. First and most important is the influence of the Fermi resonances. Without the anharmonic mixing of the initial state, the overtone of the CH-bending modes and/or a higher order combination tone, one would predict lifetimes which are more than an order of magnitude longer than the observed lifetimes. This effect has been discussed earlier in detail for methylhalides by Zygan-Maus and Fischer [11] and, more recently, it has been incorporated in elaborate discussions for triatomic molecules like CO 2 by several authors [12]. A second factor to be considered for the interpretation is the rapi energy redistribution between different CH-stretching states was found theoretically to be faster than the further decay process by an order of magnitude [6, 11]. Experimentally, this effect was verified in this note for CH 2Cl 2 by the observation that the decay time was the same regardl whether the symmetric or the asymmetric CH-stretching mode was excited. This effect leads to a lengthening of the observed decay process. There is a bottleneck effect. Finally, we have shown that location and width of the final state are important parameters for the interpretation of the depopulatio lifetime. The empirical determination of these effects is not free of uncertainties. Very strong Fermi resonance can lead to rapid energy exchange during the exc process. In this case there is no bottleneck effect and it is difficult to detect the pathway of the energy

  20. Magnetar Observations in the Swift-Fermi/GBM Era

    NASA Technical Reports Server (NTRS)

    Kouveliotou, Chryssa

    2010-01-01

    NASA's Fermi Observatory was launched June 11, 2008; the Fermi Gamma Ray Burst Monitor (GBM) began normal operations on July 14, about a month after launch, when the trigger algorithms were enabled. Since then, and against all odds, GBM recorded over 600 bursts from 4 SGRs. Of these four sources, only one was an old magnetar: SGR J1806+20. SGR J0501+4516, was discovered with Swift and extensively monitored with GBM. A source originally classified as AXP 1E1547.0-5408 exhibited SGR-like bursting behavior and we reclassified it as SGR J1550-5418. Finally, GBM discovered SGR J0418+5729 on 2009 June. Finally, on March 2010, a third new magnetar was discovered with Swift, SGR J1833-0832. I report below on the current status of the field and on several results combining multi-satellite and ground-based data

  1. Quasi-one-dimensional quantum spin liquid in the Cu(C4H4N2)(NO3)2 insulator

    NASA Astrophysics Data System (ADS)

    Shaginyan, V. R.; Stephanovich, V. A.; Popov, K. G.; Kirichenko, E. V.

    2016-01-01

    We analyze measurements of the magnetization, differential susceptibility and specific heat of quasi-onedimensional insulator Cu(C4H4N2)(NO3)2 (CuPzN) subjected to magnetic fields. We show that the thermodynamic properties are defined by quantum spin liquid formed with spinons, with the magnetic field tuning the insulator CuPzN towards quantum critical point related to fermion condensation quantum phase transition (FCQPT) at which the spinon effective mass diverges kinematically. We show that the FCQPT concept permits to reveal and explain the scaling behavior of thermodynamic characteristics. For the first time, we construct the schematic T-H (temperature-magnetic field) phase diagram of CuPzN that contains Landau-Fermi-liquid, crossover and non-Fermi liquid parts, thus resembling that of heavy-fermion compounds.

  2. Observation of Coupled Vortex Lattices in a Mass-Imbalance Bose and Fermi Superfluid Mixture

    NASA Astrophysics Data System (ADS)

    Yao, Xing-Can; Chen, Hao-Ze; Wu, Yu-Ping; Liu, Xiang-Pei; Wang, Xiao-Qiong; Jiang, Xiao; Deng, Youjin; Chen, Yu-Ao; Pan, Jian-Wei

    2016-09-01

    Quantized vortices play an essential role in diverse superfluid phenomena. In a Bose-Fermi superfluid mixture, especially of two mass-imbalance species, such macroscopic quantum phenomena are particularly rich due to the interplay between the Bose and Fermi superfluidity. However, generating a Bose-Fermi two-species superfluid, producing coupled vortex lattices within, and further probing interspecies interaction effects remain challenging. Here, we experimentally realize a two-species superfluid with dilute gases of lithium-6 and potassium-41, having a mass ratio of about seven. By rotating the superfluid mixture, we simultaneously produce coupled vortex lattices of the two species and thus present a definitive visual evidence for the double superfluidity. Moreover, we report several unconventional behaviors, due to the Bose-Fermi interaction, on the formation and decay of two-species vortices.

  3. Two-dimensional Fermi surfaces in Kondo insulator SmB₆.

    PubMed

    Li, G; Xiang, Z; Yu, F; Asaba, T; Lawson, B; Cai, P; Tinsman, C; Berkley, A; Wolgast, S; Eo, Y S; Kim, Dae-Jeong; Kurdak, C; Allen, J W; Sun, K; Chen, X H; Wang, Y Y; Fisk, Z; Li, Lu

    2014-12-01

    In the Kondo insulator samarium hexaboride (SmB6), strong correlation and band hybridization lead to an insulating gap and a diverging resistance at low temperature. The resistance divergence ends at about 3 kelvin, a behavior that may arise from surface conductance. We used torque magnetometry to resolve the Fermi surface topology in this material. The observed oscillation patterns reveal two Fermi surfaces on the (100) surface plane and one Fermi surface on the (101) surface plane. The measured Fermi surface cross sections scale as the inverse cosine function of the magnetic field tilt angles, which demonstrates the two-dimensional nature of the conducting electronic states of SmB6. PMID:25477456

  4. Ionic conductance behavior of polymeric gel electrolyte containing ionic liquid mixed with magnesium salt

    NASA Astrophysics Data System (ADS)

    Morita, Masayuki; Shirai, Takahiro; Yoshimoto, Nobuko; Ishikawa, Masashi

    A new polymeric gel electrolyte system conducting magnesium ion has been proposed. The gel electrolytes consisted of poly(ethylene oxide)-modified polymethacrylate (PEO-PMA) dissolving ionic liquid mixed with magnesium salt, Mg[(CF 3SO 2) 2N] 2. The polymeric gel films were self-standing, transparent and flexible with enough mechanical strength. The ionic conductance and the electrochemical properties of the gel films were investigated. Thermal analysis results showed that the polymeric gel is homogeneous and amorphous over a wide temperature range. The highest conductivity, 1.1 × 10 -4 S cm -1 at room temperature (20 °C), was obtained for the polymeric gel containing 50 wt.% of the ionic liquid in which the content of the magnesium salt was 20 mol%. The dc polarization of a Pt/Mg cell using the polymeric gel electrolyte proved that the magnesium ion (Mg 2+) is mobile in the present polymeric system.

  5. Exploring the thermodynamics of a universal Fermi gas.

    PubMed

    Nascimbène, S; Navon, N; Jiang, K J; Chevy, F; Salomon, C

    2010-02-25

    One of the greatest challenges in modern physics is to understand the behaviour of an ensemble of strongly interacting particles. A class of quantum many-body systems (such as neutron star matter and cold Fermi gases) share the same universal thermodynamic properties when interactions reach the maximum effective value allowed by quantum mechanics, the so-called unitary limit. This makes it possible in principle to simulate some astrophysical phenomena inside the highly controlled environment of an atomic physics laboratory. Previous work on the thermodynamics of a two-component Fermi gas led to thermodynamic quantities averaged over the trap, making comparisons with many-body theories developed for uniform gases difficult. Here we develop a general experimental method that yields the equation of state of a uniform gas, as well as enabling a detailed comparison with existing theories. The precision of our equation of state leads to new physical insights into the unitary gas. For the unpolarized gas, we show that the low-temperature thermodynamics of the strongly interacting normal phase is well described by Fermi liquid theory, and we localize the superfluid transition. For a spin-polarized system, our equation of state at zero temperature has a 2 per cent accuracy and extends work on the phase diagram to a new regime of precision. We show in particular that, despite strong interactions, the normal phase behaves as a mixture of two ideal gases: a Fermi gas of bare majority atoms and a non-interacting gas of dressed quasi-particles, the fermionic polarons.

  6. Corrosion Behavior of SnO2-based Electrode Ceramics in Soda-lime Glass Liquid

    NASA Astrophysics Data System (ADS)

    Luo, Guoqiang; Shen, Qiang; Li, Qizhong; Zhang, Dongming; Wang, Chuanbin; Zhang, Lianmeng

    2011-10-01

    Dense SnO2-based electrode ceramics have extensive application prospect in glass electric-melting industry due to the excellent electrically-conductive and chemical property in high temperatures and oxidation environment. In this paper, dense SnO2-based electrode ceramics doped with MnO2 and Sb2O3 were prepared by pressureless sintering method and the corrosion rate in soda-lime glass liquid as well as the microstructure evolution was mainly investigated. The results suggested that SnO2-based ceramics had good corrosion resistance, and the minimum value was only 2.54×10-4 mm/h when MnO2 content is 1.0% and Sb2O3 content is 0.1%. Composition Elements of Glass liquid were detected in the grain boundary and some intergranular pores. It was found that SnO2 grains remained unchanged, whereas MnO2 was easily dissolved into molten glass liquid. SnO2-based electrode ceramics with dense structure and few amounts of additives had excellent corrosion resistance to the molten glass.

  7. Fermi surface of YBCO by DHVA

    SciTech Connect

    Smith, J.L.; Fowler, C.M.; Freeman, B.L.; Hults, W.L.; King, J.C.; Mueller, F.M.

    1991-01-01

    These proceedings demonstrate how far scientist have come in the last four years of high temperature superconductivity. Knowledge of the energy bands and Fermi surfaces from experiment has come rather late. Photoemission, first showed proof of the validity of the energy band calculations. Positron annihilation, presented by West, after a rough start, is now giving evidence of the Fermi surface. Both of these techniques involve electronic excitations and hence, although they show the Fermi surface, do not put as severe a constraint on various models for superconductivity as does the de Haas-van Alphen (dHvA) effect. This is a true measurement of the electronic ground state in an applied magnetic field where the frequency of oscillatory magnetization yields extremal cross-sectional areas of the Fermi surface. The authors have already reported some of their Fermi surface work at two conferences but present here discussion of several more important aspects of the work. 11 refs., 2 figs.

  8. Compressibility of liquid-metallic hydrogen

    NASA Astrophysics Data System (ADS)

    MacDonald, A. H.

    1983-05-01

    An expression for the compressibility κ of liquid-metallic hydrogen, derived within adiabatic and linear screening approximations, is presented. Terms in the expression for κ have been associated with Landau parameters of the two-component Fermi liquid. The compressibility found for the liquid state is much larger than the compressibility which would be expected in the solid state.

  9. Fermi acceleration of auroral particles.

    NASA Technical Reports Server (NTRS)

    Sharber, J. R.; Heikkila, W. J.

    1972-01-01

    Review of a number of nighttime acceleration mechanisms proposed in the literature for the role of producing the keV nighttime auroral-particle fluxes. Parallel electric fields are rejected for several reasons, but particularly because of the observed simultaneous precipitation of electrons and protons. Acceleration in the neutral sheet is inadequate for producing the particle energies, the observed field-aligned pitch-angle distribution at high latitudes, and the spectral hardening toward lower latitudes. Neutral point mechanisms, although often suggested in principle, have never been demonstrated satisfactorily in theory or in practice. Pitch-angle scattering from a trapped population produced by transverse adiabatic compression is also incapable of producing the field-aligned distribution. It is therefore suggested that longitudinal or Fermi acceleration, which results from the known magnetospheric convection, is the main nighttime auroral acceleration mechanism. The argument is supported by data obtained with the soft-particle spectrometer on Isis 1.

  10. Pair Excitations in Fermi Fluids

    NASA Astrophysics Data System (ADS)

    Böhm, Helga M.; Krotscheck, Eckhard; Schörkhuber, Karl; Springer, Josef

    2006-09-01

    We present a theory of multi-pair excitations in strongly interacting Fermi systems. Based on an equations-of-motion approach for time-dependent pair correlations it leads to a qualitatively new structure of the density-density response function. Our theory reduces to both, i) the "correlated" random-phase approximation (RPA) for fermions if the two-pair excitations are ignored, and ii) the correlated Brillouin-Wigner perturbation theory for bosons in the appropriate limit. The theory preserves the two first energy-weighted sum rules. A familiar problem of the standard RPA is that its zero-sound mode is energetically much higher than found in experiments. The popular cure of introducing an average effective mass in the Lindhard function violates sum rules and describes the physics incorrectly. We demonstrate that the inclusion of correlated pair excitations gives the correct dispersion. As in 4He, a modification of the effective mass is unnecessary also in 3He.

  11. Physico-Chemical Properties and Phase Behavior of the Ionic Liquid-β-Cyclodextrin Complexes

    PubMed Central

    Rogalski, Marek; Modaressi, Ali; Magri, Pierre; Mutelet, Fabrice; Grydziuszko, Aleksandra; Wlazło, Michał; Domańska, Urszula

    2013-01-01

    The solubility of β-cyclodextrin (β-CD) in ionic liquids (ILs) and the activity coefficients at infinite dilution ( γ13∞) of more than 20 solutes (alkanes, aromatic hydrocarbons, alcohols) were measured in four chosen ionic liquids, their mixtures with β-CD, and in the β-CD at high temperatures from 338 to 398 K using the inverse gas chromatography. The intermolecular interactions, inclusion complexes and the possible increasing of the solubility of β-CD in water using the IL are presented. The solubility of β-CD in ten chosen hydrophobic ILs at the temperature T = 423 K was detected. The solid-liquid phase diagrams (SLE) of {IL (1) + β-CD (2)} binary systems at the high mole fraction of the IL were measured for three systems (1-ethyl-3-methylimidazolium chloride, [EMIM][Cl], 1-ethyl-3-methylimidazolium bromide, [EMIM][Br]; and for 1-butyl-3-methylimidazolium chloride, [BMIM][Cl]). The eutectic points were determined at the high IL concentration for all binary systems. The intermolecular interaction and the possibility of inclusion complexes of the IL and/or solvents with β-CD were discussed. The infrared spectroscopy, IR was used for the description of the intermolecular interactions in the (β-CD + IL) systems. It was shown via the activity coefficients at infinite dilution results that the inclusion complexes are dependent on the temperature. The addition of β-CD to the IL does not improve the selectivity of the separation of the aliphatics from aromatics. PMID:23945559

  12. Photochemical switching behavior of azofunctionalized polymer liquid crystal/SiO{sub 2} composite photonic crystal

    SciTech Connect

    Moritsugu, M.; Kim, S. N.; Ogata, T.; Nonaka, T.; Kurihara, S.; Kubo, S.; Segawa, H.; Sato, O.

    2006-10-09

    A photochemically tunable photonic crystal was prepared by infiltrating azopolymer liquid crystal in a SiO{sub 2} inverse opal structure. The SiO{sub 2} inverse opal film obtained reflected a light corresponding to the periodicity as well as the refractive indices of the inverse opal structure. Linearly polarized light irradiation shifted the reflection band to longer wavelength more than 15 nm. This is caused by the formation of anisotropic molecular orientation of the azopolymer. The switched state was stable in the dark, and the reversible switching of the reflection band can be achieved by the linearly and circularly polarized light irradiations.

  13. Irreversible thermochromic behavior in gold and silver nanorod/polymeric ionic liquid nanocomposite films.

    PubMed

    Tollan, Christopher M; Marcilla, Rebeca; Pomposo, Jose A; Rodriguez, Javier; Aizpurua, Javier; Molina, Jon; Mecerreyes, David

    2009-02-01

    The novel application of gold and silver nanorods as irreversible thermochromic dyes in polymeric ionic liquid (PIL) nanocomposites is proposed here. These materials have been synthesized by anion exchange of an imidazolium-based PIL in a solution that also contained gold nanorods. This resulted in the entrapment of the nanoobjects within a solid polymer precipitate. In this article, the effect of the temperature was studied in relation to the change of shape and, consequently, color of the gold or silver nanorods within the films. For the nanocomposites studied here, a maximum of two visual thermochromic transitions was observed for gold nanorods and up to three transitions were observed for silver nanorods.

  14. Structural and Critical Behaviors of Ag Rough Films Deposited on Liquid Substrates

    NASA Astrophysics Data System (ADS)

    Ye, Gao-xiang; Feng, Chun-mu; Zhang, Qi-rui; Ge, Hong-liang; Zhang, Xuan-jia

    1996-10-01

    A new Ag rough film system, deposited on silicone oil surfaces by rf-magnetron sputtering method, has been fabricated. The chrysanthemum-like surface morphology at micron length scale is observed. It is proposed that the anomalous critical behavior mainly results from the relative shift between the Ag atom clusters and the substrate. The discussion of the deposition mechanism is also presented.

  15. Macroscopic behavior of ferrocholesteric liquid crystals and ferrocholesteric gels and elastomers.

    PubMed

    Brand, Helmut R; Fink, Alexander; Pleiner, Harald

    2015-06-01

    We study the influence of macroscopic chirality on the macroscopic properties of superparamagnetic liquid crystals and gels. Specifically we derive macroscopic dynamic equations for ferrocholesteric low molecular weight (LMW) liquid crystals and for ferrocholesteric gels and elastomers in the local description using the director field as macroscopic variable. The magnetization is treated as a macroscopic dynamic degree of freedom and its coupling to all other macroscopic variables is examined in detail. We incorporate into our dynamic analysis terms that are linear in a magnetic field giving rise to a number of cross-coupling terms not possible otherwise. A number of properties that are unique to the class of systems studied arise. As an example for a static property we find a term in the generalized energy which is linear in the electric field and quadratic in the magnetic field. We find that applying a magnetic field to a ferrocholesteric can lead to reversible electric currents, heat currents and concentration currents, which change their sign with a sign change of macroscopic chirality. As an example of a rather intriguing dissipative dynamic contribution we point out that for ferrocholesterics and for ferrocholesteric gels and elastomers in a magnetic field extensional flow leads to electric and heat currents.

  16. Li-Doped Ionic Liquid Electrolytes: From Bulk Phase to Interfacial Behavior

    NASA Technical Reports Server (NTRS)

    Haskins, Justin B.; Lawson, John W.

    2016-01-01

    Ionic liquids have been proposed as candidate electrolytes for high-energy density, rechargeable batteries. We present an extensive computational analysis supported by experimental comparisons of the bulk and interfacial properties of a representative set of these electrolytes as a function of Li-salt doping. We begin by investigating the bulk electrolyte using quantum chemistry and ab initio molecular dynamics to elucidate the solvation structure of Li(+). MD simulations using the polarizable force field of Borodin and coworkers were then performed, from which we obtain an array of thermodynamic and transport properties. Excellent agreement is found with experiments for diffusion, ionic conductivity, and viscosity. Combining MD simulations with electronic structure computations, we computed the electrochemical window of the electrolytes across a range of Li(+)-doping levels and comment on the role of the liquid environment. Finally, we performed a suite of simulations of these Li-doped electrolytes at ideal electrified interfaces to evaluate the differential capacitance and the equilibrium Li(+) distribution in the double layer. The magnitude of differential capacitance is in good agreement with our experiments and exhibits the characteristic camel-shaped profile. In addition, the simulations reveal Li(+) to be highly localized to the second molecular layer of the double layer, which is supported by additional computations that find this layer to be a free energy minimum with respect to Li(+) translation.

  17. Behavior of Spinning Space Vehicles with Onboard Liquids, 2nd Edition, Technical Report B8030

    NASA Technical Reports Server (NTRS)

    Hubert, Carl

    2008-01-01

    Although the fundamental principles of spin stabilization are well established, uncertainty regarding the potential for rapid nutation growth caused by onboard liquids is a continuing concern. NASA and other organizations regularly encounter the issue of rapid nutation growth due to energy dissipation by liquids on spinning vehicles. Of concern is the stability of spinning upper stages and of spacecraft that spin for part or all of their missions. Several missions have required last-minute hardware or operational changes to deal with rapid nutation divergences that were identified late in the program. In some instances, major schedule slips were barely averted. In at least two cases, it was determined that a spinning upper stage was not a viable option. Historically, the "slosh" issue has been addressed by each space vehicle project individually, if it has been addressed at all. Due to budgetary and programmatic constraints, individual projects are unable to address the problem globally. Hence, there has been little effort to collect available test and flight data and use that data to make a coherent, unified picture of the "slosh" effect and how to deal with it. To some extent, each project has had to "reinvent the wheel", which can be both costly and risky. This study is a step toward correcting the situation. Specifically, the goal was to identify and collect available flight and test data for spinning vehicles with onboard liquid propellants. A total of 149 flight data points and 1,692 test points were collected as part of this study. This data was analyzed, correlated, and is presented here in a normalized form. In most cases, the normalization involves a dimensionless nutation time constant that can be used to predict performance of other vehicles with the same type of tank. For some configurations, it was also possible to identify conditions that can lead to resonance between nutational motion and liquid modes. Gaps in the knowledge base are identified and

  18. Quantum dynamics of a dipolar Fermi gas in free expansion

    NASA Astrophysics Data System (ADS)

    Nishimura, T.; Maruyama, T.

    2010-05-01

    We presented our theoretical study on quantum dynamics of a polarized dipolar Fermi gas in free expansion. The dipole-dipolar interparticle interaction induces axisymmetrical deformation of the expanding gas not only in the spatial space but also in the momentum space, so that, in order to obtain proper results in the time-of-flight method for the dipolar Fermi gas, it is necessary to deal with time-evolution of the deformation. To solve the free expansion problem, we develop the Hartree-Fock and Landau-Vlasov approaches and a new time-evolution ansatz for the quantum dynamics. In conclusion, we obtain exact predictions for the minimal quadrupole deformation of the high-temperature Maxwell-Boltzmann and zero-temperature Thomas-Fermi gases in the week-interaction and small-deformation regime, and also reveal a scaling law associated with the Liouville’s theorem in the long-time behaviors of the MB and TF gases.

  19. Validation of a Chiral Liquid Chromatographic Method for the Degradation Behavior of Flumequine Enantiomers in Mariculture Pond Water.

    PubMed

    Wang, Yan-Fei; Gao, Xiao-Feng; Jin, Huo-Xi; Wang, Yang-Guang; Wu, Wei-Jian; Ouyang, Xiao-Kun

    2016-09-01

    In this work, flumequine (FLU) enantiomers were separated using a Chiralpak OD-H column, with n-hexane-ethanol (20:80, v/v) as the mobile phase at a flow rate of 0.6 mL/min. Solid phase extraction (SPE) was used for cleanup and enrichment. The limit of detection, limit of quantitation, linearity, precision, and intra/interday variation of the chiral high-performance liquid chromatography (HPLC) method were determined. The developed method was then applied to investigate the degradation behavior of FLU enantiomers in mariculture pond water samples. The results showed that the degradation of FLU enantiomers under natural, sterile, or dark conditions was not enantioselective. Chirality 28:649-655, 2016. © 2016 Wiley Periodicals, Inc. PMID:27483447

  20. Metallic 2D Surface State of Silicon by Ionic Liquid gating and observation of Reentrant Insulating behavior

    NASA Astrophysics Data System (ADS)

    Nelson, J. J.; Goldman, A. M.

    2015-03-01

    Metal insulator transitions are usually observed in high mobility and low carrier density 2D electron systems. There are several open questions regarding the metallic state including its existence in the limit of zero temperature. The current experimental focus is on the production of higher mobility samples to push the critical carrier density to even lower values, which will increase the effects of the Coulomb interaction. Here we report an unexpected result, the observation of the onset of a metallic state at high carrier densities in silicon gated with the ionic liquid DEME-TFSI. In addition we have observed a return to the insulating state as the carrier density was further increased. This reentrant insulting behavior is an effect that was recently predicted. Supported in part by NSF/DMR-1263316. Part of this work was carried out at the Minnesota Nanocenter.

  1. Leaching behavior of copper from waste printed circuit boards with Brønsted acidic ionic liquid

    SciTech Connect

    Huang, Jinxiu; Chen, Mengjun Chen, Haiyan; Chen, Shu; Sun, Quan

    2014-02-15

    Highlights: • A Brønsted acidic ILs was used to leach Cu from WPCBs for the first time. • The particle size of WPCBs has significant influence on Cu leaching rate. • Cu leaching rate was higher than 99% under the optimum leaching conditions. • The leaching process can be modeled with shrinking core model, and the E{sub a} was 25.36 kJ/mol. - Abstract: In this work, a Brønsted acidic ionic liquid, 1-butyl-3-methyl-imidazolium hydrogen sulfate ([bmim]HSO{sub 4}), was used to leach copper from waste printed circuit boards (WPCBs, mounted with electronic components) for the first time, and the leaching behavior of copper was discussed in detail. The results showed that after the pre-treatment, the metal distributions were different with the particle size: Cu, Zn and Al increased with the increasing particle size; while Ni, Sn and Pb were in the contrary. And the particle size has significant influence on copper leaching rate. Copper leaching rate was higher than 99%, almost 100%, when 1 g WPCBs powder was leached under the optimum conditions: particle size of 0.1–0.25 mm, 25 mL 80% (v/v) ionic liquid, 10 mL 30% hydrogen peroxide, solid/liquid ratio of 1/25, 70 °C and 2 h. Copper leaching by [bmim]HSO{sub 4} can be modeled with the shrinking core model, controlled by diffusion through a solid product layer, and the kinetic apparent activation energy has been calculated to be 25.36 kJ/mol.

  2. Arteriovenous malformation in the brain: a theoretical study explaining the behavior of liquid embolic agents during endovascular treatment.

    PubMed

    Lv, Xianli; Wu, Zhongxue; Li, Youxiang

    2013-12-01

    There is no theoretical study on blood flow in brain arteriovenous malformation (AVM). We present a numerical theory on AVM and liquid embolic agent AVM embolization. Darcy's law was used to compute flow relations for brain AVMs. Maag's formula was used to explain the diffuse patterns of N-butyl-2-cyanoacrylate (NBCA) and ethylene-vinyl alcohol copolymer (EVOH) in brain AVMs. According to Darcy's law, the instantaneous blood flow rate through an AVM is directly proportional to the pressure drop between two places in the AVM and indirectly proportional to the distance between them. The greater the pressure gradient (through the AVM), the greater the discharge rate, and the discharge rate of blood will often differ through different AVM (or even through the same AVM, in a different direction) even if the same pressure gradient exists in both cases. Subsequent to Darcy's initial discovery, Maag found that the radius of NBCA or EVOH diffusion is inversely proportional to their viscosity. Darcy's Law and Maag's formula could be used to analyze flow patterns of brain AVM and liquid embolic agent behavior in AVM near ideal. PMID:24355185

  3. Wetting behavior of nonpolar nanotubes in simple dipolar liquids for varying nanotube diameter and solute-solvent interactions.

    PubMed

    Rana, Malay Kumar; Chandra, Amalendu

    2015-01-21

    Atomistic simulations of model nonpolar nanotubes in a Stockmayer liquid are carried out for varying nanotube diameter and nanotube-solvent interactions to investigate solvophobic interactions in generic dipolar solvents. We have considered model armchair type single-walled nonpolar nanotubes with increasing radii from (5,5) to (12,12). The interactions between solute and solvent molecules are modeled by the well-known Lennard-Jones and repulsive Weeks-Chandler-Andersen potentials. We have investigated the density profiles and microscopic arrangement of Stockmayer molecules, orientational profiles of their dipole vectors, time dependence of their occupation, and also the translational and rotational motion of solvent molecules in confined environments of the cylindrical nanopores and also in their external peripheral regions. The present results of structural and dynamical properties of Stockmayer molecules inside and near atomistically rough nonpolar surfaces including their wetting and dewetting behavior for varying interactions provide a more generic picture of solvophobic effects experienced by simple dipolar liquids without any specific interactions such as hydrogen bonds.

  4. Accommodative Behavior of Non-porous Molecular crystal at Solid-Gas and Solid-Liquid Interface

    NASA Astrophysics Data System (ADS)

    Mande, Hemant M.; Ghalsasi, Prasanna S.

    2015-09-01

    Molecular crystals demonstrate drastically different behavior in solid and liquid state, mainly due to their difference in structural frameworks. Therefore, designing of unique structured molecular compound which can work at both these interfaces has been a challenge. Here, we present remarkable ‘molecular’ property by non-porous molecular solid crystal, dinuclear copper complex (C6H5CH(X)NH2)2CuCl2, to reversibly ‘adsorb’ HCl gas at solid-gas interface as well as ‘accommodate’ azide anion at solid-liquid interface with crystal to crystal transformation. The latter process is driven by molecular recognition, self-assembly, and anchimeric assistance. The observed transformations are feasible due to breathing of inner and outer coordination sphere around metal center resulting in change in metal polyhedra for ‘accommodating’ guest molecule. These transformations cause changes in optical, magnetic, and/or ferroelectric property offering diversity in ‘sensing’ application. With the proposed underlying principles in these exceptional reversible and cyclic transformations, we prepared a series of compounds, can facilitate designing of novel multifunctional molecular materials.

  5. Introduction of an ionic liquid into the micropores of a metal-organic framework and its anomalous phase behavior.

    PubMed

    Fujie, Kazuyuki; Yamada, Teppei; Ikeda, Ryuichi; Kitagawa, Hiroshi

    2014-10-13

    Controlling the dynamics of ionic liquids (ILs) is a significant issue for widespread use. Metal-organic frameworks (MOFs) are ideal host materials for ILs because of their small micropores and tunable host-guest interactions. Herein, we demonstrate the first example of an IL incorporated within the micropores of a MOF. The system studied consisted of EMI-TFSA (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide) and ZIF-8 (composed of Zn(MeIM)2 ; H(MeIM)=2-methylimidazole) as the IL and MOF, respectively. Construction of the EMI-TFSA in ZIF-8 was confirmed by X-ray powder diffraction, nitrogen gas adsorption, and infrared absorption spectroscopy. Differential scanning calorimetry and solid-state NMR measurements showed that the EMI-TFSA inside the micropores demonstrated no freezing transition down to 123 K, whereas bulk EMI-TFSA froze at 231 K. Such anomalous phase behavior originates from the nanosize effect of the MOF on the IL. This result provides a novel strategy for stabilizing the liquid phase of the ILs down to a lower temperature region. PMID:25167856

  6. A study of early corrosion behaviors of FeCrAl alloys in liquid lead-bismuth eutectic environments

    NASA Astrophysics Data System (ADS)

    Lim, Jun; Nam, Hyo On; Hwang, Il Soon; Kim, Ji Hyun

    2010-12-01

    Lead and lead-bismuth eutectic (LBE) alloy have been increasingly receiving attention as heavy liquid metal coolants (HLMC) for future nuclear energy systems. The compatibility of structural materials and components with lead-bismuth eutectic liquid at high temperature is one of key issues for the commercialization of lead fast reactors. In the present study, the corrosion behaviors of iron-based alumina-forming alloys (Kanthal-AF®, PM2000, MA956) were investigated by exposing to stagnant LBE environments at 500 °C and 550 °C for up to 500 h. After exposures, the thickness and chemistry of the oxide layer on the specimens were analyzed by scanning electron microscopy, scanning transmission electron microscopy and energy dispersive X-ray spectroscopy. As a result, the oxide characteristics and the corrosion resistance were compared. In this study, it was shown that the corrosion resistance of FeCrAl ODS steels (PM2000, MA956) are superior to that of FeCrAl ferritic steel (Kanthal-AF®) in higher temperature LBE.

  7. Wetting behavior of nonpolar nanotubes in simple dipolar liquids for varying nanotube diameter and solute-solvent interactions

    SciTech Connect

    Rana, Malay Kumar; Chandra, Amalendu

    2015-01-21

    Atomistic simulations of model nonpolar nanotubes in a Stockmayer liquid are carried out for varying nanotube diameter and nanotube-solvent interactions to investigate solvophobic interactions in generic dipolar solvents. We have considered model armchair type single-walled nonpolar nanotubes with increasing radii from (5,5) to (12,12). The interactions between solute and solvent molecules are modeled by the well-known Lennard-Jones and repulsive Weeks-Chandler-Andersen potentials. We have investigated the density profiles and microscopic arrangement of Stockmayer molecules, orientational profiles of their dipole vectors, time dependence of their occupation, and also the translational and rotational motion of solvent molecules in confined environments of the cylindrical nanopores and also in their external peripheral regions. The present results of structural and dynamical properties of Stockmayer molecules inside and near atomistically rough nonpolar surfaces including their wetting and dewetting behavior for varying interactions provide a more generic picture of solvophobic effects experienced by simple dipolar liquids without any specific interactions such as hydrogen bonds.

  8. Accommodative Behavior of Non-porous Molecular crystal at Solid-Gas and Solid-Liquid Interface

    PubMed Central

    Mande, Hemant M.; Ghalsasi, Prasanna S.

    2015-01-01

    Molecular crystals demonstrate drastically different behavior in solid and liquid state, mainly due to their difference in structural frameworks. Therefore, designing of unique structured molecular compound which can work at both these interfaces has been a challenge. Here, we present remarkable ‘molecular’ property by non-porous molecular solid crystal, dinuclear copper complex (C6H5CH(X)NH2)2CuCl2, to reversibly ‘adsorb’ HCl gas at solid-gas interface as well as ‘accommodate’ azide anion at solid-liquid interface with crystal to crystal transformation. The latter process is driven by molecular recognition, self-assembly, and anchimeric assistance. The observed transformations are feasible due to breathing of inner and outer coordination sphere around metal center resulting in change in metal polyhedra for ‘accommodating’ guest molecule. These transformations cause changes in optical, magnetic, and/or ferroelectric property offering diversity in ‘sensing’ application. With the proposed underlying principles in these exceptional reversible and cyclic transformations, we prepared a series of compounds, can facilitate designing of novel multifunctional molecular materials. PMID:26411980

  9. Decay behavior of screened electrostatic surface forces in ionic liquids: the vital role of non-local electrostatics.

    PubMed

    Kjellander, Roland

    2016-07-28

    Screened electrostatic surface forces, also called double layer forces, between surfaces in ionic liquids can, depending on the circumstances, decay in an exponentially damped, oscillatory manner or in a plain exponential way (the latter as in dilute electrolyte solutions where ion-ion correlations are very weak). The occurrence of both of these behaviors in dense ionic liquids, where ion-ion correlations are very strong, is analyzed in the current work using exact statistical mechanics formulated in a manner that is physically transparent. A vital ingredient in understanding the decay behaviors is the fact that electrostatics in dense electrolytes have a non-local nature caused by the strong correlations. It is shown that the effects of non-locality can be elucidated by a remarkably simple, general expression for the decay parameter κ that replaces the classical expression for the inverse Debye length κDH of the Debye-Hückel (DH) and non-linear Poisson-Boltzmann approximations. This exact expression is valid for both the plain exponential and the oscillatory cases. It shows how strong correlations can give rise to plain exponential decay with a long decay length. Such a decay can arise from anion-cation associations of various kinds, for instance transient ion pairing or association caused by many-body correlations; ion pairing is a possibility but not a necessity for this to occur. Theoretical analysis is done for systems consisting of ions with an arbitrary shape and internal charge density and immersed planar walls with arbitrary internal charge distribution and any short-range ion-surface interaction. The screened electrostatic surface force between two walls is at large separations proportional to the product of effective surface charge densities of each wall. For the oscillatory case, each wall contributes with a phase shift to the oscillations of the interaction. PMID:27356099

  10. A simplified computer program for the prediction of the linear stability behavior of liquid propellant combustors

    NASA Technical Reports Server (NTRS)

    Mitchell, C. E.; Eckert, K.

    1979-01-01

    A program for predicting the linear stability of liquid propellant rocket engines is presented. The underlying model assumptions and analytical steps necessary for understanding the program and its input and output are also given. The rocket engine is modeled as a right circular cylinder with an injector with a concentrated combustion zone, a nozzle, finite mean flow, and an acoustic admittance, or the sensitive time lag theory. The resulting partial differential equations are combined into two governing integral equations by the use of the Green's function method. These equations are solved using a successive approximation technique for the small amplitude (linear) case. The computational method used as well as the various user options available are discussed. Finally, a flow diagram, sample input and output for a typical application and a complete program listing for program MODULE are presented.

  11. Liquid crystal behavior induced assembling fabrication of conductive chiral MWCNTs@NCC nanopaper

    NASA Astrophysics Data System (ADS)

    Ren, Yumei; Wang, Tianjiao; Chen, Zhimin; Li, Jing; Tian, Qiuge; Yang, Hongxia; Xu, Qun

    2016-11-01

    The conductive chiral MWCNTs@NCC nanopapers obtained by the assembly of nanocrystalline cellulose liquid crystals (NCC LCs) host matrix along with one-dimensional (1-D) multi-walled carbon nanotubes (MWCNTs) have been studied in this work. Circular dichroism (CD) studies show strong signals stemming from the chiral nematic structure. Notably, the introduction of the MWCNTs has a pronounced effect on the chiral structure of the as-prepared nanopaper. Our experimental results indicate the multiple weak molecular interactions existing between MWCNTs and NCC are responsible for the effective dispersion and stabilization of MWCNTs. Moreover it also confirms the resulting nanopaper has an increased conductivity of 4.2 S/m at 1.96 wt% MWCNTs. So the co-assembly of the nanocomposite herein opens a gateway for preparing functional materials combining the photonic properties of the NCC LCs matrix with other building blocks that can supply other advantageous functions.

  12. Homeotropic orientation behavior of nematic liquid crystals induced by copper ions.

    PubMed

    Li, Guang; Gao, Bin; Yang, Meng; Chen, Long-Cong; Xiong, Xing-Liang

    2015-06-01

    A homeotropic ordering film of nematic liquid crystal (LC) induced by copper ions (Cu(2+)) had been developed. The Cu(ClO4)2 was directly spin-coated on the glass substrate without any other chemical modification. A homeotropic orientation of LC thin-film was generated by the interfacial chemical interaction between nitrile-containing LC and copper ions on the surface. Results showed that an appropriate density of Cu(2+) could shorten the response time of orientation, but a shelf-time was prolonged. The LC film fabrication not only offered a simple process, but also presented a great repeatability to detect organophosphonates (DMMP). This study provided guidance for the design of LC films responding to organic molecules as a biosensor. PMID:25935262

  13. Lipid-Based Liquid Crystals As Carriers for Antimicrobial Peptides: Phase Behavior and Antimicrobial Effect.

    PubMed

    Boge, Lukas; Bysell, Helena; Ringstad, Lovisa; Wennman, David; Umerska, Anita; Cassisa, Viviane; Eriksson, Jonny; Joly-Guillou, Marie-Laure; Edwards, Katarina; Andersson, Martin

    2016-05-01

    The number of antibiotic-resistant bacteria is increasing worldwide, and the demand for novel antimicrobials is constantly growing. Antimicrobial peptides (AMPs) could be an important part of future treatment strategies of various bacterial infection diseases. However, AMPs have relatively low stability, because of proteolytic and chemical degradation. As a consequence, carrier systems protecting the AMPs are greatly needed, to achieve efficient treatments. In addition, the carrier system also must administrate the peptide in a controlled manner to match the therapeutic dose window. In this work, lyotropic liquid crystalline (LC) structures consisting of cubic glycerol monooleate/water and hexagonal glycerol monooleate/oleic acid/water have been examined as carriers for AMPs. These LC structures have the capability of solubilizing both hydrophilic and hydrophobic substances, as well as being biocompatible and biodegradable. Both bulk gels and discrete dispersed structures (i.e., cubosomes and hexosomes) have been studied. Three AMPs have been investigated with respect to phase stability of the LC structures and antimicrobial effect: AP114, DPK-060, and LL-37. Characterization of the LC structures was performed using small-angle X-ray scattering (SAXS), dynamic light scattering, ζ-potential, and cryogenic transmission electron microscopy (Cryo-TEM) and peptide loading efficacy by ultra performance liquid chromatography. The antimicrobial effect of the LCNPs was investigated in vitro using minimum inhibitory concentration (MIC) and time-kill assay. The most hydrophobic peptide (AP114) was shown to induce an increase in negative curvature of the cubic LC system. The most polar peptide (DPK-060) induced a decrease in negative curvature while LL-37 did not change the LC phase at all. The hexagonal LC phase was not affected by any of the AMPs. Moreover, cubosomes loaded with peptides AP114 and DPK-060 showed preserved antimicrobial activity, whereas particles loaded

  14. Behavior of a thermotropic nematic liquid crystal confined to controlled pore glasses as studied by 129Xe NMR spectroscopy.

    PubMed

    Tallavaara, Pekka; Telkki, Ville-Veikko; Jokisaari, Jukka

    2006-11-01

    The behavior of nematic liquid crystal (LC) Merck Phase 4 confined to controlled pore glass (CPG) materials was investigated using 129Xe nuclear magnetic resonance (NMR) spectroscopy of xenon gas dissolved in the LC. The average pore diameters of the materials varied from 81 to 2917 A, and the measurements were carried out within a wide temperature range (approximately 185-370 K). The spectra contain lots of information about the effect of confinement on the phase of the LC. The theoretical model of shielding of noble gases dissolved in liquid crystals on the basis of pairwise additivity approximation was applied to the analysis of the spectra. When pore diameter is small, smaller than approximately 150 A, xenon experiences on average an isotropic environment inside the pore, and no nematic-isotropic phase transition is observed. When the size is larger than approximately 150 A, nematic phase is observed, and the LC molecules are oriented along pore axis. The orientational order parameter of the LC, S, increases with increasing pore size. In the largest pores, the orientation of the molecules deviates from the pore axis direction to magnetic field direction, which implies that the size of the pores (approximately 3000 A) is close to magnetic coherence length. The decrease of magnetic coherence length with increasing temperature is clearly seen from the spectra. When the sample is cooled rapidly by immersing it in liquid nitrogen, xenon atoms do not squeeze out from the solid, as they do during gradual freezing, but they are occluded inside the solid lattice, and their chemical shift is very sensitive to crystal structure. This makes it possible to study the effect of confinement on the solid phases. According to the measured 129Xe NMR spectra, possibly three different solid phases are observed from bulk liquid crystal in the used temperature region. The same is also seen from the samples containing larger pores (pore size larger than approximately 500 A), and the

  15. Pauli blocking in low-dimensional Fermi systems at finite temperatures

    NASA Astrophysics Data System (ADS)

    Sevilla, Francisco J.; Fortes, M.; Solis, M. A.

    2010-03-01

    The chemical potential of an ideal Fermi gas for dimensions d<2 increases with temperature up to a maximum value [1], in sharp contrast with the monotonic decreasing behavior in the d=3 case [2]. The origin of this anomaly is examined in systems of non interacting fermions described by a more general energy-momentum dispersion relation ɛk^s. We show that the abnormal behavior is caused by the interplay of the density of states as a function of d/s and the exclusion principle producing a Pauli-blocking effect at finite temperatures. In the one-dimensional ideal Fermi gas, the effect is manifest up to temperatures as large as the Fermi temperature.[4pt] [1] M. Grether, M. de Llano, and M.A. Sol'is, Eur. Phys. J. D 25, 287 (2003).[0pt] [2] G. Cook and R.H. Dickerson, Am. J. Phys. 63 (8), 737 (1995).

  16. Coherent quasiparticles with a small fermi surface in lightly doped Sr(3)Ir(2)O(7).

    PubMed

    de la Torre, A; Hunter, E C; Subedi, A; McKeown Walker, S; Tamai, A; Kim, T K; Hoesch, M; Perry, R S; Georges, A; Baumberger, F

    2014-12-19

    We characterize the electron doping evolution of (Sr_{1-x}La_{x})_{3}Ir_{2}O_{7} by means of angle-resolved photoemission. Concomitant with the metal insulator transition around x≈0.05 we find the emergence of coherent quasiparticle states forming a closed small Fermi surface of volume 3x/2, where x is the independently measured La concentration. The quasiparticle weight Z remains large along the entire Fermi surface, consistent with the moderate renormalization of the low-energy dispersion, and no pseudogap is observed. This indicates a conventional, weakly correlated Fermi liquid state with a momentum independent residue Z≈0.5 in lightly doped Sr_{3}Ir_{2}O_{7}. PMID:25554897

  17. Coherent quasiparticles with a small fermi surface in lightly doped Sr(3)Ir(2)O(7).

    PubMed

    de la Torre, A; Hunter, E C; Subedi, A; McKeown Walker, S; Tamai, A; Kim, T K; Hoesch, M; Perry, R S; Georges, A; Baumberger, F

    2014-12-19

    We characterize the electron doping evolution of (Sr_{1-x}La_{x})_{3}Ir_{2}O_{7} by means of angle-resolved photoemission. Concomitant with the metal insulator transition around x≈0.05 we find the emergence of coherent quasiparticle states forming a closed small Fermi surface of volume 3x/2, where x is the independently measured La concentration. The quasiparticle weight Z remains large along the entire Fermi surface, consistent with the moderate renormalization of the low-energy dispersion, and no pseudogap is observed. This indicates a conventional, weakly correlated Fermi liquid state with a momentum independent residue Z≈0.5 in lightly doped Sr_{3}Ir_{2}O_{7}.

  18. Observation of Shock Waves in a Strongly Interacting Fermi Gas

    SciTech Connect

    Joseph, J. A.; Thomas, J. E.; Kulkarni, M.; Abanov, A. G.

    2011-04-15

    We study collisions between two strongly interacting atomic Fermi gas clouds. We observe exotic nonlinear hydrodynamic behavior, distinguished by the formation of a very sharp and stable density peak as the clouds collide and subsequent evolution into a boxlike shape. We model the nonlinear dynamics of these collisions by using quasi-1D hydrodynamic equations. Our simulations of the time-dependent density profiles agree very well with the data and provide clear evidence of shock wave formation in this universal quantum hydrodynamic system.

  19. Observation of shock waves in a strongly interacting Fermi gas.

    PubMed

    Joseph, J A; Thomas, J E; Kulkarni, M; Abanov, A G

    2011-04-15

    We study collisions between two strongly interacting atomic Fermi gas clouds. We observe exotic nonlinear hydrodynamic behavior, distinguished by the formation of a very sharp and stable density peak as the clouds collide and subsequent evolution into a boxlike shape. We model the nonlinear dynamics of these collisions by using quasi-1D hydrodynamic equations. Our simulations of the time-dependent density profiles agree very well with the data and provide clear evidence of shock wave formation in this universal quantum hydrodynamic system.

  20. Effects of ionic liquids on the survival, movement, and feeding behavior of the freshwater snail, Physa acuta.

    PubMed

    Bernot, Randall J; Kennedy, Erin E; Lamberti, Gary A

    2005-07-01

    Room-temperature ionic liquids (ILs) are being promoted as environmentally friendly alternatives to volatile organic solvents currently used by industry. Because ILs are novel and not yet in widespread use, their potential impact on aquatic organisms is unclear. We studied the effects of several ILs on the survivorship and behavior (movement and feeding rates) of the freshwater pulmonate snail, Physa acuta. Median lethal concentrations (LC50s) of ILs with imidazolium- and pyridinium-based cations and Br- and PF6- as anions ranged from 1 to 325 mg/L. Toxicity was greatest for ILs with eight-carbon alkyl chains attached to both imidazolium and pyridinium rings and declined with shorter alkyl chains, indicating a positive relationship between alkyl chain length and toxicity. Compared to controls, snails moved more slowly when exposed to butyl- and hexyl-cation ILs at 1 to 3% of LC50 concentrations but were not affected at higher IL concentrations (4-10% of LC50), which is characteristic of U-shaped dose-response curves. Snail movement was not affected by ILs with octyl alkyl groups. Grazing patterns, however, indicated that snails grazed less at higher IL concentrations. Physa acuta egestion rates were reduced in the presence of ILs at 3 to 10% of LC50 concentrations. Thus, nonlethal IL concentrations affected P. acuta behaviors, potentially impacting individual fitness and food web interactions. These results provide initial information needed to assess the potential hazards of ILs should they reach freshwater ecosystems.

  1. End Groups of Functionalized Siloxane Oligomers Direct Block-Copolymeric or Liquid-Crystalline Self-Assembly Behavior

    PubMed Central

    2016-01-01

    Monodisperse oligodimethylsiloxanes end-functionalized with the hydrogen-bonding ureidopyrimidinone (UPy) motif undergo phase separation between their aromatic end groups and dimethylsiloxane midblocks to form ordered nanostructures with domain spacings of <5 nm. The self-assembly behavior of these well-defined oligomers resembles that of high degree of polymerization (N)–high block interaction parameter (χ) linear diblock copolymers despite their small size. Specifically, the phase morphology varies from lamellar to hexagonal to body-centered cubic with increasing asymmetry in molecular volume fraction. Mixing molecules with different molecular weights to give dispersity >1.13 results in disorder, showing importance of molecular monodispersity for ultrasmall ordered phase separation. In contrast, oligodimethylsiloxanes end-functionalized with an O-benzylated UPy derivative self-assemble into lamellar nanostructures regardless of volume fraction because of the strong preference of the end groups to aggregate in a planar geometry. Thus, these molecules display more classically liquid-crystalline self-assembly behavior where the lamellar bilayer thickness is determined by the siloxane midblock. Here the lamellar nanostructure is tolerant to molecular polydispersity. We show the importance of end groups in high χ–low N block molecules, where block-copolymer-like self-assembly in our UPy-functionalized oligodimethylsiloxanes relies upon the dominance of phase separation effects over directional end group aggregation. PMID:27054381

  2. Phase behavior and microstructure of microemulsions with a room-temperature ionic liquid as the polar phase.

    PubMed

    Atkin, Rob; Warr, Gregory G

    2007-08-01

    Microemulsions of nonionic alkyl oligoethyleneoxide (CiEj) surfactants, alkanes, and ethylammonium nitrate (EAN), a room-temperature ionic liquid, have been prepared and characterized. Studies of phase behavior reveal that EAN microemulsions have many features in common with corresponding aqueous systems, the primary difference being that higher surfactant concentrations and longer surfactant tailgroups are required to offset the decreased solvophobicity the surfactant molecules in EAN compared with water. The response of the EAN microemulsions to variation in the length of the alkane, surfactant headgroup, and surfactant tailgroup has been found to parallel that observed in aqueous systems in most instances. EAN microemulsions exhibit a single broad small-angle X-ray scattering peak, like aqueous systems. These are well described by the Teubner-Strey model. A lamellar phase was also observed for surfactants with longer tails at lower temperatures. The scattering peaks of both microemulsion and lamellar phases move to lower wave vector on increasing temperature. This is ascribed to a decrease in the interfacial area of the surfactant layer. Phase behavior, small-angle X-ray scattering, and conductivity experiments have allowed the weakly to strongly structured transition to be identified for EAN systems. PMID:17636975

  3. Fermi Sees Antimatter-Hurling Thunderstorms

    NASA Video Gallery

    NASA's Fermi Gamma-ray Space Telescope has detected beams of antimatter launched by thunderstorms. Acting like enormous particle accelerators, the storms can emit gamma-ray flashes, called TGFs, an...

  4. Fermi Proves Supernova Remnants Make Cosmic Rays

    NASA Video Gallery

    The husks of exploded stars produce some of the fastest particles in the cosmos. New findings by NASA's Fermi show that two supernova remnants accelerate protons to near the speed of light. The pro...

  5. RF Spectroscopy on a Homogeneous Fermi Gas

    NASA Astrophysics Data System (ADS)

    Yan, Zhenjie; Mukherjee, Biswaroop; Patel, Parth; Struck, Julian; Zwierlein, Martin

    2016-05-01

    Over the last two decades RF spectroscopy has been established as an indispensable tool to probe a large variety of fundamental properties of strongly interacting Fermi gases. This ranges from measurement of the pairing gap over tan's contact to the quasi-particle weight of Fermi polarons. So far, most RF spectroscopy experiments have been performed in harmonic traps, resulting in an averaged response over different densities. We have realized an optical uniform potential for ultracold Fermi gases of 6 Li atoms, which allows us to avoid the usual problems connected to inhomogeneous systems. Here we present recent results on RF spectroscopy of these homogeneous samples with a high signal to noise ratio. In addition, we report progress on measuring the contact of a unitary Fermi gas across the normal to superfluid transition.

  6. Fermi's Conundrum: Proliferation and Closed Societies

    NASA Astrophysics Data System (ADS)

    Teller, Wendy; Westfall, Catherine

    2007-04-01

    On January 1, 1946 Emily Taft Douglas, a freshman Representative at Large for Illinois, sent a letter to Enrico Fermi. She wanted to know whether, if atomic energy was used for peaceful purposes, it might be possible to clandestinely divert some material for bombs. Douglas first learned about the bomb not quite five months before when Hiroshima was bombed. Even though she was not a scientist she identified a key problem of the nuclear age. Fermi responded with requirements to allow peaceful uses of atomic energy and still outlaw nuclear weapons. First, free interchange of information between people was required, and second, people who reported possible violations had to be protected. Fermi had lived in Mussolini's Italy and worked under the war time secrecy restrictions of the Manhattan Project. He was not optimistic that these conditions could be met. This paper discusses how Douglas came to recognize the proliferation issue and what led Fermi to his solution and his pessimism about its practicality.

  7. Fermi discovers giant bubbles in Milky Way

    NASA Video Gallery

    Using data from NASA's Fermi Gamma-ray Space Telescope, scientists have recently discovered a gigantic, mysterious structure in our galaxy. This feature looks like a pair of bubbles extending above...

  8. ORIGIN OF THE FERMI BUBBLE

    SciTech Connect

    Cheng, K.-S.; Chernyshov, D. O.; Dogiel, V. A.; Ko, C.-M.; Ip, W.-H.

    2011-04-10

    Fermi has discovered two giant gamma-ray-emitting bubbles that extend nearly 10 kpc in diameter north and south of the Galactic center. The existence of the bubbles was first evidenced in X-rays detected by ROSAT and later WMAP detected an excess of radio signals at the location of the gamma-ray bubbles. We propose that periodic star capture processes by the galactic supermassive black hole, Sgr A*, with a capture rate 3 x 10{sup -5} yr{sup -1} and energy release {approx}3 x 10{sup 52} erg per capture can produce very hot plasma {approx}10 keV with a wind velocity {approx}10{sup 8} cm s{sup -1} injected into the halo and heat up the halo gas to {approx}1 keV, which produces thermal X-rays. The periodic injection of hot plasma can produce shocks in the halo and accelerate electrons to {approx}TeV, which produce radio emission via synchrotron radiation and gamma rays via inverse Compton scattering with the relic and the galactic soft photons.

  9. Dynamic Study of Liquid Drop Impact on Supercooled Cerium Dioxide: Anti-Icing Behavior.

    PubMed

    Fu, Sin-Pui; Sahu, Rakesh P; Diaz, Estefan; Robles, Jaqueline Rojas; Chen, Chen; Rui, Xue; Klie, Robert F; Yarin, Alexander L; Abiade, Jeremiah T

    2016-06-21

    This work deals with the anti-icing behavior at subfreezing temperatures of CeO2/polyurethane nanocomposite coatings with and without a stearic acid treatment on aluminum alloy substrates. The samples ranged from superhydrophilic to superhydrophobic depending on surface morphology and surface functionalization. X-ray photoelectron spectroscopy was used to determine the surface composition. The anti-icing behavior was studied both by importing fog into a chamber with controlled atmosphere at subzero temperatures and by conducting experiments with drop impact velocities of 1.98, 2.8, 3.83, and 4.95 m/s. It was found that the ice-phobicity of the ceramic/polymer nanocomposite coating was dependent on the surface roughness and surface energy. Water drops were observed to completely rebound from the surface at subfreezing temperatures from superhydrophobic surfaces with small contact angle hysteresis regardless of the impact velocity, thus revealing the anti-icing capability of such surfaces. PMID:27166506

  10. Modulation of phase behaviors and charge carrier mobilities by linkage length in discotic liquid crystal dimers.

    PubMed

    Wang, Yi-Fei; Zhang, Chun-Xiu; Wu, Hao; Zhang, Ao; Wang, Jian-Chuang; Zhang, Shuai-Feng; Pu, Jia-Ling

    2015-01-28

    A clear structure-property relationship was revealed in a series of triphenylene-based dimers, which contained two triphenylene nuclei each bearing five β-OC4H9 substituents and are linked through a flexible O(CH2)nO polymethylene chain (n=6-12). Dimers with the linkage close to twice the length of the free side chains (n=8, 9) exhibited a single Colhp phase, while others with the linkage shorter (n=6, 7) or longer (n=10, 11, 12) showed multiphase behaviors with a transition from the Colhp phase to Colh phase; hole mobilities of Colhp phases reached 1.4×10(-2) cm2 V(-1) s(-1) in the dimer for which the linkage is exactly twice the length of the free side chains (n=8), and decreased regularly both with linkage length becoming shorter or longer. This modulation of phase behaviors and charge carrier mobilities was demonstrated to be generated by various steric perturbations introduced by linkages with different lengths, which result in different degrees of lateral fluctuations of discotic moieties in the columns. PMID:25467212

  11. Nonhydrodynamic Transport in Trapped Unitary Fermi Gases

    NASA Astrophysics Data System (ADS)

    Brewer, Jasmine; Romatschke, Paul

    2015-11-01

    Many strongly coupled fluids are known to share similar hydrodynamic transport properties. In this work we argue that this similarity could extend beyond hydrodynamics to transient dynamics through the presence of nonhydrodynamic modes. We review nonhydrodynamic modes in kinetic theory and gauge-gravity duality and discuss their signatures in trapped Fermi gases close to unitarity. Reanalyzing previously published experimental data we find hints of nonhydrodynamic modes in cold Fermi gases in two and three dimensions.

  12. A Fermi golden rule for quantum graphs

    NASA Astrophysics Data System (ADS)

    Lee, Minjae; Zworski, Maciej

    2016-09-01

    We present a Fermi golden rule giving rates of decay of states obtained by perturbing embedded eigenvalues of a quantum graph. To illustrate the procedure in a notationally simpler setting, we first describe a Fermi golden rule for boundary value problems on surfaces with constant curvature cusps. We also provide a resonance existence result which is uniform on compact sets of energies and metric graphs. The results are illustrated by numerical experiments.

  13. Nematic Liquid Crystal Alignment Behaviors between Crossed Stretched Miropolymer Filaments with Anchoring Effects

    NASA Astrophysics Data System (ADS)

    Fujikake, Hideo; Murashige, Takeshi; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro; Sato, Fumio

    2006-04-01

    We observed the molecular alignment of a liquid crystal (LC) induced by crossing two stretched micropolymer filaments between glass substrates and confirmed its light modulation property. The two microfilaments, which were extracted from a cellulose cloth by stretching it in advance, had surface molecular alignment and stabilized nematic LC alignment between the microfilaments crossed with a small angle. In the fabricated LC cell, a spatially-uniform LC planar alignment is achieved in the area of a filament interval of less than 60 μm. By polarizing microscopy observation of the isotropic-to-nematic wetting transition of the LC material between the polymer filaments, it was confirmed that the stable LC alignment area is formed by the surface anchoring of the filaments. When external voltages were applied to the obtained uniformed alignment LC area, a characteristic periodic electrooptic property was confirmed on the basis of electrically-controlled birefringence under the alignment control of the in-plane anchoring of the filaments.

  14. The behavior of a liquid drop levitated and drastically flattened by an intense sound field

    NASA Technical Reports Server (NTRS)

    Lee, C. P.; Anilkumar, A. V.; Wang, Taylor G.

    1992-01-01

    The deformation and break-up are studied of a liquid drop in levitation through the radiation pressure. Using high-speed photography ripples are observed on the central membrane of the drop, atomization of the membrane by emission of satellite drops from its unstable ripples, and shattering of the drop after upward buckling like an umbrella, or after horizontal expansion like a sheet. These effects are captured on video. The ripples are theorized to be capillary waves generated by the Faraday instability excited by the sound vibration. Atomization occurs whenever the membrane becomes so thin that the vibration is sufficiently intense. The vibration leads to a destabilizing Bernoulli correction in the static pressure. Buckling occurs when an existent equilibrium is unstable to a radial (i.e., tangential) motion of the membrane because of the Bernoulli effect. Besides, the radiation stress at the rim of the drop is a suction stress which can make equilibrium impossible, leading to the horizontal expansion and the subsequent break-up.

  15. Liquid phase adsorption behavior of inulin-type fructan onto activated charcoal.

    PubMed

    Li, Kecheng; Liu, Song; Xing, Ronge; Yu, Huahua; Qin, Yukun; Li, Pengcheng

    2015-05-20

    This study describes liquid phase adsorption characteristics of inulin-type fructan onto activated charcoal. Batch mode experiments were conducted to study the effects of pH, contact time, temperature and initial concentration of inulin. Nearly neutral solution (pH 6-8) was favorable to the adsorption and the equilibrium was attained after 40 min with the maximum adsorption Qmax 0.182 g/g (adsorbate/adsorbent) at 298 K. The experimental data analysis indicated that the adsorption process fitted well with the pseudo-second-order kinetic model (R(2) = 1) and Langmuir isotherms model (R(2) > 0.99). Thermodynamic parameters revealed that the adsorption process was spontaneous and exothermic with a physical nature. Inulin desorption could reach 95.9% using 50% ethanol solution and activated charcoal could be reused without significant losses in adsorption capacity. These results are of practical significance for the application of activated charcoal in the production and purification of inulin-type fructan.

  16. Anti-Adhesive Behaviors between Solid Hydrate and Liquid Aqueous Phase Induced by Hydrophobic Silica Nanoparticles.

    PubMed

    Min, Juwon; Baek, Seungjun; Somasundaran, P; Lee, Jae W

    2016-09-20

    This study introduces an "anti-adhesive force" at the interface of solid hydrate and liquid solution phases. The force was induced by the presence of hydrophobic silica nanoparticles or one of the common anti-agglomerants (AAs), sorbitan monolaurate (Span 20), at the interface. The anti-adhesive force, which is defined as the maximum pushing force that does not induce the formation of a capillary bridge between the cyclopentane (CP) hydrate particle and the aqueous solution, was measured using a microbalance. Both hydrophobic silica nanoparticles and Span 20 can inhibit adhesion between the CP hydrate probe and the aqueous phase because silica nanoparticles have an aggregative property at the interface, and Span 20 enables the hydrate surface to be wetted with oil. Adding water-soluble sodium dodecyl sulfate (SDS) to the nanoparticle system cannot affect the aggregative property or the distribution of silica nanoparticles at the interface and, thus, cannot change the anti-adhesive effect. However, the combined system of Span 20 and SDS dramatically reduces the interfacial tension: emulsion drops were formed at the interface without any energy input and were adsorbed on the CP hydrate surface, which can cause the growth of hydrate particles. Silica nanoparticles have a good anti-adhesive performance with a relatively smaller dosage and are less influenced by the presence of molecular surfactants; consequently, these nanoparticles may have a good potential for hydrate inhibition as AAs. PMID:27564571

  17. Retention behavior of alkyl-substituted polycyclic aromatic sulfur heterocycles in reversed-phase liquid chromatography.

    PubMed

    Wilson, Walter B; Sander, Lane C; de Alda, Miren Lopez; Lee, Milton L; Wise, Stephen A

    2016-08-26

    Retention indices for 79 alkyl-substituted polycyclic aromatic sulfur heterocycles (PASHs) were determined by using reversed-phase liquid chromatography (LC) on a monomeric and polymeric octadecylsilane (C18) stationary phase. Molecular shape parameters [length, breadth, thickness (T), and length-to-breadth ratio (L/B)] were calculated for all the compounds studied. Based on separations of isomeric methylated polycyclic aromatic hydrocarbons on polymeric C18 phases, alkyl-substituted PASHs are expected to elute based on increasing L/B ratios. However, the correlation coefficients had a wide range of values from r=0.43 to r=0.93. Several structural features besides L/B ratios were identified to play an important role in the separation mechanism of PASHs on polymeric C18 phases. First, the location of the sulfur atom in a bay-like-region results in alkylated-PASHs being more retentive than non-bay-like-region alkylated-PASHs, and they elute later than expected based on L/B value. Second, the placement of the alkyl group in the k region of the structure resulted in a later elution than predicted by L/B. Third, highly nonplanar methyl-PASHs (i.e., 1-Me and 11-MeBbN12T) elute prior to the parent PASH (BbN12T).

  18. Spin-liquid behavior and weak static magnetism in pyrochlore Pr2Ir2O7

    SciTech Connect

    Heffner, R H; Maclaughlin, D E; Nakatsuji, S; Machida, Y

    2008-01-01

    Muon spin relaxation experiments have been performed in powder samples of the pyrochlore iridate Pr{sub 2}Ir{sub 2}O{sub 7} for temperatures in the range 0.02-250 K. Two-component muon spin relaxation functions are observed up to {approx}> 150 K, indicating static magnetism with a freezing temperature T{sub f} of this value or higher. The static muon spin relaxation rate {Delta}. suggests weak-moment freezing ({approx} 10{sup -1} {micro}{sub B} at T = 0), probably due to Ir{sup 4+} spin ordering as in isostructural Y{sub 2}Ir{sub 2}O{sub 7}. The temperature dependence of {Delta} is highly unusual, decreasing smoothly by orders of magnitude but remaining nonzero for T < T{sub f}. The smoothness of {Delta}(T) suggests that Pr{sup 3+} moments do not order down to 0.025 K. The dynamic relaxation rate {Lambda} increases markedly below {approx}20 K, indicating a shift of spin fluctuation noise power to low frequencies in the spin-liquid state. At low temperatures {Lambda} is strong and temperature-independent, indicative of numerous low-lying spin excitations as is common in frustrated antiferromagnets.

  19. Patterning behavior of gravitationally modulated supercritical Marangoni flow in liquid layers.

    PubMed

    Lappa, Marcello

    2016-05-01

    The objective of the present analysis is the investigation of hybrid convection induced by the joint influence of imposed vibrations (g-jitters) of desired amplitude and frequency and surface-tension-induced forces in a nonisothermal liquid layer. This study may be regarded as the natural extension of an earlier work [V. M. Shevtsova, I. Nepomnyashchy, and J. C. Legros, Phys. Rev. E 67, 066308 (2003)10.1103/PhysRevE.67.066308], where the focus was on convection driven by interacting thermocapillarity and steady gravity. As in that work, conditions are considered for which the unperturbed (vibrationless) Marangoni flow would be characterized by the emergence and propagation of a classical hydrothermal wave, namely, a supercritical thermofluidynamic disturbance propagating continuously in the upstream direction. A number of numerical results are analyzed and discussed. Regimes of quasistationary rolls, standing waves, traveling waves, and modulated (pulsotraveling) disturbances are identified in the considered space of parameters. Most interestingly, it is observed that traveling waves can reverse their direction of propagation in some specific regions of the phase space. PMID:27300978

  20. Lanthanide Phytanates: Liquid-Crystalline Phase Behavior, Colloidal Particle Dispersions, and Potential as Medical Imaging Agents

    SciTech Connect

    Conn, Charlotte E.; Panchagnula, Venkateswarlu; Weerawardena, Asoka; Waddington, Lynne J.; Kennedy, Danielle F.; Drummond, Calum J.

    2010-08-23

    Lanthanide salts of phytanic acid, an isoprenoid-type amphiphile, have been synthesized and characterized. Elemental analysis and FTIR spectroscopy were used to confirm the formed product and showed that three phytanate anions are complexed with one lanthanide cation. The physicochemical properties of the lanthanide phytanates were investigated using DSC, XRD, SAXS, and cross-polarized optical microscopy. Several of the hydrated salts form a liquid-crystalline hexagonal columnar mesophase at room temperature, and samarium(III) phytanate forms this phase even in the absence of water. Select lanthanide phytanates were dispersed in water, and cryo-TEM images indicate that some structure has been retained in the dispersed phase. NMR relaxivity measurements were conducted on these systems. It has been shown that a particulate dispersion of gadolinium(III) phytanate displays proton relaxivity values comparable to those of a commercial contrast agent for magnetic resonance imaging and a colloidal dispersion of europium(III) phytanate exhibits the characteristics of a fluorescence imaging agent.