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Sample records for earth re123 cuprate

  1. Heat capacity of rare-earth cuprates, orthovanadates, and aluminum garnets, gallium garnets, and iron garnets

    NASA Astrophysics Data System (ADS)

    Denisova, L. T.; Kargin, Yu. F.; Denisov, V. M.

    2015-08-01

    The correlation between the heat capacities of rare-earth cuprates, orthovanadates, and garnets with ionic radius R 3+ has been analyzed. It has been shown that the values of C {/p 0} change consistently depending on the radius R 3+ within the corresponding tetrads (La-Nd, Pm-Gd, Gd-Ho, Eu-Lu).

  2. Sample and length-dependent variability of 77 and 4.2 K properties in nominally identical RE123 coated conductors

    NASA Astrophysics Data System (ADS)

    Rossi, L.; Hu, X.; Kametani, F.; Abraimov, D.; Polyanskii, A.; Jaroszynski, J.; Larbalestier, D. C.

    2016-05-01

    We present a broad study by multiple techniques of the critical current and critical current density of a small but representative set of nominally identical commercial RE123 (REBa2Cu3O7-δ , RE = rare Earth, here Y and Gd) coated conductors (CC) recently fabricated by SuperPower Inc. to the same nominal high pinning specification with BaZrO3 and RE2O3 nanoprecipitate pinning centers. With high-field low-temperature applications to magnet technology in mind, we address the nature of their tape-to-tape variations and length-wise I c inhomogeneities by measurements on a scale of about 2 cm rather than the 5 m scale normally supplied by the vendor and address the question of whether these variations have their origin in cross-sectional or in vortex pinning variations. Our principal method has been a continuous measurement transport critical current tool (YateStar) that applies about 0.5 T perpendicular and parallel to the tape at 77 K, thus allowing variations of c-axis and ab-plane properties to be clearly distinguished in the temperature and field regime where strong pinning defects are obvious. We also find such in-field measurements at 77 K to be more valuable in predicting 4.2 K, high-field properties than self-field, 77 K properties because the pinning centers controlling 77 K performance play a decisive role in introducing point defects that also add strongly to J c at 4.2 K. We find that the dominant source of I c variation is due to pinning center fluctuations that control J c, rather than to production defects that locally reduce the active cross-section. Given the 5-10 nm scale of these pinning centers, it appears that the route to greater I c homogeneity is through more stringent control of the REBCO growth conditions in these Zr-doped coated conductors.

  3. Coupling of the orthorhombic distortion to the depression of the {Tc}`s due to Zn{sup 2+} doping in the ``RE-123`` HTSC`s: A (d + s)-wave picture

    SciTech Connect

    Tang, I.M.; Thongruang, R.; Charoenthai, N.

    1999-07-10

    The depressions of the {Tc}`s of the 123 REBa{sub 2}Cu{sub 3}O{sub 7} HTSC`s due to the substitution of Zn{sup 2+} ions into the Cu(2) layer are studied. The orthorhombic distortion which occurs in the 123 ceramics is assumed to induce a modification to the spin-fluctuation (SF) mediated pairing interaction which in turn causes the order parameters of these HTSC`s to be of mixed (d + s)-wave symmetry. It is shown that part of the rapid depression of the {Tc}`s caused by Zn{sup 2+} substitution into the CuO{sup 2} is due to a reduction of the SF-mediated pairing interaction. The differences in the rates of suppression of {Tc} due to Zn{sup 2+} doping in the different RE-123 HTSC`s are shown to be due to the changes in the orthorhombicity which depend on the size of the rare earth ions.

  4. Direct cupration of fluoroform.

    PubMed

    Zanardi, Alessandro; Novikov, Maxim A; Martin, Eddy; Benet-Buchholz, Jordi; Grushin, Vladimir V

    2011-12-28

    We have found the first reaction of direct cupration of fluoroform, the most attractive CF(3) source for the introduction of the trifluoromethyl group into organic molecules. Treatment of CuX (X = Cl, Br, I) with 2 equiv of MOR (M = K, Na) in DMF or NMP produces novel alkoxycuprates that readily react with CF(3)H at room temperature and atmospheric pressure to give CuCF(3) derivatives. The CuCl and t-BuOK (1:2) combination provides best results, furnishing the CuCF(3) product within seconds in nearly quantitative yield. As demonstrated, neither CF(3)(-) nor CF(2) mediate the Cu-CF(3) bond formation, which accounts for its remarkably high selectivity. The fluoroform-derived CuCF(3) solutions can be efficiently stabilized with TREAT HF to produce CuCF(3) reagents that readily trifluoromethylate organic and inorganic electrophiles in the absence of additional ligands such as phenanthroline. A series of novel Cu(I) complexes have been structurally characterized, including K(DMF)[Cu(OBu-t)(2)] (1), Na(DMF)(2)[Cu(OBu-t)(2)] (2), [K(8)Cu(6)(OBu-t)(12)(DMF)(8)(I)](+) I(-) (3), and [Cu(4)(CF(3))(2)(C(OBu-t)(2))(2)(μ(3)-OBu-t)(2)] (7). PMID:22136628

  5. Raman scattering in cuprate superconductors

    SciTech Connect

    Devereaux, T.P.; Kampf, A.P.

    1997-07-20

    A theory for electronic Raman scattering in the cuprate superconductors is presented with a specific emphasis on the polarization dependence of the spectra which can infer the symmetry of the energy gap. Signatures of the effects of disorder on the low frequency and low temperature behavior of the Raman spectra for different symmetry channels provide detailed information about the magnitude and the phase of the energy gap. Properties of the theory for finite T will be discussed and compared to recent data concerning the doping dependence of the Raman spectra in cuprate superconductors, and remaining questions will be addressed.

  6. Earth

    NASA Technical Reports Server (NTRS)

    Carr, M. H.

    1984-01-01

    The following aspects of the planet Earth are discussed: plate tectonics, the interior of the planet, the formation of the Earth, and the evolution of the atmosphere and hydrosphere. The Earth's crust, mantle, and core are examined along with the bulk composition of the planet.

  7. Oxygen diffusion in cuprate superconductors

    SciTech Connect

    Routbort, J.L.; Rothman, S.J.

    1995-01-01

    Superconducting properties of the cuprate superconductors depend on the oxygen content of the material; the diffusion of oxygen is thus an important process in the fabrication and application of these materials. This article reviews studies of the diffusion of oxygen in La{sub 2}{sub {minus}}{sub {times}}Sr{sub {times}}CuO{sub 4}, YBa{sub 2}Cu{sub 3}O{sub 7}{sub {minus}}{delta}, YBa{sub 2}Cu{sub 4}O{sub 8}, and the Bi{sub 2}Sr{sub 2}Ca{sub n}{sub {minus}}{sub 1}Cu{sub n}O{sub 2}{sub +}{sub 4} (n = 1, and 2) superconductors, and attempt to elucidate the atomic mechanisms responsible.

  8. Chasing arcs in cuprate superconductors.

    SciTech Connect

    Norman, M. R.; Materials Science Division

    2009-01-01

    Important clues to the origin of high-temperature superconductivity in cuprate compounds lie within the normal phase of these compounds, which forms above the transition temperature T{sub c}. One unusual feature of the normal phase is the presence of a pseudogap; depending on the momentum of the charge carrier, its excitation energy is either zero or finite (1). Two reports in Science, by Pushp et al. (2) in June and by Lee et al. (3) on page 1099 of this issue, have used scanning tunneling microscopy to provide dramatic new insights into the pseudogap phase and to elucidate how the electronic excitations, both above and below T{sub c}, differ for different values of the carrier momentum.

  9. The color of polarization in cuprate superconductors

    NASA Technical Reports Server (NTRS)

    Hoff, H. A.; Osofsky, M. S.; Lechter, W. L.; Pande, C. S.

    1991-01-01

    A technique for the identification of individual anisotropic grains in a heterogeneous and opaque material involves the observation of grain color in reflected light through crossed polarizers (color of polarization). Such colors are generally characteristic of particular phases. When grains of many members of the class of hole carrier cuprate superconductors are so viewed at room temperature with a 'daylight' source, a characteristic color of polarization is observed. This color was studied in many of these cuprate superconductors and a strong correlation was found between color and the existence of superconductivity. Two members were also examined of the electron cuprate superconductors and it was found that they possess the same color of polarization as the hole carrier cuprate superconductors so far examined. The commonality of the characteristic color regardless of charge carrier indicates that the presence of this color is independent of carrier type. The correlation of this color with the existence of superconductivity in the cuprate superconductors suggests that the origin of the color relates to the origin of superconductivity. Photometric techniques are also discussed.

  10. Lattice, spin, and charge excitations in cuprates

    NASA Astrophysics Data System (ADS)

    Lee, Wei-Sheng

    2014-03-01

    Tracking doping evolution of elementary excitations is a crucial approach to understand the complex phenomena exhibited in cuprates. In the first part of my talk, I will discuss the role of the lattice in the quasi-one-dimensional edge-sharing cuprate Y2+xCa2-xCu5O10. Using O K-edge RIXS, we resolve site-dependent harmonic phonon excitations of a 70 meV mode. Coupled with theory, this provides a direct measurement of electron-lattice coupling strength. We show that such electron-lattice coupling causes doping-dependent distortions of the Cu-O-Cu bond angle, which sets the intra-chain spin exchange interactions. In the second part of my talk, I will discuss collective excitations in the electron-doped superconducting cuprate, Nd2-xCexCuO4 observed using Cu L-edge RIXS. Surprisingly, despite the fact that the spin stiffness is zero and the AFM correlations are short-ranged, magnetic excitations harden significantly across the AFM-HTSC phase boundary, in stark contrast with the hole-doped cuprates. Furthermore, we found an unexpected and highly dispersive mode emanating from the zone center in superconducting NCCO that is undetected in the hole-doped compounds. This may signal a quantum phase distinct from superconductivity. Thus, our results indicate an asymmetry of the collective excitations in electron- and hole-doped cuprates, providing a new perspective on the doping evolution of the cuprate ground state. This work is supported by DOE Office of Basic Energy Sciences, Materials Sciences and Engineering Division, under Contract DE-AC02-76SF00515.

  11. Enhancing critical current density of cuprate superconductors

    DOEpatents

    Chaudhari, Praveen

    2015-06-16

    The present invention concerns the enhancement of critical current densities in cuprate superconductors. Such enhancement of critical current densities include using wave function symmetry and restricting movement of Abrikosov (A) vortices, Josephson (J) vortices, or Abrikosov-Josephson (A-J) vortices by using the half integer vortices associated with d-wave symmetry present in the grain boundary.

  12. Excess Oxygen Defects in Layered Cuprates

    DOE R&D Accomplishments Database

    Lightfoot, P.; Pei, S. Y.; Jorgensen, J. D.; Manthiram, A.; Tang, X. X.; Goodenough, J. B.

    1990-09-01

    Neutron powder diffraction has been used to study the oxygen defect chemistry of two non-superconducting layered cuprates, La{sub 1. 25}Dy{sub 0.75}Cu{sub 3.75}F{sub 0.5}, having a T{sup {asterisk}}- related structure, and La{sub 1.85}Sr{sub 1.15}Cu{sub 2}O{sub 6.25}, having a structure related to that of the newly discovered double-layer superconductor La{sub 2-x}Sr{sub x}CaCu{sub 2}O{sub 6}. The role played by oxygen defects in determining the superconducting properties of layered cuprates is discussed.

  13. Impurity induced resistivity upturns in underdoped cuprates

    NASA Astrophysics Data System (ADS)

    Das, Nabyendu; Singh, Navinder

    2016-01-01

    Impurity induced low temperature upturns in both the ab-plane and the c-axis dc-resistivities of cuprates in the pseudogap state have been observed in experiments. We provide an explanation of this phenomenon by incorporating impurity scattering of the charge carriers within a phenomenological model proposed by Yang, Rice and Zhang. The scattering between charge carriers and the impurity atom is considered within the lowest order Born approximation. Resistivity is calculated within Kubo formula using the impurity renormalized spectral functions. Using physical parameters for cuprates, we describe qualitative features of the upturn phenomena and its doping evolution that coincides with the experimental findings. We stress that this effect is largely due to the strong electronic correlations.

  14. Hole-doped cuprate high temperature superconductors

    NASA Astrophysics Data System (ADS)

    Chu, C. W.; Deng, L. Z.; Lv, B.

    2015-07-01

    Hole-doped cuprate high temperature superconductors have ushered in the modern era of high temperature superconductivity (HTS) and have continued to be at center stage in the field. Extensive studies have been made, many compounds discovered, voluminous data compiled, numerous models proposed, many review articles written, and various prototype devices made and tested with better performance than their nonsuperconducting counterparts. The field is indeed vast. We have therefore decided to focus on the major cuprate materials systems that have laid the foundation of HTS science and technology and present several simple scaling laws that show the systematic and universal simplicity amid the complexity of these material systems, while referring readers interested in the HTS physics and devices to the review articles. Developments in the field are mostly presented in chronological order, sometimes with anecdotes, in an attempt to share some of the moments of excitement and despair in the history of HTS with readers, especially the younger ones.

  15. Sequential imposed layer epitaxy of cuprate films

    SciTech Connect

    Laguees, M.; Tebbji, H.; Mairet, V.; Hatterer, C.; Beuran, C.F.; Hass, N.; Xu, X.Z. ); Cavellin, C.D. )

    1994-02-01

    Layer-by-layer epitaxy has been used to grow cuprate films since the discovery of high-Tc compounds. This deposition technique is in principle suitable for the growth of layered crystalline structures. However, the sequential deposition of atomic layer by atomic layer of cuprate compounds has presently not been optimized. Nevertheless, this deposition process is the only one which allows one to build artificial cell structures such as Bi[sub 2]Sr[sub 2]Ca[sub (n[minus]1)]Cu[sub n]O[sub y] with n as large as 10. This process will also be the best one to grow films of the so-called infinite layer phase compounds belonging to the Sr[sub 1[minus]x]Ca[sub x]CuO[sub 2] family, in order to improve the transport properties and the morphological properties of the cuprate films. When performed at high substrate temperature (typically more than 600[degree]C), the layer-by-layer epitaxy of cuprates exhibits usually 3D aggregate nucleation. Then the growth of the film no longer obeys the layer-by-layer sequence imposed during the deposition. We present here two experimental situations of true 2D sequential imposed layer epitaxy; the growth at 500[degree]C under atomic oxygen pressure of Bi[sub 2]Sr[sub 2]CuO[sub 6] and of Sr[sub 1[minus]x]Ca[sub y]CuO[sub 2] phases. 20 refs., 2 figs.

  16. Quasiparticle tunneling spectroscopy of high {Tc} cuprates

    SciTech Connect

    Zasadzinski, J.; Ozyuzer, L.; Yusof, Z.; Chen, J.; Gray, K.E.; Mogilevsky, R.; Hinks, D.G.; Cobb, J.L.; Markert, J.T.

    1996-04-01

    Superconductor-insulator-normal metal (SIN) and superconductor-insulator-superconductor (SIS) tunnel junctions provide important information on pairing state symmetry and mechanism. Measurements of such junctions on high {Tc} superconductors (HTS) are reported using mechanical point contacts, which generally display the optimum characteristics that can be obtained from HTS native-surface tunnel barriers. New tunneling data on the infinite-layer cuprate, Sr{sub 1{minus}x}Nd{sub x}CuO{sub 2} are reported which show a remarkable similarity to another electron-doped cuprate, Nd{sub 1.85}Ce{sub 0.85}CuO{sub 4}. In particular, there is a strong, asymmetric linear background conductance that is indicative of inelastic tunneling from a continuum of states. A discussion is given of the anomalous dip feature found in the tunneling and photoemission data on BSCCO 2212. It is shown that a similar feature is found in many cuprate junctions and that this dip scales with the gap energy over a wide range. New data on the single-layer, tetragonal cuprate, Tl{sub 2}Ba{sub 2}CuO{sub 6} (Tl2201) are presented and discussed in light of recent published results on the similar compound HgBa{sub 2}CuO{sub 4} (Hg1201). The HG1201 data display a low, flat sub-gap tunneling conductance which is consistent with a BCS density of states whereas the T12201 data display a cusp-like feature at zero bias which is more consistent with d{sub x}2-{sub y}2 symmetry.

  17. Ferroelectricity in underdoped La-based cuprates.

    PubMed

    Viskadourakis, Z; Sunku, S S; Mukherjee, S; Andersen, B M; Ito, T; Sasagawa, T; Panagopoulos, C

    2015-01-01

    Doping a "parent" antiferromagnetic Mott insulator in cuprates leads to short-range electronic correlations and eventually to high-Tc superconductivity. However, the nature of charge correlations in the lightly doped cuprates remains unclear. Understanding the intermediate electronic phase in the phase diagram (between the parent insulator and the high-Tc superconductor) is expected to elucidate the complexity both inside and outside the superconducting dome, and in particular in the underdoped region. One such phase is ferroelectricity whose origin and relation to the properties of high-Tc superconductors is subject of current research. Here we demonstrate that ferroelectricity and the associated magnetoelectric coupling are in fact common in La-214 cuprates namely, La2-xSrxCuO4, La2LixCu1-xO4 and La2CuO4+x. It is proposed that ferroelectricity may result from local CuO6 octahedral distortions, associated with the dopant atoms and clustering of the doped charge carriers, which break spatial inversion symmetry at the local scale whereas magnetoelectric coupling can be tuned through Dzyaloshinskii-Moriya interaction. PMID:26486276

  18. Symmetry of charge order in cuprates

    NASA Astrophysics Data System (ADS)

    Comin, R.; Sutarto, R.; He, F.; da Silva Neto, E. H.; Chauviere, L.; Fraño, A.; Liang, R.; Hardy, W. N.; Bonn, D. A.; Yoshida, Y.; Eisaki, H.; Achkar, A. J.; Hawthorn, D. G.; Keimer, B.; Sawatzky, G. A.; Damascelli, A.

    2015-08-01

    Charge-ordered ground states permeate the phenomenology of 3d-based transition metal oxides, and more generally represent a distinctive hallmark of strongly correlated states of matter. The recent discovery of charge order in various cuprate families has fuelled new interest into the role played by this incipient broken symmetry within the complex phase diagram of high-Tc superconductors. Here, we use resonant X-ray scattering to resolve the main characteristics of the charge-modulated state in two cuprate families: Bi2Sr2-xLaxCuO6+δ (Bi2201) and YBa2Cu3O6+y (YBCO). We detect no signatures of spatial modulations along the nodal direction in Bi2201, thus clarifying the inter-unit-cell momentum structure of charge order. We also resolve the intra-unit-cell symmetry of the charge-ordered state, which is revealed to be best represented by a bond order with modulated charges on the O-2p orbitals and a prominent d-wave character. These results provide insights into the origin and microscopic description of charge order in cuprates, and its interplay with superconductivity.

  19. Ferroelectricity in underdoped La-based cuprates

    PubMed Central

    Viskadourakis, Z.; Sunku, S. S.; Mukherjee, S.; Andersen, B. M.; Ito, T.; Sasagawa, T.; Panagopoulos, C.

    2015-01-01

    Doping a “parent” antiferromagnetic Mott insulator in cuprates leads to short-range electronic correlations and eventually to high-Tc superconductivity. However, the nature of charge correlations in the lightly doped cuprates remains unclear. Understanding the intermediate electronic phase in the phase diagram (between the parent insulator and the high-Tc superconductor) is expected to elucidate the complexity both inside and outside the superconducting dome, and in particular in the underdoped region. One such phase is ferroelectricity whose origin and relation to the properties of high-Tc superconductors is subject of current research. Here we demonstrate that ferroelectricity and the associated magnetoelectric coupling are in fact common in La-214 cuprates namely, La2-xSrxCuO4, La2LixCu1-xO4 and La2CuO4+x. It is proposed that ferroelectricity may result from local CuO6 octahedral distortions, associated with the dopant atoms and clustering of the doped charge carriers, which break spatial inversion symmetry at the local scale whereas magnetoelectric coupling can be tuned through Dzyaloshinskii-Moriya interaction. PMID:26486276

  20. Symmetry of charge order in cuprates.

    PubMed

    Comin, R; Sutarto, R; He, F; da Silva Neto, E H; Chauviere, L; Fraño, A; Liang, R; Hardy, W N; Bonn, D A; Yoshida, Y; Eisaki, H; Achkar, A J; Hawthorn, D G; Keimer, B; Sawatzky, G A; Damascelli, A

    2015-08-01

    Charge-ordered ground states permeate the phenomenology of 3d-based transition metal oxides, and more generally represent a distinctive hallmark of strongly correlated states of matter. The recent discovery of charge order in various cuprate families has fuelled new interest into the role played by this incipient broken symmetry within the complex phase diagram of high-T(c) superconductors. Here, we use resonant X-ray scattering to resolve the main characteristics of the charge-modulated state in two cuprate families: Bi2Sr(2-x)La(x)CuO(6+δ) (Bi2201) and YBa2Cu3O(6+y) (YBCO). We detect no signatures of spatial modulations along the nodal direction in Bi2201, thus clarifying the inter-unit-cell momentum structure of charge order. We also resolve the intra-unit-cell symmetry of the charge-ordered state, which is revealed to be best represented by a bond order with modulated charges on the O-2p orbitals and a prominent d-wave character. These results provide insights into the origin and microscopic description of charge order in cuprates, and its interplay with superconductivity. PMID:26006005

  1. Enhanced pinning in mixed rare earth-123 films

    SciTech Connect

    Driscoll, Judith L.; Foltyn, Stephen R.

    2009-06-16

    An superconductive article and method of forming such an article is disclosed, the article including a substrate and a layer of a rare earth barium cuprate film upon the substrate, the rare earth barium cuprate film including two or more rare earth metals capable of yielding a superconductive composition where ion size variance between the two or more rare earth metals is characterized as greater than zero and less than about 10.times.10.sup.-4, and the rare earth barium cuprate film including two or more rare earth metals is further characterized as having an enhanced critical current density in comparison to a standard YBa.sub.2Cu.sub.3O.sub.y composition under identical testing conditions.

  2. Sr2IrO4: Gateway to cuprate superconductivity?

    DOE PAGESBeta

    Mitchell, J. F.

    2015-06-05

    High temperature superconductivity in cuprates remains a defining challenge in condensed matter physics. Recently, a new set of related compounds based on Ir rather than Cu has been discovered that may be on the verge of superconductivity themselves or be able to shed new light on the underlying interactions responsible for superconductivity in the cuprates.

  3. μSR Studies of Cuprate Superconductors

    NASA Astrophysics Data System (ADS)

    Sonier, Jeff E.

    2016-09-01

    A partial review of magnetic and superconducting properties of hole-doped cuprates determined by μSR is given. Much was learned about these materials from μSR experiments performed in the early years following the discovery of high-temperature superconductivity over an intermediate range of hole doping. Through the years improvements in sample quality and μSR instrumentation has led to new information and a refined understanding of the superconductivity and magnetism. Implicit in the discussion is the evolution of the superconducting and magnetic order parameters as a function of doping concentration, temperature and magnetic field, as evidenced by μSR.

  4. Chasing the cuprates with dilatonic dyons

    NASA Astrophysics Data System (ADS)

    Amoretti, Andrea; Baggioli, Matteo; Magnoli, Nicodemo; Musso, Daniele

    2016-06-01

    Magnetic field and momentum dissipation are key ingredients in describing condensed matter systems. We include them in gauge/gravity and systematically explore the bottom-up panorama of holographic IR effective field theories based on bulk EinsteinMaxwell Lagrangians plus scalars. The class of solutions here examined appears insufficient to capture the phenomenology of charge transport in the cuprates. We analyze in particular the temperature scaling of the resistivity and of the Hall angle. Keeping an open attitude, we illustrate weak and strong points of the approach.

  5. Unparticles and anomalous dimensions in the cuprates

    NASA Astrophysics Data System (ADS)

    Karch, Andreas; Limtragool, Kridsanaphong; Phillips, Philip W.

    2016-03-01

    Motivated by the overwhelming evidence some type of quantum criticality underlies the power-law for the optical conductivity and T-linear resistivity in the cuprates, we demonstrate here how a scale-invariant or unparticle sector can lead to a unifying description of the observed scaling forms. We adopt the continuous mass formalism or multi band (flavor) formalism of the unparticle sector by letting various microscopic parameters be mass-dependent. In particular, we show that an effective mass that varies with the flavor index as well as a running band edge and lifetime capture the AC and DC transport phenomenology of the cuprates. A key consequence of the running mass is that the effective dynamical exponent can differ from the underlying bare critical exponent, thereby providing a mechanism for realizing the fractional values of the dynamical exponent required in a previous analysis [1]. We also predict that regardless of the bare dynamical exponent, z, a non-zero anomalous dimension for the current is required. Physically, the anomalous dimension arises because the charge depends on the flavor, mass or energy. The equivalent phenomenon in a d + 1 gravitational construction is the running of the charge along the radial direction. The nature of the superconducting instability in the presence of scale invariant stuff shows that the transition temperature is not necessarily a monotonic function of the pairing interaction.

  6. Universality in Cuprates: A Gauge Approach

    NASA Astrophysics Data System (ADS)

    Marchetti, P. A.; Bighin, G.

    2016-05-01

    In high-T_c cuprates, many quantities exhibit a non-Fermi liquid universality hinting at a very peculiar structure of the underlying pairing mechanism for superconductivity: in this work, we focus on the universality for the in-plane resistivity and the superfluid density. We outline the previously developed spin-charge gauge approach to superconductivity in hole-doped cuprates: we decompose the hole of the t-t'-J model for the CuO_2 planes as the product of a spinful, chargeless gapped spinon and a spinless, charged holon with Fermi surface. Each one of these particle excitations is bound to a statistical gauge flux, allowing one to optimize their statistics. We show that this model allows for a natural interpretation of the universality: within this approach, under suitable conditions, the spinonic and holonic contributions to a response function sum up according to the Ioffe-Larkin rule. We argue that, if the spinonic contribution dominates, then one should expect strongly non-Fermi-liquid-like universality, due to the insensitivity of spinons to Fermi surface details. The in-plane resistivity and superfluid density are indeed dominated by spinons in the underdoped region. We theoretically derive these quantities, discussing their universal behaviours and comparing them with experimental data.

  7. Theory of nonequilibrium superconductivity in cuprates

    NASA Astrophysics Data System (ADS)

    Oka, Takashi; Pietilä, Ville

    2013-03-01

    Recently, nonequilibrium properties of Hi Tc superconductors are attracting much interest. This is because new experimental methods such as time resolved ARPES has been applied to cuprates and succeeded in observing the dynamics of photo-excited quasiparticles as well as the temporal evolution of the d-wave superconducting order parameter (e.g.,). One can also realize nonequilibrium states in interfaces between cuprates and metal electrodes and control the superconducting order by changing the applied bias. In order to study the dynamics of superconductivity in strongly correlated systems, we developed a novel numerical method by combining the quantum kinetic equation with the fluctuation exchange approximation (FLEX, self-consistent T-matrix approximation). This method enables us to study the interplay between pair mediating fluctuations, e.g., antiferromagnetic and charge fluctuations, and the dynamics of quasiparticles and superconducting order parameter. In the presentation, we explain the physical insights we obtain by applying this method to nonequilibrium dynamics in d-wave superconductors.

  8. Superconductivity and planar hole densities in the cuprates from NMR

    NASA Astrophysics Data System (ADS)

    Haase, Juergen; Jurkutat, Michael; Rybicki, Damian

    We show how nuclear magnetic resonance (NMR) of 63Cu and 17O provides a quantitative measure of the charge distribution in the ubiquitous CuO2 plane, the common structural feature of cuprate physics. The various materials are found to differ significantly in the local charge distribution, while the total charge per CuO2 matches expectation from stoichiometry. Using the local charges on Cu and O measured by NMR, a new three-dimensional cuprate phase diagram is drawn that consistently encompasses all cuprate materials. These appear ordered according to their maximum Tc. It is the sharing of the inherent Cu hole with O that sets an upper limit for Tc, and it correlates with the superfluid density measured by μSR, over all cuprate families.

  9. Charge-transfer gap and superexchange interaction in insulating cuprates

    SciTech Connect

    Ohta, Y.; Tohyama, T.; Maekawa, S. )

    1991-03-04

    A cluster-model analysis is made on the material dependence of the optical charge-transfer gap and antiferromagnetic superexchange interaction of a variety of insulating cuprates. It is shown that the electronic structure of cuprates typically of the charge-transfer type is characterized by the unique energy-level separation that reflects the three dimensionality of the crystal via the long-range Madelung potential; such characteristics are absent in the Mott-Hubbard regime.

  10. Two band model for the cuprates

    NASA Astrophysics Data System (ADS)

    Liu, Shiu; White, Steven

    2009-03-01

    We use a numerical canonical transformation approach to derive an effective two-band model for the hole-doped cuprates, which keeps both oxygen and copper orbitals but removes double occupancy from each. A similar model was considered previously by Frenkel, Gooding, Shraiman, and Siggia (PRB 41, number 1, page 350). We compare the numerically derived model with previously obtained analytical results. In addition to the usual hopping terms between oxygens tpp and Cu-Cu exchange terms Jdd, the model also includes a strong copper-oxygen exchange interaction Jpd and a Kondo-like spin-flip oxygen-oxygen hopping term Kpdp. We use the density matrix renormalization group to study the charge, spin, and pairing properties of the derived model on ladder systems.

  11. Fermi surface anisotropy in the cuprates

    NASA Astrophysics Data System (ADS)

    Ramshaw, Brad

    Broken rotational (C4) symmetry is a distinguishing feature for a number of experiments in the underdoped high-Tc cuprates, including electrical resistivity, neutron scattering, Nernst coefficient, and scanning tunneling microscopy. This broken symmetry has not been observed on the Fermi surface, however, with or without the presence of an applied magnetic field. We measure the angle-dependent magnetoresistance-a quantity known to be extremely sensitive to the geometry and symmetry of the Fermi surface-of YBa2Cu3O6.58, and find that the Fermi surface has a clear two-fold symmetry, breaking the C4 symmetry of the copper-oxide plane. We discuss the implications of this finding, including how it fits with recent X-ray measurements in high magnetic fields.

  12. Antiferromagnetically Induced Photoemission Band in the Cuprates

    NASA Astrophysics Data System (ADS)

    Haas, Stephan; Moreo, Adriana; Dagotto, Elbio

    1995-05-01

    Strong antiferromagnetic correlations in models of high critical temperature (high- Tc) cuprates produce quasiparticlelike features in photoemission (PES) calculations above the Fermi momentum pF corresponding to weakly interacting electrons. This effect, discussed before by Kampf and Schrieffer [Phys. Rev. B 41, 6399 (1990)], is analyzed here using computational techniques in strong coupling. It is concluded that weight above pF should be observable in PES data for underdoped compounds, while in the overdoped regime it will be hidden in the experimental background. At optimal doping the signal is weak. The order of magnitude of our results is compatible with experimental data by Aebi et al. [Phys. Rev. Lett. 72, 2757 (1994)] for Bi2Sr2CaCu2O8.

  13. Pairing, pseudogap and Fermi arcs in cuprates

    SciTech Connect

    Kaminski, Adam; Kondo, Takeshi; Takeuchi, Tsunehiro; Gu, Genda

    2014-04-29

    We use Angle Resolved Photoemission Spectroscopy (ARPES) to study the relationship between the pseudogap, pairing and Fermi arcs in cuprates. High quality data measured over a wide range of dopings reveals a consistent picture of Fermiology and pairing in these materials. The pseudogap is due to an ordered state that competes with superconductivity rather than preformed pairs. Pairing does occur below Tpair ~ 150K and significantly above Tc, but well below T* and the doping dependence of this temperature scale is distinct from that of the pseudogap. The d-wave gap is present below Tpair, and its interplay with strong scattering creates “artificial” Fermi arcs for Tc ≤ T ≤ Tpair. However, above Tpair, the pseudogap exists only at the antipodal region. This leads to presence of real, gapless Fermi arcs close to the node. The length of these arcs remains constant up to T*, where the full Fermi surface is recovered. As a result, we demonstrate that these findings resolve a number of seemingly contradictory scenarios.

  14. Pairing, pseudogap and Fermi arcs in cuprates

    DOE PAGESBeta

    Kaminski, Adam; Kondo, Takeshi; Takeuchi, Tsunehiro; Gu, Genda

    2014-04-29

    We use Angle Resolved Photoemission Spectroscopy (ARPES) to study the relationship between the pseudogap, pairing and Fermi arcs in cuprates. High quality data measured over a wide range of dopings reveals a consistent picture of Fermiology and pairing in these materials. The pseudogap is due to an ordered state that competes with superconductivity rather than preformed pairs. Pairing does occur below Tpair ~ 150K and significantly above Tc, but well below T* and the doping dependence of this temperature scale is distinct from that of the pseudogap. The d-wave gap is present below Tpair, and its interplay with strong scatteringmore » creates “artificial” Fermi arcs for Tc ≤ T ≤ Tpair. However, above Tpair, the pseudogap exists only at the antipodal region. This leads to presence of real, gapless Fermi arcs close to the node. The length of these arcs remains constant up to T*, where the full Fermi surface is recovered. As a result, we demonstrate that these findings resolve a number of seemingly contradictory scenarios.« less

  15. Fermi-surface reconstruction by stripe order in cuprate superconductors

    PubMed Central

    Laliberté, F.; Chang, J.; Doiron-Leyraud, N.; Hassinger, E.; Daou, R.; Rondeau, M.; Ramshaw, B.J.; Liang, R.; Bonn, D.A.; Hardy, W.N.; Pyon, S.; Takayama, T.; Takagi, H.; Sheikin, I.; Malone, L.; Proust, C.; Behnia, K.; Taillefer, Louis

    2011-01-01

    The origin of pairing in a superconductor resides in the underlying normal state. In the cuprate high-temperature superconductor YBa2Cu3Oy (YBCO), application of a magnetic field to suppress superconductivity reveals a ground state that appears to break the translational symmetry of the lattice, pointing to some density-wave order. Here we use a comparative study of thermoelectric transport in the cuprates YBCO and La1.8−xEu0.2SrxCuO4 (Eu-LSCO) to show that the two materials exhibit the same process of Fermi-surface reconstruction as a function of temperature and doping. The fact that in Eu-LSCO this reconstruction coexists with spin and charge modulations that break translational symmetry shows that stripe order is the generic non-superconducting ground state of hole-doped cuprates. PMID:21847106

  16. Global Phase Diagram of the High-Tc Cuprates

    NASA Astrophysics Data System (ADS)

    Chen, Han-Dong; Zhang, Shou-Cheng

    2006-02-01

    We propose a bosonic effective quantum Hamiltonian based on the projected SO(5) model with extended interactions, which can be derived from the microscopic models of the cuprates. The global phase diagram of this model is obtained using mean-field theory and the quantum Monte Carlo simulation. We show that this single quantum model can account for most salient features observed in the high-Tc cuprates, with different families of the cuprates attributed to different traces in the global phase diagram. A particular prediction of this theory is the checkerboard state of the d-wave hole pairs formed at certain magic filling fractions. We shall describe various properties of this state and present evidence that this novel state has been detected in recent STM and transport experiments.

  17. Fermi-surface reconstruction by stripe order in cuprate superconductors.

    PubMed

    Laliberté, F; Chang, J; Doiron-Leyraud, N; Hassinger, E; Daou, R; Rondeau, M; Ramshaw, B J; Liang, R; Bonn, D A; Hardy, W N; Pyon, S; Takayama, T; Takagi, H; Sheikin, I; Malone, L; Proust, C; Behnia, K; Taillefer, Louis

    2011-01-01

    The origin of pairing in a superconductor resides in the underlying normal state. In the cuprate high-temperature superconductor YBa(2)Cu(3)O(y) (YBCO), application of a magnetic field to suppress superconductivity reveals a ground state that appears to break the translational symmetry of the lattice, pointing to some density-wave order. Here we use a comparative study of thermoelectric transport in the cuprates YBCO and La(1.8-x)Eu(0.2)Sr(x)CuO(4) (Eu-LSCO) to show that the two materials exhibit the same process of Fermi-surface reconstruction as a function of temperature and doping. The fact that in Eu-LSCO this reconstruction coexists with spin and charge modulations that break translational symmetry shows that stripe order is the generic non-superconducting ground state of hole-doped cuprates. PMID:21847106

  18. Crucial Role of Internal Collective Modes in Underdoped Cuprates

    NASA Astrophysics Data System (ADS)

    Mallik, Aabhaas V.; Yadav, Umesh K.; Medhi, Amal; Krishnamurthy, H. R.; Shenoy, Vijay B.

    The enigmatic cuprate superconductors have attracted resurgent interest with several recent reports and discussions of competing orders in the underdoped side. Motivated by this, here we address the natural question of frailty of the d-wave superconducting state in underdoped cuprates. Using a combination of theoretical approaches we study a t - J like model. We report an - as yet unexplored - instability that is brought about by an ``internal'' fluctuation (anti-symmetric mode) of the d-wave state. This new theoretical result helps in understanding recent ARPES and STM studies. We also suggest further experiments to uncover this physics. Work supported by CSIR, UGC, DST and DAE.

  19. Non-separable pairing interaction kernels applied to superconducting cuprates

    NASA Astrophysics Data System (ADS)

    Haley, Stephen B.; Fink, Herman J.

    2014-05-01

    A pairing Hamiltonian H(Γ) with a non-separable interaction kernel Γ produces HTS for relatively weak interactions. The doping and temperature dependence of Γ(x,T) and the chemical potential μ(x) is determined by a probabilistic filling of the electronic states in the cuprate unit cell. A diverse set of HTS and normal state properties is examined, including the SC phase transition boundary TC(x), SC gap Δ(x,T), entropy S(x,T), specific heat C(x,T), and spin susceptibility χs(x,T). Detailed x,T agreement with cuprate experiment is obtained for all properties.

  20. Exploring intertwined orders in cuprate superconductors

    DOE PAGESBeta

    Tranquada, John M.

    2014-11-22

    In this study, the concept of intertwined orders has been introduced to describe the cooperative relationship between antiferromagnetic spin correlations and electron (or hole) pair correlations that develop in copper-oxide superconductors. This contrasts with systems in which, for example, charge-density-wave (CDW) order competes for Fermi surface area with superconductivity. La2-xBaxCuO4 with x = 0.125 provides an example in which the ordering of spin stripes coincides with the onset of two-dimensional superconducting correlations. The apparent frustration of the interlayer Josephson coupling has motivated the concept of the pair-density-wave superconductor, a state that theoretical calculations show to be energetically competitive with themore » uniform d-wave superconductor. Even at x = 0.095, where there is robust superconductivity below 32 K in zero field, the coexistence of strong, low-energy, incommensurate spin excitations implies a spatially modulated and intertwined pair wave function. Recent observations of CDW order in YBa2Cu3O6+x and other cuprate families have raised interesting questions regarding the general role of charge modulations and the relation to superconductivity. While there are differences in the doping dependence of the modulation wave vectors in YBa2Cu3O6+x and La2-xBaxCuO4, the maximum ordering strength is peaked at the hole concentration of 1/8 in both cases. There are also possible connections with the quantum oscillations that have been detected about the same hole concentration but at high magnetic fields. Resolving these relationships remains a research challenge.« less

  1. Exploring intertwined orders in cuprate superconductors

    SciTech Connect

    Tranquada, John M.

    2014-11-22

    In this study, the concept of intertwined orders has been introduced to describe the cooperative relationship between antiferromagnetic spin correlations and electron (or hole) pair correlations that develop in copper-oxide superconductors. This contrasts with systems in which, for example, charge-density-wave (CDW) order competes for Fermi surface area with superconductivity. La2-xBaxCuO4 with x = 0.125 provides an example in which the ordering of spin stripes coincides with the onset of two-dimensional superconducting correlations. The apparent frustration of the interlayer Josephson coupling has motivated the concept of the pair-density-wave superconductor, a state that theoretical calculations show to be energetically competitive with the uniform d-wave superconductor. Even at x = 0.095, where there is robust superconductivity below 32 K in zero field, the coexistence of strong, low-energy, incommensurate spin excitations implies a spatially modulated and intertwined pair wave function. Recent observations of CDW order in YBa2Cu3O6+x and other cuprate families have raised interesting questions regarding the general role of charge modulations and the relation to superconductivity. While there are differences in the doping dependence of the modulation wave vectors in YBa2Cu3O6+x and La2-xBaxCuO4, the maximum ordering strength is peaked at the hole concentration of 1/8 in both cases. There are also possible connections with the quantum oscillations that have been detected about the same hole concentration but at high magnetic fields. Resolving these relationships remains a research challenge.

  2. Direct measurement of the upper critical field in cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Grissonnanche, G.; Cyr-Choinière, O.; Laliberté, F.; René de Cotret, S.; Juneau-Fecteau, A.; Dufour-Beauséjour, S.; Delage, M.-È.; Leboeuf, D.; Chang, J.; Ramshaw, B. J.; Bonn, D. A.; Hardy, W. N.; Liang, R.; Adachi, S.; Hussey, N. E.; Vignolle, B.; Proust, C.; Sutherland, M.; Krämer, S.; Park, J.-H.; Graf, D.; Doiron-Leyraud, N.; Taillefer, Louis

    2014-02-01

    In the quest to increase the critical temperature Tc of cuprate superconductors, it is essential to identify the factors that limit the strength of superconductivity. The upper critical field Hc2 is a fundamental measure of that strength, yet there is no agreement on its magnitude and doping dependence in cuprate superconductors. Here we show that the thermal conductivity can be used to directly detect Hc2 in the cuprates YBa2Cu3Oy, YBa2Cu4O8 and Tl2Ba2CuO6+δ, allowing us to map out Hc2 across the doping phase diagram. It exhibits two peaks, each located at a critical point where the Fermi surface of YBa2Cu3Oy is known to undergo a transformation. Below the higher critical point, the condensation energy, obtained directly from Hc2, suffers a sudden 20-fold collapse. This reveals that phase competition—associated with Fermi-surface reconstruction and charge-density-wave order—is a key limiting factor in the superconductivity of cuprates.

  3. Impedance and dielectric properties of mercury cuprate at nonsuperconducting state

    NASA Astrophysics Data System (ADS)

    Özdemir, Z. Güven; Çataltepe, Ö. Aslan; Onbaşlı, Ü.

    2015-10-01

    In this paper, impedance and dielectric properties of nonsuperconducting state of the mercury-based cuprate have been investigated by impedance measurements within the frequency interval of 10 Hz-10 MHz for the first time. The dielectric loss factor (tgδ) and ac conductivity (σac) parameters have also been calculated for non-superconducting state. According to impedance spectroscopy analysis, the equivalent circuit of the mercury cuprate system manifests itself as a semicircle in the Nyquist plot that corresponds to parallel connected resistance-capacitance circuit. The oscillation frequency of the circuit has been determined as approximately 45 kHz which coincides with the low frequency radio waves. Moreover, it has been revealed that the mercury-based cuprate investigated has high dielectric constants and hence it may be utilized in microelectronic industry such as capacitors, memory devices etc., at room temperature. In addition, negative capacitance (NC) effect has been observed for the mercury cuprate regardless of the operating temperatures at nonsuperconducting state. Referring to dispersions in dielectric properties, the main contribution to dielectric response of the system has been suggested as dipolar and interfacial polarization mechanisms.

  4. Insights on the Cuprate High Energy Anomaly Observed in ARPES

    SciTech Connect

    Moritz, Brian

    2011-08-16

    Recently, angle-resolved photoemission spectroscopy has been used to highlight an anomalously large band renormalization at high binding energies in cuprate superconductors: the high energy 'waterfall' or high energy anomaly (HEA). The anomaly is present for both hole- and electron-doped cuprates as well as the half-filled parent insulators with different energy scales arising on either side of the phase diagram. While photoemission matrix elements clearly play a role in changing the aesthetic appearance of the band dispersion, i.e. creating a 'waterfall'-like appearance, they provide an inadequate description for the physics that underlies the strong band renormalization giving rise to the HEA. Model calculations of the single-band Hubbard Hamiltonian showcase the role played by correlations in the formation of the HEA and uncover significant differences in the HEA energy scale for hole- and electron-doped cuprates. In addition, this approach properly captures the transfer of spectral weight accompanying doping in a correlated material and provides a unifying description of the HEA across both sides of the cuprate phase diagram. We find that the anomaly demarcates a transition, or cross-over, from a quasiparticle band at low binding energies near the Fermi level to valence bands at higher binding energy, assumed to be of strong oxygen character.

  5. Direct measurement of the upper critical field in cuprate superconductors

    PubMed Central

    Grissonnanche, G.; Cyr-Choinière, O.; Laliberté, F.; René de Cotret, S.; Juneau-Fecteau, A.; Dufour-Beauséjour, S.; Delage, M. -È.; LeBoeuf, D.; Chang, J.; Ramshaw, B. J.; Bonn, D. A.; Hardy, W. N.; Liang, R.; Adachi, S.; Hussey, N. E.; Vignolle, B.; Proust, C.; Sutherland, M.; Krämer, S.; Park, J. -H.; Graf, D.; Doiron-Leyraud, N.; Taillefer, Louis

    2014-01-01

    In the quest to increase the critical temperature Tc of cuprate superconductors, it is essential to identify the factors that limit the strength of superconductivity. The upper critical field Hc2 is a fundamental measure of that strength, yet there is no agreement on its magnitude and doping dependence in cuprate superconductors. Here we show that the thermal conductivity can be used to directly detect Hc2 in the cuprates YBa2Cu3Oy, YBa2Cu4O8 and Tl2Ba2CuO6+δ, allowing us to map out Hc2 across the doping phase diagram. It exhibits two peaks, each located at a critical point where the Fermi surface of YBa2Cu3Oy is known to undergo a transformation. Below the higher critical point, the condensation energy, obtained directly from Hc2, suffers a sudden 20-fold collapse. This reveals that phase competition—associated with Fermi-surface reconstruction and charge-density-wave order—is a key limiting factor in the superconductivity of cuprates. PMID:24518054

  6. Ultrafast studies of coexisting electronic order in cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Hinton, James; Thewalt, Eric; Alpichshev, Zhanybek; Sternbach, Aaron; McLeod, Alex; Ji, L.; Veit, Mike; Dorrow, Chelsey; Koralek, Jake; Xhao, Xudong; Barisic, Neven; Kemper, Alexander; Gedik, Nuh; Greven, Martin; Basov, Dimitri; Orenstein, Joe

    The cuprate family of high temperature superconductors displays a variety of electronic phases which emerge when charge carriers are added to the antiferromagnetic parent compound. These electronic phases are characterized by subtle differences in the low energy electronic excitations. Ultrafast time-resolved reflectivity (TRR) provides an ideal tool for investigating the cuprate phase diagram, as small changes in the electronic structure can produce significant contrast in the non-equilibrium reflectivity. Here we present TRR measurements of cuprate superconductors, focusing on the model single-layer cuprate HgBa2CuO4+δ. We observe a cusp-like feature in the quasiparticle lifetime near the superconducting transition temperature Tc. This feature can be understood using a model of coherently-mixed charge-density wave and superconducting pairing. We propose extending this technique to the nanoscale using ultrafast scattering scanning near-field microscopy (u-SNOM). This will allow us to explore how these electronic phases coexist and compete in real-space.

  7. Phase Separation in Cuprate Superconductors - Proceedings of the Workshop

    NASA Astrophysics Data System (ADS)

    Müller, K. A.; Benedek, G.

    1993-01-01

    The Table of Contents for the full book PDF is as follows: * Preface and Scope * Frustrated Phase Separation and High Temperature Superconductivity * Phase Separation and Photo-Induced High Tc Superconductivity in the Cuprates * Neutron Scattering Studies of the Spin Dynamics in La2-xSrxCuO4 * Percolative Phase Separation and High Tc Superconductivity * Phase Separation in Cuprate Superconductors from NMR and Microwave Absorption Measurements * Electronic Structure and Phase Separation in Superconducting Cuprates * The Virtual Exciton Mechanism of Superconductivity * Linear Arrays of Non Homogeneous Cu Sites in the CuO2 Plane: A New Scenario for Pairing Mechanisms in a Corrugated-Iron-Like Plane * Phase Separation, Structure and Superconductivity in Oxygen-Annealed La2CuO4+δ * Phase Separation in La2-xSrxCuO4 and YBa2Cu3Ox Studied by Mössbauer Spectroscopy * Phase Diagram and Transport Studies on La2-xSrxCuO4 * Static and Dynamic Transport Aspects of Phase Separation * Phase Separation in the Superconducting La2Cu4+δ Phases (0 < δ < 0.09) Prepared by Electrochemical Oxidation * Neutron Scattering Study of the YBa2Cu3O6+x System * NMR Investigation of Low Energy Excitations in YBa2Cu3O6+x Single Crystals * Aspects of the Spin Dynamics in the Cuprate Superconductors * Oxygen Order and Spin Structure in YBa2Cu3Ox Deduced from Copper NMR and NQR * Static and Dynamic Magnetic Properties of Ba, Cu and O in YBa2Cu4O8 and Y2Ba4Cu7O15.1 * Positional Splitting of Apex Oxygen and Nonlinear Excitations in Cuprates * Cooper Pair Formation by Distortive Electron-Lattice Coupling * Bipolaronic Charge Density Waves, Polaronic Spin Density Waves, and High Tc Superconductivity * Phase Separation as Result of a Thermodynamical Variational Method for the Emery Model * General Discussion led by G. Benedek and K. A. Müller

  8. Chiral plaquette polaron theory of cuprate superconductivity

    NASA Astrophysics Data System (ADS)

    Tahir-Kheli, Jamil; Goddard, William A., III

    2007-07-01

    Ab initio density functional calculations on explicitly doped La2-xSrxCuO4 find that doping creates localized holes in out-of-plane orbitals. A model for cuprate superconductivity is developed based on the assumption that doping leads to the formation of holes on a four-site Cu plaquette composed of the out-of-plane A1 orbitals apical Opz , planar Cud3z2-r2 , and planar Opσ . This is in contrast to the assumption of hole doping into planar Cudx2-y2 and Opσ orbitals as in the t-J model. Allowing these holes to interact with the d9 spin background leads to chiral polarons with either a clockwise or anticlockwise charge current. When the polaron plaquettes percolate through the crystal at x≈0.05 for La2-xSrxCuO4 , a Cudx2-y2 and planar Opσ band is formed. The computed percolation doping of x≈0.05 equals the observed transition to the “metallic” and superconducting phase for La2-xSrxCuO4 . Spin exchange Coulomb repulsion with chiral polarons leads to d -wave superconducting pairing. The equivalent of the Debye energy in phonon superconductivity is the maximum energy separation between a chiral polaron and its time-reversed partner. This energy separation is on the order of the antiferromagnetic spin coupling energy, Jdd˜0.1eV , suggesting a higher critical temperature. An additive skew-scattering contribution to the Hall effect is induced by chiral polarons and leads to a temperature dependent Hall effect that fits the measured values for La2-xSrxCuO4 . The integrated imaginary susceptibility, observed by neutron spin scattering, satisfies ω/T scaling due to chirality and spin-flip scattering of polarons along with a uniform distribution of polaron energy splittings. The derived functional form is compatible with experiments. The static spin structure factor for chiral spin coupling of the polarons to the undoped antiferromagnetic Cud9 spins is computed for classical spins on large two-dimensional lattices and is found to be incommensurate with a

  9. New avenues in the directed deprotometallation of aromatics: recent advances in directed cupration.

    PubMed

    Harford, Philip J; Peel, Andrew J; Chevallier, Floris; Takita, Ryo; Mongin, Florence; Uchiyama, Masanobu; Wheatley, Andrew E H

    2014-10-14

    Recent advances in the selective deprotometallation of aromatic reagents using alkali metal cuprates are reported. The ability of these synergic bases to effect deprotonation under the influence of a directing group is explored in the context of achieving new and more efficient organic transformations whilst encouraging greater ancillary group tolerance by the base. Developments in our understanding of the structural chemistry of alkali metal cuprates are reported, with both Gilman cuprates of the type R2CuLi and Lipshutz and related cuprates of the type R2Cu(X)Li2 (X = inorganic anion) elucidated and rationalised in terms of ligand sterics. The generation of new types of cuprate motif are introduced through the development of adducts between different classes of cuprate. The use of DFT methods to interrogate the mechanistic pathways towards deprotonative metallation is described. Theoretical modelling of in situ rearrangements undergone by the cuprate base are discussed, with a view to understanding the relationship between R2CuLi and R2Cu(X)Li2, their interconversion and the implications of this for cuprate reactivity. The advent of a new class of adduct between different cuprate types is developed and interpreted in terms of the options for expelling LiX from R2Cu(X)Li2. Applications in the field of medicinal chemistry and (hetero)arene derivatization are explored. PMID:24919957

  10. Enhanced Superconductivity in Superlattices of high-$T_c$ Cuprates

    SciTech Connect

    Okamoto, Satoshi; Maier, Thomas A

    2008-01-01

    The electronic properties of multilayers of strongly-correlated models for cuprate superconductors are investigated using cluster dynamical mean-field techniques. We focus on combinations of under-doped and over-doped layers and find that the superconducting order parameter in the over-doped layers is enhanced by the proximity effect of the strong pairing scale originating from the under-doped layers. The enhanced order parameter can even exceed the maximum value in uniform systems. This behavior is well reproduced in slave-boson mean-field calculations which also find higher transition temperatures than in the uniform system. These results indicate the possibility for higher critical temperatures in artificial cuprate multilayer systems.

  11. Inhomogeneities in single crystals of cuprate oxide superconductors

    NASA Technical Reports Server (NTRS)

    Moorjani, K.; Bohandy, J.; Kim, B. F.; Adrian, F. J.

    1991-01-01

    The next stage in the evolution of experimental research on the high temperature superconductors will require high quality single crystals and epitaxially grown crystalline films. However, inhomogeneities and other defects are not uncommon in single crystals of cuprate oxide superconductors, so a corollary requirement will be a reliable method for judging the quality of these materials. The application of magnetically modulated resistance methods in this task is briefly described and illustrated.

  12. Puzzles about 1/8 magic doping in cuprate

    NASA Astrophysics Data System (ADS)

    Feng, D. L.; Shen, Z.-X.; Zhou, X. J.; Shen, K. M.; Lu, D. H.; Marel, D. V. D.

    2006-01-01

    We discuss the puzzles surrounding the interpretation of the 1/8 anomaly in cuprates, highlighting the tension between the real and reciprocal space ways to look at the problem. This issue is relevant to the current discussion on the nature of charge ordering in the form of ‘stripe’ and ‘checker-board’ as derived from neutron and STM experiments. A resolution of this tension is important to fully understand the electronic structure.

  13. Experimental Evidence for Topological Doping in the Cuprates

    SciTech Connect

    Tranquada, J. M.

    1999-04-06

    Some recent experiments that provide support for the concept of topological doping in cuprate superconductors are discussed. Consistent with the idea of charge segregation, it is argued that the scattering associated with the ''resonance'' peak found in YBa{sub 2}Cu{sub 3}O{sub 6+x} and Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} comes from the Cu spins and not from the doped holes.

  14. Superconducting Clusters and Colossal Effects in Underdoped Cuprates

    NASA Astrophysics Data System (ADS)

    Alvarez, Gonzalo; Mayr, Matthias; Moreo, Adriana

    2005-03-01

    Phenomenological models for the antiferromagnetic vs. d-wave superconductivity competition in cuprates are studied[1] using conventional Monte Carlo techniques. The analysis suggests that cuprates may show a variety of different behaviors in the very underdoped regime: local coexistence, stripes, or, if disorder is present, states with nanoscale superconducting clusters. The transition from an antiferromagnetic to a superconducting state does not seem universal. In particular, inhomogeneous states lead to the possibility of colossal effects in some cuprates, analogous of those in manganites. Under suitable conditions, non-superconducting Cu-oxides could rapidly[2] become superconducting by the influence of weak perturbations that align the randomly oriented phases of the superconducting clusters in the mixed state. Consequences of these ideas for angle resolved photoemission and scanning tunneling microscopy experiments[3] will also discussed. [1] Alvarez et al., cond-mat/0401474, to appear in PRB. [2] I. Bozovic et al., PRL 93, 157002, (2004) [3] A. Ino et al., PRB 62, 4127 (2000); K. Lang et al, Nature 415, 412 (2002). Research performed in part at the Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy under Contract DE-AC05-00OR22725.

  15. Doping dependence of Meissner effect in cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Feng, Shiping; Huang, Zheyu; Zhao, Huaisong

    2010-11-01

    Within the t- t‧- J model, the doping dependence of the Meissner effect in cuprate superconductors is studied based on the kinetic energy driven superconducting mechanism. Following the linear response theory, it is shown that the electromagnetic response consists of two parts, the diamagnetic current and the paramagnetic current, which exactly cancels the diamagnetic term in the normal state, and then the Meissner effect is obtained for all the temperature T ⩽ Tc throughout the superconducting dome. By considering the two-dimensional geometry of cuprate superconductors within the specular reflection model, the main features of the doping and temperature dependence of the local magnetic field profile, the magnetic field penetration depth, and the superfluid density observed on cuprate superconductors are well reproduced. In particular, it is shown that in analogy to the domelike shape of the doping dependent superconducting transition temperature, the maximal superfluid density occurs around the critical doping δ ≈ 0.195, and then decreases in both lower doped and higher doped regimes.

  16. Sr2IrO4: Gateway to cuprate superconductivity?

    SciTech Connect

    Mitchell, J. F.

    2015-06-05

    High temperature superconductivity in cuprates remains a defining challenge in condensed matter physics. Recently, a new set of related compounds based on Ir rather than Cu has been discovered that may be on the verge of superconductivity themselves or be able to shed new light on the underlying interactions responsible for superconductivity in the cuprates.

  17. Atomic-Layer Engineering of Cuprate Superconductors (415th Brookhaven Lecture)

    SciTech Connect

    Bozovic, Ivan

    2006-05-17

    Copper-oxide compounds, called cuprates, show superconducting properties at 163 degrees Kelvin, the highest temperature of any known superconducting material. Cuprates are therefore among the 'high-temperature superconductors' of extreme interest both to scientists and to industry. Research to learn their secrets is one of the hottest topics in the field of materials science.

  18. 40 CFR 721.10488 - Cuprate, [[[[[[[ (sulfonaphthalenyl)]azo]-(substitutedphenyl)]azo]-(substitutedsulfonaphthalenyl...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Cuprate, azo]-(substitutedphenyl)]azo]-(substitutedsulfonaphthalenyl)] azo] - substituted phenyl - substituted heteromonocycle], sodium salts (generic). 721.10488... Substances § 721.10488 Cuprate, azo]-(substitutedphenyl)]azo]-(substitutedsulfonaphthalenyl)]...

  19. 40 CFR 721.10488 - Cuprate, [[[[[[[ (sulfonaphthalenyl)]azo]- (substitutedphenyl)]azo...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Cuprate, azo]- (substitutedphenyl)]azo]- (substitutedsulfonaphthalenyl)] azo]- substituted phenyl- substituted heteromonocycle], sodium salts (generic). 721.10488... Substances § 721.10488 Cuprate, azo]- (substitutedphenyl)]azo]- (substitutedsulfonaphthalenyl)]...

  20. Direct Hydroxylation and Amination of Arenes via Deprotonative Cupration.

    PubMed

    Tezuka, Noriyuki; Shimojo, Kohei; Hirano, Keiichi; Komagawa, Shinsuke; Yoshida, Kengo; Wang, Chao; Miyamoto, Kazunori; Saito, Tatsuo; Takita, Ryo; Uchiyama, Masanobu

    2016-07-27

    Deprotonative directed ortho cupration of aromatic/heteroaromatic C-H bond and subsequent oxidation with t-BuOOH furnished functionalized phenols in high yields with high regio- and chemoselectivity. DFT calculations revealed that this hydroxylation reaction proceeds via a copper (I → III → I) redox mechanism. Application of this reaction to aromatic C-H amination using BnONH2 efficiently afforded the corresponding primary anilines. These reactions show broad scope and good functional group compatibility. Catalytic versions of these transformations are also demonstrated. PMID:27348154

  1. Thermomagnetic effects above and below {Tc} in the cuprate superconductors

    SciTech Connect

    Clayhold, J.A.; Xue, Y.Y.; Chu, C.W.; Eckstein, J.N.; Bozovic, I.

    1996-12-31

    Two different thermomagnetic transport quantities, the electrothermal conductivity and the Nernst effect are shown to be powerful probes of high-temperature superconductors. In the vortex state below {Tc}, the electrothermal conductivity is independent of both the magnetic field and the vortex viscosity because it is sensitive only to the properties of the vortex normal cores. Some new data from cuprate superconductors show a surprising, low-field anomaly in the dilute vortex limit. Above {Tc} in the normal state, it is shown how the Nernst effect is a probe of transport anisotropy around the Fermi surface.

  2. Atomic layer-by-layer epitaxy of cuprate superconductors

    SciTech Connect

    Bozovic, I.; Eckstein, J.N.; Virshup, G.F.

    1994-03-01

    A technique for atomic layer-by-layer epitaxy of cuprate superconductors and other complex oxides has been developed at Varian. The samples are engineered by stacking molecular layers of different compounds to assemble multilayers and superlattices, by adding or omitting atomic monolayers to create novel compounds, and by doping within specified atomic monolayers. Apart form manufacturing trilayer Josephson junctions with I{sub c}R{sub n}>5 mV, this technique enables one to address fundamental issues such as the dimensionality of HTSC state, existence of long-range proximity effects, occurrence of resonant tunneling etc., as well as to synthesize novel metastable HTSC compounds. 4 refs., 2 figs.

  3. Cold-spots and glassy nematicity in underdoped cuprates

    NASA Astrophysics Data System (ADS)

    Lee, Kyungmin; Kivelson, Steven A.; Kim, Eun-Ah

    2016-07-01

    There is now copious direct experimental evidence of various forms of (short-range) charge order in underdoped cuprate high temperature superconductors, and spectroscopic signatures of a nodal-antinodal dichotomy in the structure of the single-particle spectral functions. In this context we analyze the Bogoliubov quasiparticle spectrum in a superconducting nematic glass. The coincidence of the superconducting "nodal points" and the nematic "cold-spots" on the Fermi surface naturally accounts for many of the most salient features of the measured spectral functions (from angle-resolved photoemission) and the local density of states (from scanning tunneling microscopy).

  4. Hidden Fermionic Excitation Boosting High-Temperature Superconductivity in Cuprates.

    PubMed

    Sakai, Shiro; Civelli, Marcello; Imada, Masatoshi

    2016-02-01

    The dynamics of a microscopic cuprate model, namely, the two-dimensional Hubbard model, is studied with a cluster extension of the dynamical mean-field theory. We find a nontrivial structure of the frequency-dependent self-energies, which describes an unprecedented interplay between the pseudogap and superconductivity. We show that these properties are well described by quasiparticles hybridizing with (hidden) fermionic excitations, emergent from the strong electronic correlations. The hidden fermion enhances superconductivity via a mechanism distinct from a conventional boson-mediated pairing, and originates the normal-state pseudogap. Though the hidden fermion is elusive in experiments, it can solve many experimental puzzles. PMID:26894730

  5. Hidden Fermionic Excitation Boosting High-Temperature Superconductivity in Cuprates

    NASA Astrophysics Data System (ADS)

    Sakai, Shiro; Civelli, Marcello; Imada, Masatoshi

    2016-02-01

    The dynamics of a microscopic cuprate model, namely, the two-dimensional Hubbard model, is studied with a cluster extension of the dynamical mean-field theory. We find a nontrivial structure of the frequency-dependent self-energies, which describes an unprecedented interplay between the pseudogap and superconductivity. We show that these properties are well described by quasiparticles hybridizing with (hidden) fermionic excitations, emergent from the strong electronic correlations. The hidden fermion enhances superconductivity via a mechanism distinct from a conventional boson-mediated pairing, and originates the normal-state pseudogap. Though the hidden fermion is elusive in experiments, it can solve many experimental puzzles.

  6. Angle-resolved photoemission spectroscopy (ARPES) studies of cuprate superconductors

    SciTech Connect

    Palczewski, Ari Deibert

    2010-01-01

    This dissertation is comprised of three different angle-resolved photoemission spectroscopy (ARPES) studies on cuprate superconductors. The first study compares the band structure from two different single layer cuprates Tl2Ba2CuO6+δ (Tl2201) Tc, max ≈ 95 K and (Bi 1.35Pb0.85)(Sr1.47La0.38)CuO6+δ (Bi2201) Tc, max ≈ 35 K. The aim of the study was to provide some insight into the reasons why single layer cuprate's maximum transition temperatures are so different. The study found two major differences in the band structure. First, the Fermi surface segments close to (π,0) are more parallel in Tl2201 than in Bi2201. Second, the shadow band usually related to crystal structure is only present in Bi2201, but absent in higher Tc Tl2201. The second study looks at the different ways of doping Bi2Sr2CaCu2O8+δ (Bi2212) in-situ by only changing the post bake-out vacuum conditions and temperature. The aim of the study is to systematically look into the generally overlooked experimental conditions that change the doping of a cleaved sample in ultra high vacuum (UHV) experiments. The study found two major experimental facts. First, in inadequate UHV conditions the carrier concentration of Bi2212 increases with time, due to the absorption of oxygen from CO2/CO molecules, prime contaminants present in UHV systems. Second, in a very clean UHV system at elevated temperatures (above about 200 K), the carrier concentration decreases due to the loss of oxygen atoms from the Bi-O layer. The final study probed the particle-hole symmetry of the pseudogap phase in high temperature superconducting cuprates by looking at the thermally excited bands above the Fermi level. The data showed a particle-hole symmetric pseudogap which symmetrically closes away from the nested FS before the node. The data is consistent

  7. Quasiparticles in the pseudogap Phase of Underdoped Cuprate

    SciTech Connect

    Yang, K.; Yang, H; Johnson, P; Rice, T; Zhang, F

    2009-01-01

    Recent angle-resolved photoemission (Yang H.-B. et al., Nature, 456 (2008) 77) and scanning tunneling microscopy (Kohsaka Y. et al., Nature, 454 (2008) 1072) measurements on underdoped cuprates have yielded new spectroscopic information on quasiparticles in the pseudogap phase. New features of the normal state such as particle-hole asymmetry, maxima in the energy dispersion, and accompanying drops in the spectral weight of quasiparticles agree with the ansatz of Yang et al. for the single-particle propagator in the pseudogap phase. The coherent quasiparticle dispersion and reduced asymmetry in the tunneling density of states in the superconducting state can also be described by this propagator.

  8. Ong construction for the reconstructed Fermi surface of underdoped cuprates

    NASA Astrophysics Data System (ADS)

    Robinson, P.; Hussey, N. E.

    2015-12-01

    Using the Ong construction for a two-dimensional metal, we show that the sign change in the Hall coefficient RH of underdoped hole-doped cuprates at low temperature is consistent with the emergence of biaxial charge order recently proposed to explain the observation of low-frequency quantum oscillations. The sharp evolution of RH with temperature, however, can only be reconciled by incorporating a highly anisotropic quasiparticle scattering rate. The magnitude and form of the scattering rate extracted from the fitting imply that those quasiparticles at the vertices of the reconstructed pocket(s) approach the boundary of incoherence at the onset of charge order.

  9. Paired electron pockets in the hole-doped cuprates

    NASA Astrophysics Data System (ADS)

    Galitski, Victor; Sachdev, Subir

    2009-04-01

    We propose a theory for the underdoped hole-doped cuprates, focusing on the “nodal-antinodal dichotomy” observed in recent experiments. Our theory begins with an ordered antiferromagnetic Fermi liquid with electron and hole pockets. We argue that it is useful to consider a quantum transition at which the loss of antiferromagnetic order leads to a hypothetical metallic “algebraic charge liquid” (ACL) with pockets of charge -e and +e fermions, and an emergent U(1) gauge field; the instabilities of the ACL lead to the low-temperature phases of the underdoped cuprates. The pairing instability leads to a superconductor with the strongest pairing within the -e Fermi pockets, a d -wave pairing signature for electrons, and very weak nodal-point pairing of the +e fermions near the Brillouin-zone diagonals. The influence of an applied magnetic field is discussed using a proposed phase diagram as a function of field strength and doping. We describe the influence of gauge field and pairing fluctuations on the quantum Shubnikov-de Haas oscillations in the normal states induced by the field. For the finite-temperature pseudogap region, our theory has some similarities to the phenomenological two-fluid model of -2e bosons and +e fermions proposed by Geshkenbein [Phys. Rev. B 55, 3173 (1997)], which describes anomalous aspects of transverse transport in a magnetic field.

  10. Fluctuating charge-density waves in a cuprate superconductor.

    PubMed

    Torchinsky, Darius H; Mahmood, Fahad; Bollinger, Anthony T; Božović, Ivan; Gedik, Nuh

    2013-05-01

    Cuprate materials hosting high-temperature superconductivity (HTS) also exhibit various forms of charge and spin ordering whose significance is not fully understood. So far, static charge-density waves (CDWs) have been detected by diffraction probes only at particular doping levels or in an applied external field . However, dynamic CDWs may also be present more broadly and their detection, characterization and relationship with HTS remain open problems. Here we present a method based on ultrafast spectroscopy to detect the presence and measure the lifetimes of CDW fluctuations in cuprates. In an underdoped La(1.9)Sr(0.1)CuO4 film (T(c) = 26 K), we observe collective excitations of CDW that persist up to 100 K. This dynamic CDW fluctuates with a characteristic lifetime of 2 ps at T = 5 K that decreases to 0.5 ps at T = 100 K. In contrast, in an optimally doped La(1.84)Sr(0.16)CuO4 film (T(c) = 38.5 K), we detect no signatures of fluctuating CDWs at any temperature, favouring the competition scenario. This work forges a path for studying fluctuating order parameters in various superconductors and other materials. PMID:23435216

  11. Hybrid crystals of cuprates and iron-based superconductors

    NASA Astrophysics Data System (ADS)

    Xia, Dai; Cong-Cong, Le; Xian-Xin, Wu; Jiang-Ping, Hu

    2016-07-01

    We propose two possible new compounds, Ba2CuO2Fe2As2 and K2CuO2Fe2Se2, which hybridize the building blocks of two high temperature superconductors, cuprates and iron-based superconductors. These compounds consist of square CuO2 layers and antifluorite-type Fe2 X 2 (X = As, Se) layers separated by Ba/K. The calculations of binding energies and phonon spectra indicate that they are dynamically stable, which ensures that they may be experimentally synthesized. The Fermi surfaces and electronic structures of the two compounds inherit the characteristics of both cuprates and iron-based superconductors. These compounds can be superconductors with intriguing physical properties to help to determine the pairing mechanisms of high T c superconductivity. Project supported by the National Basic Research Program of China (Grant No. 2015CB921300), the National Natural Science Foundation of China (Grant Nos. 1190020 and 11334012), and the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB07000000).

  12. 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.

  13. Lorenz number in cuprates: digital evidence for bipolarons

    NASA Astrophysics Data System (ADS)

    Alexandrov, Sasha

    2003-03-01

    Strong electron-phonon interaction in the cuprates has gathered support over the last decade in a number of experiments. While phonons remain almost unrenormalised, electrons are transformed into itinerant bipolarons and thermally excited polarons when the electron-phonon interaction is strong. We calculate the Lorenz number of the system to show that the Wiedemann-Franz law breaks down because of the interference of polaron and bipolaron contributions in the heat flow [1]. The model fits numerically the experimental Hall Lorenz number [2], which provides a digital evidence for bipolarons in the cuprates. *Mailing address: Department of Physics, Loughborough University, Loughborough LE11 3TU, United Kingdom; E-mail: a.s.alexandrov@lboro.ac.uk; Phone: (44) 1509 223303; Fax: (44) 1509 223986. [1] K. K. Lee, W. Y. Liang, A. S. Alexandrov (2002) unpublished. [2] Y. Zhang, N.P. Ong, Z.A. Xu, K. Krishana, R. Gagnon, and L.Taillefer, Phys. Rev. Lett., 84, 2219 (2000).

  14. Searching for spectroscopic signatures of density wave correlations in cuprates

    NASA Astrophysics Data System (ADS)

    He, Rui-Hua

    2015-03-01

    Recent developments in the research on high-temperature cuprate superconductors highlight the relevance of some density wave correlations to the superconductivity and its normal state in this generic class of materials. Depending on specific cuprate systems, these density wave correlations can have diverse manifestations in different (charge, spin, pairing) sectors and likely break (time reversal, space inversion, point group, gauge) symmetries in addition to the lattice translation. A unified understanding of their microscopic nature hinges on further characterizations using direct (imaging scattering) probes for these correlations themselves, as well as indirect probes for their interplay with other degrees of freedom in the system. ARPES can provide information about a density wave order through probing modifications in the electron structure it induces, while other spectroscopy techniques can shed unique lights on the broken symmetry aspect of the order. In this talk, I will review the density-wave signatures that have been or yet to be found in ARPES mainly in terms of the spectral weight, energy gap, and renormalized band dispersions. These experimental observations/proposals, coupled with simple theoretical modeling, promise new insights into the (wavevector, order parameter, form factor) characters of associated density wave correlations. Time permitting, I will introduce a novel x-ray spectroscopy technique that can detect broken time-reversal versus space-inversion symmetry of an electronic order in a way complementary to the polar Kerr effect.

  15. μSR Studies on Magnetism in High-Tc Cuprates

    NASA Astrophysics Data System (ADS)

    Koike, Yoji; Adachi, Tadashi

    2016-09-01

    Since the discovery of high-Tc superconductivity in cuprates, muon spin relaxation (μSR) measurements have greatly contributed to the understanding of high-Tc superconductivity. In this paper, μSR studies on the magnetism in high-Tc cuprates obtained these past three decades are reviewed. Antiferromagnetic long-range order, 1/8 anomaly, stripes of Cu spins and holes, impurity-induced magnetism, magnetic-field-induced magnetism, pseudogap, ferromagnetism in the heavily overdoped regime, and undoped superconductivity in T'-type cuprates are discussed. Moreover, the fundamentals of μSR measurements for the study of magnetism are described for μSR beginners.

  16. Anticorrelation between the parent charge transfer gap and maximum transition temperature in cuprates

    NASA Astrophysics Data System (ADS)

    Ruan, Wei; Hu, Cheng; Cai, Peng; Peng, Yingying; Li, Xintong; Hao, Zhenqi; Zhou, Xingjiang; Weng, Zheng-Yu; Wang, Yayu

    We use scanning tunneling spectroscopy to measure the electronic structure of the parent Mott insulator of three different types of cuprates. The charge transfer gap size exhibits pronounced variations, and more interestingly it shows an anticorrelation with the maximum superconducting transition temperature achieved at the optimal doping of each cuprate. This result suggests that the Mottness in parent cuprate plays a crucial role in determining the superconducting properties. In particular, reducing the electron correlation strength enhances superconductivity, which is consistent with the pairing mechanism based on the doped Mott insulator picture.

  17. Role of Pressure and Magnetic Scattering on the Tc of the Cuprates

    NASA Astrophysics Data System (ADS)

    Wolf, Stuart; Kresin, Vladimir; Ovchinnikov, Yurii

    1996-03-01

    We can show that the large pressure effects on the transition temperature in the superconducting cuprates are caused by an unusual interplay between carrier doping and pair-breaking scattering. This pair-breaking scattering leads to a depression of Tc relative to its intrinsic value which we find to be in the range of 160K. Using these ideas we can explain the relative transition temperature in the one, two, and three layer cuprates as well as estimate the maximum Tc for the cuprate family of superconductors.

  18. The microscopic structure of charge order in cuprates

    NASA Astrophysics Data System (ADS)

    Comin, Riccardo

    2015-03-01

    The spontaneous self-arrangement of electrons into periodically modulated patterns, a phenomenon commonly termed as charge order or charge-density-wave (CDW), has recently resurfaced as a prominent, universal ingredient for the physics of high-temperature superconductors. In such context, resonant x-ray scattering (RXS) has rapidly become the technique of choice for the study of charge order in momentum space, owing to its ability to directly identify a breaking of translational symmetry in the electronic density. In this talk, I will present our recent RXS studies of charge order in Bi2201, which reconciled years of apparently disconnected findings in different cuprate families by showing how charge order is a universal phenomenon in hole-doped cuprates [R. Comin, et al., Charge Order Driven by Fermi-Arc Instability in Bi2Sr2 - xLaxCuO6 +d, Science 343, 390 (2014)]. Contextually, I will discuss very recent findings of charge order in NCCO, which project such phenomenology to the electron-doped materials [E. da Silva Neto*, R. Comin*, et al., Charge ordering in the electron-doped superconductor Nd2-xCexCuO4, accepted (2014) - preprint at: http://arxiv.org/abs/1410.2253]. Furthermore, in YBCO, we have succeeded to fully reconstruct the CDW order parameter in the two-dimensional momentum space and demonstrate how resonant x-ray methods can be used to peer into the microscopic structure and symmetry of the charge order. Using this new method, we have been able to demonstrate the presence of charge stripes at the nanoscale [R. Comin, et al., Broken translational and rotational symmetry via charge stripe order in underdoped YBa2Cu3O6 +y, under review (2014)], as well as evaluate the local symmetry in the charge distribution around the Cu atoms, which was found to be predominantly of a d-wave bond-order type [R. Comin, et al., The symmetry of charge order in cuprates, under review (2014) - preprint at: http://arxiv.org/abs/1402.5415].

  19. Elastic moduli across the superconducting and pseudogap phase boundaries in four cuprate compounds

    NASA Astrophysics Data System (ADS)

    Ramshaw, Brad; Shekhter, Arkady; Betts, Jon; Migliori, Albert

    2013-03-01

    A detailed understanding of the physics of the cuprate superconductors relies on an experimental determination of the thermodynamic phase diagram. Resonant ultrasound spectroscopy (RUS) is a unique thermodynamic probe, capable of measuring part per million changes in elastic moduli, and has access to symmetry information. Here we present a symmetry analysis of changes in the elastic moduli across the superconducting and psedogap phase boundaries in several classes of cuprates: YBCO, LSCO, Hg-1201, and Tl-2201.

  20. Optical studies of high-temperature superconducting cuprates.

    PubMed

    Tajima, Setsuko

    2016-09-01

    The optical studies of high-temperature superconducting cuprates (HTSC) are reviewed. From the doping dependence of room temperature spectra, a dramatic change of the electronic state from a Mott (charge transfer) insulator to a Fermi liquid has been revealed. Additionally, the unusual 2D nature of the electronic state has been found. The temperature dependence of the optical spectra provided a rich source of information on the pseudogap, superconducting gap, Josephson plasmon, transverse Josephson plasma mode and precursory superconductivity. Among these issues, Josephson plasmons and transverse Josephson plasma mode were experimentally discovered by optical measurements, and thus are unique to HTSC. The effect of the spin/charge stripe order is also unique to HTSC, reflecting the conducting nature of the stripe order in this system. The pair-breaking due to the stripe order seems stronger in the out-of-plane direction than in the in-plane one. PMID:27472654

  1. Charge orders, magnetism and pairings in the cuprate superconductors.

    PubMed

    Kloss, T; Montiel, X; de Carvalho, V S; Freire, H; Pépin, C

    2016-08-01

    We review the recent developments in the field of cuprate superconductors with special focus on the recently observed charge order in the underdoped compounds. We introduce new theoretical developments following the study of the antiferromagnetic quantum critical point in two dimensions, in which preemptive orders in both charge and superconducting (SC) sectors emerge, that are in turn related by an SU(2) symmetry. We consider the implications of this proliferation of orders in the underdoped region, and provide a study of the type of fluctuations which characterize the SU(2) symmetry. We identify an intermediate energy scale where the SC fluctuations are dominant and argue that they are unstable towards the formation of a resonant excitonic state at the pseudogap temperature T (*). We discuss the implications of this scenario for a few key experiments. PMID:27427401

  2. Strong-coupling approach to nematicity in the cuprates

    NASA Astrophysics Data System (ADS)

    Orth, Peter Philipp; Jeevanesan, Bhilahari; Schmalian, Joerg; Fernandes, Rafael

    The underdoped cuprate superconductor YBa2Cu3O7-δ is known to exhibit an electronic nematic phase in proximity to antiferromagnetism. While nematicity sets in at large temperatures of T ~ 150 K, static spin density wave order only emerges at much lower temperatures. The magnetic response shows a strong in-plane anisotropy, displaying incommensurate Bragg peaks along one of the crystalline directions and a commensurate peak along the other one. Such an anisotropy persists even in the absence of long-range magnetic order at higher temperatures, marking the onset of nematic order. Here we theoretically investigate this situation using a strong-coupling method that takes into account both the localized Cu spins and the holes doped into the oxygen orbitals. We derive an effective spin Hamiltonian and show that charge fluctuations promote an enhancement of the nematic susceptibility near the antiferromagnetic transition temperature.

  3. Nonequilibrium phase transitions in cuprates observed by ultrafast electron crystallography.

    PubMed

    Gedik, Nuh; Yang, Ding-Shyue; Logvenov, Gennady; Bozovic, Ivan; Zewail, Ahmed H

    2007-04-20

    Nonequilibrium phase transitions, which are defined by the formation of macroscopic transient domains, are optically dark and cannot be observed through conventional temperature- or pressure-change studies. We have directly determined the structural dynamics of such a nonequilibrium phase transition in a cuprate superconductor. Ultrafast electron crystallography with the use of a tilted optical geometry technique afforded the necessary atomic-scale spatial and temporal resolutions. The observed transient behavior displays a notable "structural isosbestic" point and a threshold effect for the dependence of c-axis expansion (Deltac) on fluence (F), with Deltac/F = 0.02 angstrom/(millijoule per square centimeter). This threshold for photon doping occurs at approximately 0.12 photons per copper site, which is unexpectedly close to the density (per site) of chemically doped carriers needed to induce superconductivity. PMID:17446397

  4. Antiferromagnetic superconducting state in the electron-doped cuprates?

    NASA Astrophysics Data System (ADS)

    Das, Tanmoy; Markiewicz, Robert S.; Bansil, Arun

    2006-03-01

    Recent angle-resolved photoemission (ARPES) studies of the electron-doped cuprate Nd2-xCexCuO4 (NCCO)[1] have been interpreted in terms of a uniform antiferromagnetic (AF) metal, with doping into the upper magnetic band and gap collapse close to optimal doping[2]. An open question is whether the system remains uniform in the simultaneous presence of AF and (d- wave) superconducting (SC) order. Here, we explore the properties of a uniform AF-SC model for NCCO, to ascertain to what extent we can explain anomalous features, such as the nonmonotonic angle dependence of the superconducting gap[3]. Work supported by the USDOE. [1] N.P. Armitage, et al., PRL 87, 147003 (2002). [2] C. Kusko, et al., PRB66, 140513 (2002); A.-M.S. Tremblay, et al., cond-mat/0511334. [3] H. Matsui, et al., PRL 95, 017003 (2005).

  5. Optical studies of high-temperature superconducting cuprates

    NASA Astrophysics Data System (ADS)

    Tajima, Setsuko

    2016-09-01

    The optical studies of high-temperature superconducting cuprates (HTSC) are reviewed. From the doping dependence of room temperature spectra, a dramatic change of the electronic state from a Mott (charge transfer) insulator to a Fermi liquid has been revealed. Additionally, the unusual 2D nature of the electronic state has been found. The temperature dependence of the optical spectra provided a rich source of information on the pseudogap, superconducting gap, Josephson plasmon, transverse Josephson plasma mode and precursory superconductivity. Among these issues, Josephson plasmons and transverse Josephson plasma mode were experimentally discovered by optical measurements, and thus are unique to HTSC. The effect of the spin/charge stripe order is also unique to HTSC, reflecting the conducting nature of the stripe order in this system. The pair-breaking due to the stripe order seems stronger in the out-of-plane direction than in the in-plane one.

  6. A “midinfrared” scenario for cuprate superconductivity

    PubMed Central

    Leggett, A. J.

    1999-01-01

    I conjecture that the mechanism of superconductivity in the cuprates is a saving, due to the improved screening resulting from Cooper pair formation, of the part of the Coulomb energy associated with long wavelengths and midinfrared frequencies. This scenario is shown to provide a plausible explanation of the trend of transition temperature with layering structure in the Ca-spaced compounds and to predict a spectacularly large decrease in the electron-energy-loss spectroscopy cross-section in the midinfrared region on transition to the superconducting state, as well as less spectacular but still surprisingly large changes in the optical behavior. Existing experimental results appear to be consistent with this picture. PMID:10411881

  7. Charge orders, magnetism and pairings in the cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Kloss, T.; Montiel, X.; de Carvalho, V. S.; Freire, H.; Pépin, C.

    2016-08-01

    We review the recent developments in the field of cuprate superconductors with special focus on the recently observed charge order in the underdoped compounds. We introduce new theoretical developments following the study of the antiferromagnetic quantum critical point in two dimensions, in which preemptive orders in both charge and superconducting (SC) sectors emerge, that are in turn related by an SU(2) symmetry. We consider the implications of this proliferation of orders in the underdoped region, and provide a study of the type of fluctuations which characterize the SU(2) symmetry. We identify an intermediate energy scale where the SC fluctuations are dominant and argue that they are unstable towards the formation of a resonant excitonic state at the pseudogap temperature T *. We discuss the implications of this scenario for a few key experiments.

  8. Theoretical study of magnetoelectric effects in noncentrosymmetric and cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Kashyap, Manoj K.

    A century after the discovery of superconductivity at the lab of Kamerlingh Onnes in 1911, it is noticeable that the phenomenon is quite ubiquitous in nature. In addition to a long list of superconducting alloys and compounds, almost half the elements in the periodic table superconduct. By the late seventies, superconductivity was thought to be well understood. This turned out to be a myth, with the discovery of unconventional superconductors that defied Bardeen-Cooper-Schrieffer (BCS) theory. Cuprates have been the most prominent example among them ever since their discovery in 1986 by Bednorz and Muller. Another example of non-compliance with BCS theory lie among noncentrosymmetric superconductors. In this dissertation, magnetoelectric (ME) effects in these two classes of superconductors have been studied from different perspectives, utilizing Ginzburg-Landau (GL) theory. Even though GL theory was proposed before the BCS theory, it was not given much importance due to its phenomenological nature until Gor'kov proved that it is a limiting form of the microscopic BCS theory. However today, in the absence of any complete microscopic theory to explain superconductivity in unconventional superconductors, Ginzburg-Landau theory is an important tool to move ahead and qualitatively understand the behavior of varied superconducting systems. Noncentrosymmetric superconductors have generated much theoretical interest since 2004 despite been known for long. The absence of inversion symmetry in non- centrosymmetric superconductors allows for extra terms called Lifshitz invariants in the Ginzburg-Landau functional. This leads to magnetoelectric effects that do not exist in centrosymmetric superconductors. One manifestation of this is in the vortex structure in materials with a cubic point group O. In particular, a current is predicted to flow parallel to the applied magnetic field in such a vortex in addition to the usual vortex supercurrents. In this work, we present both

  9. Complete symmetry analysis of the Raman spectra in cuprates

    NASA Astrophysics Data System (ADS)

    Venturini, F.; Zhang, Q.-M.; Hackl, R.; Erb, A.; Berger, H.; Revaz, B.; Nagao, Y.; Ando, Y.

    2002-03-01

    We describe results of Raman scattering measurements on differently doped cuprate single crystals. We performed a complete polarization analysis, using circular in addition to the commonly used linear polarizations. This allowed us to determine all symmetry components of the Raman signal being characteristic for tetragonal systems, including A_2g excitations which indicate the presence of a time-reversal broken symmetry in these systems. The A_2g signal has an intensity comparable to that of the other symmetries, but exhibits a distinctly different frequency dependence. In particular, there is a gap at low energies which decreases with increasing doping. The Raman relaxation rates and mass renormalization factor extracted from the pure B_1g and B_2g spectra are consistent with IR-results, and the unphysical drop of 1+λ(ω) below unity for high frequencies disappears teopel. 99 opel M. Opel et al., Phys. Rev. B 61, 9752 (2000). thebibliography

  10. Effect of Extended Saddle Point Singularities in Cuprates and Evidences

    NASA Astrophysics Data System (ADS)

    Zhao, Guang-Lin

    First-principles calculations and angle-resolved photoemission spectroscopy measurements showed extended saddle point singularities in the electron structures of some cuprates such as YBa2Cu3O7 (YBCO). The extended saddle point singularities in the electronic structures of the materials can lead to anomalous physical properties. In this work, a new methodology is implemented by integrating first-principles calculations of electronic structures of the materials into the theory of many-body physics for superconductivity. The aim is to seek a unified methodology to calculate the electronic and superconducting properties of the materials. It is demonstrated from first-principles that the extended saddle point singularities in the materials such as YBCO strongly correlate to the anomalous isotope effect in the superconductors. The work was funded in part by NSF LASIGMA Project (Award # EPS-1003897, NSF92010-15-RII-SUBR) and by ARO (Award # W911NF-15-1-0483).

  11. Spin excitations of ferronematic order in underdoped cuprate superconductors

    PubMed Central

    Seibold, G.; Di Castro, C.; Grilli, M.; Lorenzana, J.

    2014-01-01

    High-temperature superconductors exhibit a characteristic hourglass-shaped spectrum of magnetic fluctuations which most likely contribute to the pairing glue in the cuprates. Recent neutron scattering experiments in strongly underdoped compounds have revealed a significant low energy anisotropy of these fluctuations which we explain by a model in which topological defects of the antiferromagnet clump to producing domain wall segments with ferronematic order. This state does not invoke global charge order but breaks C4 rotational and inversion symmetry. The incommensurability of the low doping charge-disordered state is in good agreement with experiment and interpolates smoothly with the incommensurability of the stripe phase at higher doping. Within linear spin-wave theory the dynamic structure factor is in very good agreement with inelastic neutron scattering data and can account for the observed energy dependent anisotropy. PMID:24936723

  12. Unconventional proximity effect and inverse spin-switch behavior in a model manganite-cuprate-manganite trilayer system

    SciTech Connect

    Salafranca Laforga, Juan I; Okamoto, Satoshi

    2010-01-01

    The proximity effect in a model manganite-cuprate system is investigated theoretically. We consider a situation in which spin-polarized electrons in manganite layers antiferromagnetically couple with electrons in cuprate layers as observed experimentally. The effect of the interfacial magnetic coupling is found to be much stronger than the injection of spin-polarized electrons into the cuprate region. As a result, the superconducting transition temperature depends on the thickness of the cuprate layer significantly. Since the magnetic coupling creates negative polarization, an applied magnetic field and the negative polarization compete, resulting in the inverse spin-switch behavior where the superconducting transition temperature is increased by applying a magnetic field.

  13. Liquid-gated superconductor-insulator transition in an electron-doped cuprate

    NASA Astrophysics Data System (ADS)

    Zeng, Shengwei; Huang, Zhen; Bao, Nina; Lv, Weiming; Liu, Zhiqi; Herng, T. S.; Gopinadhan, K.; Jian, Linke; Ding, J.; Venkatesan, T.; Ariando, Ariando

    2014-03-01

    Doping charge carriers will causes the change of cuprates from antiferromagnetic Mott insulators to high-Tc superconductors. Continuous changing of carrier density is necessary to understand the nature of such phase transition, and thus, further our understanding of cuprate superconductors. Electric field-effect doping, especially with electronic double layer transistors (EDLT) configuration which use ionic liquids (ILs) and polymer electrolyte as the gate dielectrics, is a potential avenue for this investigation and it has been shown its effectiveness in inducing phase transition in strongly correlated electron system. Owing to EDLT, superconductor-to-insulator transition (SIT) has been observed in hole-doped cuprates La2-xSrxCuO4 and YBa2Cu3Oy. Here we use EDLT to tune the carrier density in electron-doped cuprates Pr2-xCexCuO4 ultrathin films and cause the sample evolves from a superconducting state to an insulating state. This present results could be helpful to study SIT between electron- and hole-doped cuprates.

  14. Fermiology of the Undoped Cuprate Superconductor Pr2CuO4

    NASA Astrophysics Data System (ADS)

    McDonald, Ross; Breznay, Nicholas; Krockenberger, Yoshiharu; Modic, Kimberly; Zhu, Zengwei; Hayes, Ian; Nair, Nityan; Helm, Toni; Irie, Hiroshi; Yamamoto, Hideki; Analytis, James

    Unconventional, high temperature superconductivity consistently appears in the vicinity of suppressed phase transitions, leading to the suggestion that quantum criticality is vital to the physics of these systems. A confounding factor in identifying the role of quantum criticality in the electron-doped cuprates is the competing influence of chemical doping and oxygen stoichiometry. Recent advances in molecular beam epitaxy and preparation of cuprate thin films indicate that annealing can be employed to optimize Tc via the control of apical oxygen occupancy. For Pr2CuO4+/-δ the resulting square planar coordinated structure exhibits a 25 K superconducting transition in the absence of Cerium doping. Using these films and ultra high magnetic fields (>90 T) enables measurements of magnetic quantum oscillations - the first observation of their kind for a cuprate thin film. The oscillation frequency is consistent with the reconstructed Fermi surface of the bulk electron-doped cuprate Nd2-xCexCuO4. Furthermore, we observe a mass enhancement, suggesting that tuning these materials via oxygen stoichiometry enables exploration of underlying quantum criticality, providing a new axis with which to explore the physics underlying the electron doped side of the cuprate phase diagram.

  15. Electronic excitations in electron-doped cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Unger, P.; Fulde, P.

    1995-04-01

    We calculate the electronic single-particle spectrum of an electron-doped cuprate superconductor such as Nd2-xCexCuO4-y. The dynamics of holes in the Cu-O planes is described by the extended Hubbard or Emery model. We consider the system at half-filling (one hole per unit cell, nh=1) and in the case of electron doping where the ground state is paramagnetic. The projection technique of Mori and Zwanzig is applied to derive the equations of motion for the Green's functions of Cu and O holes. These equations are solved self-consistently as in a previous calculation, where we considered the case of hole doping. At half-filling the system exhibits a charge-transfer gap bounded by Zhang-Rice singlet states and the upper Hubbard band. Upon electron doping the upper Hubbard band crosses the Fermi level and the system becomes metallic. With increasing electron doping the singlet band loses intensity and finally vanishes for nh=0. The corresponding spectral weight is transferred to the upper Hubbard band, which becomes a usual tight-binding band for zero hole concentration. The shape of the flat band crossing the Fermi level fits well to angle-resolved photoemission spectra of Nd2-xCexCuO4-y for x=0.15 and 0.22. Furthermore, our findings are in excellent agreement with exact diagonalization studies of 2×2 CuO2 cluster with periodic boundary conditions.

  16. Theoretical Modeling of Various Spectroscopies for Cuprates and Topological Insulators

    NASA Astrophysics Data System (ADS)

    Basak, Susmita

    Spectroscopies resolved highly in momentum, energy and/or spatial dimensions are playing an important role in unraveling key properties of wide classes of novel materials. However, spectroscopies do not usually provide a direct map of the underlying electronic spectrum, but act as a complex 'filter' to produce a 'mapping' of the underlying energy levels, Fermi surfaces (FSs) and excitation spectra. The connection between the electronic spectrum and the measured spectra is described as a generalized 'matrix element effect'. The nature of the matrix element involved differs greatly between different spectroscopies. For example, in angle-resolved photoemission (ARPES) an incoming photon knocks out an electron from the sample and the energy and momentum of the photoemitted electron is measured. This is quite different from what happens in K-edge resonant inelastic X-ray scattering (RIXS), where an X-ray photon is scattered after inducing electronic transitions near the Fermi energy through an indirect second order process, or in Compton scattering where the incident X-ray photon is scattered inelastically from an electron transferring energy and momentum to the scattering electron. For any given spectroscopy, the matrix element is, in general, a complex function of the phase space of the experiment, e.g. energy/polarization of the incoming photon and the energy/momentum/spin of the photoemitted electron in the case of ARPES. The matrix element can enhance or suppress signals from specific states, or merge signals of groups of states, making a good understanding of the matrix element effects important for not only a robust interpretation of the spectra, but also for ascertaining optimal regions of the experimental phase space for zooming in on states of the greatest interest. In this thesis I discuss a comprehensive scheme for modeling various highly resolved spectroscopies of the cuprates and topological insulators (TIs) where effects of matrix element, crystal

  17. Quantum Phase Transitions of Antiferromagnets and the Cuprate Superconductors

    NASA Astrophysics Data System (ADS)

    Sachdev, Subir

    I begin with a proposed global phase diagram of the cuprate superconductors as a function of carrier concentration, magnetic field, and temperature, and highlight its connection to numerous recent experiments. The phase diagram is then used as a point of departure for a pedagogical review of various quantum phases and phase transitions of insulators, superconductors, and metals. The bond operator method is used to describe the transition of dimerized antiferromagnetic insulators between magnetically ordered states and spin-gap states. The Schwinger boson method is applied to frustrated square lattice antiferromagnets: phase diagrams containing collinear and spirally ordered magnetic states, Z_2 spin liquids, and valence bond solids are presented, and described by an effective gauge theory of spinons. Insights from these theories of insulators are then applied to a variety of symmetry breaking transitions in d-wave superconductors. The latter systems also contain fermionic quasiparticles with a massless Dirac spectrum, and their influence on the order parameter fluctuations and quantum criticality is carefully discussed. I conclude with an introduction to strong coupling problems associated with symmetry breaking transitions in two-dimensional metals, where the order parameter fluctuations couple to a gapless line of fermionic excitations along the Fermi surface.

  18. Infrared pseudogap in cuprate and pnictide high-temperature superconductors

    SciTech Connect

    Moon, S. J.; Lee, Y. S.; Schafgans, A. A.; Chubukov, A. V.; Kasahara, S.; Shibauchi, T.; Terashima, T.; Matsuda, Y.; Tanatar, M. A.; Prozorov, R.; Thaler, A.; Canfield, Paul C.; Bud'ko, Sergey L.; Sefat, A. S.; Mandrus, D.; Segawa, K.; Ando, Y.; Basov, D. N.

    2014-07-01

    We investigate infrared manifestations of the pseudogap in the prototypical cuprate and pnictide superconductors, YBa2Cu3Oy and BaFe2As2 (Ba122) systems. We find remarkable similarities between the spectroscopic features attributable to the pseudogap in these two classes of superconductors. The hallmarks of the pseudogap state in both systems include a weak absorption feature at about 500cm-1 followed by a featureless continuum between 500 and 1500cm-1 in the conductivity data and a significant suppression in the scattering rate below 700–900 cm-1. The latter result allows us to identify the energy scale associated with the pseudogap ΔPG. We find that in the Ba122-based materials the superconductivity-induced changes of the infrared spectra occur in the frequency region below 100–200 cm-1, which is much lower than the energy scale of the pseudogap. We performed theoretical analysis of the scattering rate data of the two compounds using the same model, which accounts for the effects of the pseudogap and electron-boson coupling. We find that the scattering rate suppression in Ba122-based compounds below ΔPG is solely due to the pseudogap formation, whereas the impact of the electron-boson coupling effects is limited to lower frequencies. The magnetic resonance modes used as inputs in our modeling are found to evolve with the development of the pseudogap, suggesting an intimate correlation between the pseudogap and magnetism

  19. Infrared Faraday Measurements on Cuprate High Temperature Superconductors

    NASA Astrophysics Data System (ADS)

    Arik, M. Murat; Mukherjee, Alok; Cerne, John; Lubashevsky, Y.; Pan, Lidong; Armitage, N. P.; Kirzhner, T.; Koren, G.

    2014-03-01

    Recent measurements on cuprate high temperature superconductors (CHTS) have observed evidence for symmetry breakings in the pseudogap phase, suggesting that this is a full-fledged phase with an actual broken symmetry. To test the spectral character of this broken symmetry, we have made infrared polarization-sensitive measurements in the absence of magnetic field on a series of CHTS films. We have studied the Faraday effect (change in the polarization of transmitted light) in CHTS films as a function of temperature (10-300K), energy (0.1-3 eV), and sample orientation with respect to the incident light polarization. We observe a strong linear optical anisotropy, well above the superconducting transition temperature. This signal is maximized when the sample lattice axes are oriented near 45o with respect to the incident light polarization, and varies as the sample is rotated. We explore the temperature and energy dependence of this signal. This work supported by NSF-DMR1006078 and Gordon and Betty Moore Foundation through Grant GBMF2628.

  20. Sun Oven Grown Cuprates Superconductivity and Periodic Lattice Distortions PLD

    NASA Astrophysics Data System (ADS)

    Acrivos, Juana V.; Chidvinadze, J. G.; Gulanova, D. D.; Loy, D.

    2011-03-01

    Bi 1.7 Pb 0.3 Sr 2 Ca n-1 Cu n O4 + 2 n + δ identified by the layer heavy element composition with substitution, s (2 s :2:n-1:n > 2) cuprates grown by green chemistry, transition temperatures to superconductivity Tc = 87 to 150K are related to their structure. Enhanced XRD at energies near but below the Cu K, and Pb and Bi L3-edges for pure n=2, 3 phases show Darwin shaped preferred [HKL] reflections that identify the magnitude of the allowed transition moment from the core state to extended unoccupied states determined by the electron density symmetry in that plane, confirmed by XAS of 3 μ m thick films. Weak PLD are still detected, but the stability gained by substitution of Bi by Pb is the formation of nearly symmetric Pb8 cubes in (2s : 2 : 1 : 2)13 and (2s < formula > < ? TeX super-lattices. The preferred 2D [HKL] reflection planes play the same role in the chemical activity of 3D solids as the linear bonds do in molecular reactions, governed by scattering dependent on the electron density symmetry in their highest and lowest unoccupied states. Supported by US NSF, Dreyfus, DOE Laboratories SSRL-SLAC, STUC-Ukraine and Georgia NSF.

  1. Unraveling electronic and magnetic structure at cuprate-manganite interfaces

    NASA Astrophysics Data System (ADS)

    Freeland, John

    2014-03-01

    Oxide interfaces offer a rich variety of physics and a pathway to create new classes of functional oxide materials. The interface between the cuprate high-temperature superconductors and ferromagnetic manganites is of particular interest due to the strongly antagonistic nature of the superconducting and ferromagnetic phases. Advancements in the synthesis of oxide heterostructure offers the opportunity to merge these two dissimilar oxides with atomic precision to understand the fundamental limits of bringing such states into close proximity. However, the main challenge is to understand the physical framework that describes the behavior of strongly correlated electrons near oxide interfaces. One aspect that will be addressed here is the use of advanced tools to gain detailed electronic and magnetic information from the boundary region. In this talk, recent work will be addressed both in connection to visualizing the interface with spatially resolved tools as well as harnessing layer-by-layer growth to explore the limits in ultrathin superlattices. These insights allow us to better understand the physics behind the interfacial spin and orbital reconstruction observed in this system. Work at Argonne is supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.

  2. Polar Kerr effect in high temperature cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Tewari, Sumanta; Sharma, Girish; Goswami, Pallab; Yakovenko, Victor; Chakravarty, Sudip

    A mechanism is proposed for the tantalizing evidence of polar Kerr effect in a class of high temperature superconductors-the signs of the Kerr angle from two opposite faces of the same sample are identical and magnetic field training is non-existent. The mechanism does not break global time reversal symmetry, as in an antiferromagnet, and results in zero Faraday effect. It is best understood in a phenomenological model of bilayer cuprates, such as YBCO, in which intra-bilayer tunneling nucleates a chiral d-density wave such that the individual layers have opposite chirality. Although the presentation is specific to the chiral d-density wave, the mechanism may be more general to any quasi-two-dimensional orbital antiferromagnet in which time reversal symmetry is broken in each plane, but not when averaged macroscopically. St and GS supported by AFOSR (FA9550-13-1-0045), PG supported by JQI-NSF-PFC, SC supported by NSF-DMR-1004520.

  3. Novel Superoxygenated Phases in Superconducting Cuprate Thin Films

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Zhang, H.; Gauquelin, N.; Botton, G. A.; McMahon, C.; Hawthorn, D. G.; Wei, J. Y. T.

    The superconducting critical temperature (Tc) of hole-doped cuprates tends to increase with their lattice complexity, which is generally correlated with higher states of oxidation. For YBa2Cu3O7 - δ (YBCO-123), it is known that solid-state reaction in high-pressure oxygen can induce the formation of more complex and oxidized phases such as Y2Ba4Cu7O15 - δ (YBCO-247) and Y2Ba4Cu8O16 (YBCO-248). In this work, we apply this superoxygenation concept of material synthesis to nanoscale thin films which, owing to their large surface-to-volume ratio, are more thermodynamically reactive than bulk samples. Epitaxial thin films of YBCO-123 were grown by pulsed laser deposition on (La , Sr) (Al , Ta) O3 substrates, and post-annealed in up to 500 atm of oxygen at 800C. Our post-annealed films show robust superconducting transitions with Tc ranging from 80 to 93K. Transmission electron microscopy and X-ray absorption spectroscopy were used to probe the lattice structure and oxygen stoichiometry. Our measurements show clear evidence of conversion to YBCO-247 and YBCO-248 in the superoxygenated films, as well as YBCO-125, a novel YBCO phase that has three CuO chains per unit cell and potentially higher Tc. Work supported by NSERC, CFI/OIT, and CIFAR.

  4. High Temperature Electrical Properties and Defect Structures of Alkaline Earth-Doped Lanthanum Cuprate Superconductors.

    NASA Astrophysics Data System (ADS)

    Shen, Li.

    1995-01-01

    Existing oxygen nonstoichiometry data of rm La_{2-x}Ba_{x}CuO _{4-y} and rm La _{2-x}Sr_{x}CuO_ {4-y} have been fitted by defect structure models featuring isolated oxygen vacancies, neutral associates and singly charged associates, respectively. The associate models fit the data acceptably well up to x = 0.4 while the isolated vacancy model does not fit the data as satisfactorily. Therefore, the oxygen deficiency in both systems is attributed to dopant-vacancy associates rather than isolated oxygen vacancies. However, all three models are unable to reproduce the flattening of electrical properties at high doping levels. Jonker plots reveal that the flattening is caused by degeneracy. The oxygen partial pressure dependence of the electrical properties indicates that the associates are not neutral but singly charged. Thermoelectric power and electrical conductivity have been measured in situ for rm La_ {2-x}Ca_{x}CuO_{4 -y} with x = 0-0.16 in P(O_2 ) = 10^{-5} { -1} atm at T = 700-1000^circ C. The results are similar to those of rm La_{2-x}Ba_{x}CuO _{4-y} and rm La _{2-x}Sr_{x}CuO_ {4-y} yet significant magnitudes of oxygen deficiency reportedly occur in rm La_ {2-x}Ca_{x}CuO_{4 -y} at much lower doping levels. Defect structure models involving charged oxygen vacancies cannot simultaneously fit both properties. Neutral oxygen vacancies and their association with dopants were invoked to reconcile both electrical property and oxygen nonstoichiometry data. The proposed defect structure models have been rationalized based on the bond-length mismatch first observed by Goodenough and his coworkers. The Cu-O bonds in the CuO_2 layers are longer than the La-O bonds in the (LaO)_2 layers. Substitution of larger Ba or Sr for La relieves the mismatch by lengthening the La-O bonds. Holes created for charge compensation contribute to the relief by shortening the Cu-O bonds. Once the mismatch is completely relieved, charged oxygen vacancies are formed in the (LaO)_2 layers, to minimize further expansions. The electrostatic attraction leads to the association of oppositely charged dopants and vacancies. Substitution of smaller Ca for La aggravates the mismatch by further shortening the La-O bonds. Neutral oxygen vacancies, together with holes, form in the CuO _2 layers to shorten Cu-O bonds to compensate the shortening of the La-O bonds. The association of dopants and vacancies can be explained by the preference of Ca for eight-fold coordination.

  5. Interpretation of scanning tunneling quasiparticle interference and impurity states in cuprates.

    PubMed

    Kreisel, A; Choubey, Peayush; Berlijn, T; Ku, W; Andersen, B M; Hirschfeld, P J

    2015-05-29

    We apply a recently developed method combining first principles based Wannier functions with solutions to the Bogoliubov-de Gennes equations to the problem of interpreting STM data in cuprate superconductors. We show that the observed images of Zn on the surface of Bi_{2}Sr_{2}CaCu_{2}O_{8} can only be understood by accounting for the tails of the Cu Wannier functions, which include significant weight on apical O sites in neighboring unit cells. This calculation thus puts earlier crude "filter" theories on a microscopic foundation and solves a long-standing puzzle. We then study quasiparticle interference phenomena induced by out-of-plane weak potential scatterers, and show how patterns long observed in cuprates can be understood in terms of the interference of Wannier functions above the surface. Our results show excellent agreement with experiment and enable a better understanding of novel phenomena in the cuprates via STM imaging. PMID:26066452

  6. Infrared conductivity of cuprates using Yang-Rice-Zhang ansatz: Review of our recent investigations

    SciTech Connect

    Singh, Navinder; Sharma, Raman

    2015-05-15

    A review of our recent investigations related to the ac transport properties in the psedogapped state of cuprate high temperature superconductors is presented. For our theoretical calculations we use a phenomenological Green’s function proposed by Yang, Rice and Zhang (YRZ). This is based upon the renormalized mean-field theory of the Hubbard model and takes into account the strong electron-electron interaction present in Cuprates. The pseudogap is also taken into account through a proposed self energy. We have tested the form of the Green’s function by computing ac conductivity of cuprates and then compared with experimental results. We found agreement between theory and experiment in reproducing the doping evolution of ac conductivity but there is a problem with absolute magnitudes and their frequency dependence. This shows a partial success of the YRZ ansatz. The ways to rectify it are suggested and worked out.

  7. Itinerant effects and enhanced magnetic interactions in Bi-based multilayer cuprates

    SciTech Connect

    Dean, M. P. M.; James, A. J. A.; Walters, A. C.; Bisogni, V.; Jarrige, I.; Hücker, M.; Giannini, E.; Fujita, M.; Pelliciari, J.; Huang, Y. B.; Konik, R. M.; Schmitt, T.; Hill, J. P.

    2014-12-04

    The cuprate high temperature superconductors exhibit a pronounced trend in which the superconducting transition temperature, T c, increases with the number of CuO₂ planes, n, in the crystal structure. We compare the magnetic excitation spectrum of Bi₂₊xSr₂₋xCuO₆+δ (Bi-2201) and Bi₂Sr₂Ca₂Cu₃O₁₀₊δ (Bi-2223), with n = 1 and n = 3 respectively, using Cu L₃-edge resonant inelastic x-ray scattering (RIXS). Near the anti-nodal zone boundary we find the paramagnon energy in Bi-2223 is substantially higher than that in Bi-2201, indicating that multilayer cuprates host stronger effective magnetic exchange interactions, providing a possible explanation for the Tc vs. n scaling. In contrast, the nodal direction exhibits very strongly damped, almost non-dispersive excitations. As a result, we argue that this implies that the magnetism in the doped cuprates is partially itinerant in nature.

  8. Transport anomalies and quantum criticality in electron-doped cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Zhang, Xu; Yu, Heshan; He, Ge; Hu, Wei; Yuan, Jie; Zhu, Beiyi; Jin, Kui

    2016-06-01

    Superconductivity research is like running a marathon. Three decades after the discovery of high-Tc cuprates, there have been mass data generated from transport measurements, which bring fruitful information. In this review, we give a brief summary of the intriguing phenomena reported in electron-doped cuprates from the aspect of electrical transport as well as the complementary thermal transport. We attempt to sort out common features of the electron-doped family, e.g. the strange metal, negative magnetoresistance, multiple sign reversals of Hall in mixed state, abnormal Nernst signal, complex quantum criticality. Most of them have been challenging the existing theories, nevertheless, a unified diagram certainly helps to approach the nature of electron-doped cuprates.

  9. Strain-controlled critical temperature in REBa2Cu3Oy-coated conductors

    PubMed Central

    Awaji, Satoshi; Suzuki, Takumi; Oguro, Hidetoshi; Watanabe, Kazuo; Matsumoto, Kaname

    2015-01-01

    Recently, we succeeded in detwinning REBa2Cu3O7 (RE123, RE = rare-earth elements)-coated conductors by annealing under an external uniaxial strain. Using the untwinned RE123 tapes, the uniaxial-strain dependencies of the critical temperature Tc along the a and b crystal axes were investigated over a wide strain region from compression to tension. We found that the strain dependencies of Tc for the a and b axes obey a power law but exhibit opposite slopes. In particular, the maximum value of Tc is obtained when the CuO2 plane becomes a square, and its lattice constant is close to 0.385 nm. It is suggested that a tetragonal structure with a ≈ 0.385 nm is the optimum condition for a high critical temperature in high-Tc cuprates. PMID:26063123

  10. Strain-controlled critical temperature in REBa2Cu3Oy-coated conductors.

    PubMed

    Awaji, Satoshi; Suzuki, Takumi; Oguro, Hidetoshi; Watanabe, Kazuo; Matsumoto, Kaname

    2015-01-01

    Recently, we succeeded in detwinning REBa2Cu3O7 (RE123, RE = rare-earth elements)-coated conductors by annealing under an external uniaxial strain. Using the untwinned RE123 tapes, the uniaxial-strain dependencies of the critical temperature Tc along the a and b crystal axes were investigated over a wide strain region from compression to tension. We found that the strain dependencies of Tc for the a and b axes obey a power law but exhibit opposite slopes. In particular, the maximum value of Tc is obtained when the CuO2 plane becomes a square, and its lattice constant is close to 0.385 nm. It is suggested that a tetragonal structure with a ≈ 0.385 nm is the optimum condition for a high critical temperature in high-Tc cuprates. PMID:26063123

  11. Doping-dependent charge order correlations in electron-doped cuprates.

    PubMed

    da Silva Neto, Eduardo H; Yu, Biqiong; Minola, Matteo; Sutarto, Ronny; Schierle, Enrico; Boschini, Fabio; Zonno, Marta; Bluschke, Martin; Higgins, Joshua; Li, Yangmu; Yu, Guichuan; Weschke, Eugen; He, Feizhou; Le Tacon, Mathieu; Greene, Richard L; Greven, Martin; Sawatzky, George A; Keimer, Bernhard; Damascelli, Andrea

    2016-08-01

    Understanding the interplay between charge order (CO) and other phenomena (for example, pseudogap, antiferromagnetism, and superconductivity) is one of the central questions in the cuprate high-temperature superconductors. The discovery that similar forms of CO exist in both hole- and electron-doped cuprates opened a path to determine what subset of the CO phenomenology is universal to all the cuprates. We use resonant x-ray scattering to measure the CO correlations in electron-doped cuprates (La2-x Ce x CuO4 and Nd2-x Ce x CuO4) and their relationship to antiferromagnetism, pseudogap, and superconductivity. Detailed measurements of Nd2-x Ce x CuO4 show that CO is present in the x = 0.059 to 0.166 range and that its doping-dependent wave vector is consistent with the separation between straight segments of the Fermi surface. The CO onset temperature is highest between x = 0.106 and 0.166 but decreases at lower doping levels, indicating that it is not tied to the appearance of antiferromagnetic correlations or the pseudogap. Near optimal doping, where the CO wave vector is also consistent with a previously observed phonon anomaly, measurements of the CO below and above the superconducting transition temperature, or in a magnetic field, show that the CO is insensitive to superconductivity. Overall, these findings indicate that, although verified in the electron-doped cuprates, material-dependent details determine whether the CO correlations acquire sufficient strength to compete for the ground state of the cuprates. PMID:27536726

  12. Doping-dependent charge order correlations in electron-doped cuprates

    PubMed Central

    da Silva Neto, Eduardo H.; Yu, Biqiong; Minola, Matteo; Sutarto, Ronny; Schierle, Enrico; Boschini, Fabio; Zonno, Marta; Bluschke, Martin; Higgins, Joshua; Li, Yangmu; Yu, Guichuan; Weschke, Eugen; He, Feizhou; Le Tacon, Mathieu; Greene, Richard L.; Greven, Martin; Sawatzky, George A.; Keimer, Bernhard; Damascelli, Andrea

    2016-01-01

    Understanding the interplay between charge order (CO) and other phenomena (for example, pseudogap, antiferromagnetism, and superconductivity) is one of the central questions in the cuprate high-temperature superconductors. The discovery that similar forms of CO exist in both hole- and electron-doped cuprates opened a path to determine what subset of the CO phenomenology is universal to all the cuprates. We use resonant x-ray scattering to measure the CO correlations in electron-doped cuprates (La2−xCexCuO4 and Nd2−xCexCuO4) and their relationship to antiferromagnetism, pseudogap, and superconductivity. Detailed measurements of Nd2−xCexCuO4 show that CO is present in the x = 0.059 to 0.166 range and that its doping-dependent wave vector is consistent with the separation between straight segments of the Fermi surface. The CO onset temperature is highest between x = 0.106 and 0.166 but decreases at lower doping levels, indicating that it is not tied to the appearance of antiferromagnetic correlations or the pseudogap. Near optimal doping, where the CO wave vector is also consistent with a previously observed phonon anomaly, measurements of the CO below and above the superconducting transition temperature, or in a magnetic field, show that the CO is insensitive to superconductivity. Overall, these findings indicate that, although verified in the electron-doped cuprates, material-dependent details determine whether the CO correlations acquire sufficient strength to compete for the ground state of the cuprates. PMID:27536726

  13. Diamagnetism of real-space pairs above T(c) in hole doped cuprates.

    PubMed

    Alexandrov, A S

    2010-10-27

    The nonlinear normal state diamagnetism reported by Li et al (2010 Phys. Rev. B 81 054510) is shown to be incompatible with a claimed Cooper pairing and vortex liquid above the resistive critical temperature. However, it is perfectly compatible with the normal state Landau diamagnetism of real-space composed bosons, which provides a description of the nonlinear magnetization curves of the less anisotropic cuprates La-Sr-Cu-O (LSCO) and Y-Ba-Cu-O (YBCO) as well as for strongly anisotropic bismuth-based cuprates over the whole range of available magnetic fields. PMID:21403318

  14. Tuning order in the cuprate superconductors by a magnetic field

    NASA Astrophysics Data System (ADS)

    Sachdev, Subir

    2002-03-01

    An innovative series of recent neutron scattering(B. Lake et al.), Science 291, 1759 (2001); B. Khyakovich et al., preprint; B. Lake et al., preprint. and STM(J. Hoffman et al.), Science, Feb 2002. experiments have shed new light on the nature of strong correlations in the cuprate superconductors. Some of these experiments use a magnetic field, applied perpendicular to the CuO2 layers, to tune the low temperature properties of the superconducting state. Their results support the idea that ground state correlations in the doped Mott insulator can be described using a framework of competing order parameters, and of proximity to quantum phase transitions associated with them. In our view, they also offer compelling evidence that the orders competing with superconductivity are spin and charge density waves. The predictions(E. Demler, S. Sachdev, and Y. Zhang, Phys. Rev. Lett. 87), 067202 (2001); S. Sachdev, cond- mat/0108238 A. Polkovnikov, S. Sachdev, M. Vojta, and E. Demler, cond- mat/0110329. of the theories of such quantum transitions will be reviewed and compared with the recent experimental results. In particular, we show that the quantum theory of a spin-density-wave ordering transition in a superconductor simultaneously describes a variety of observations with a single set of typical parameters: the field dependence of the elastic neutron scattering intensity, the absence of satellite Bragg peaks associated with the vortex lattice in existing neutron scattering experiments, and the spatial extent of the charge order in STM experiments.

  15. Interlayer coupling and the thermopower of cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Zhou, J.-S.; Goodenough, J. B.

    1996-11-01

    A review of the extant literature on the thermopower (TEP) of the cuprate superconductors reveals a transition from polaronic to homogeneous itinerant electron behavior with increasing hole concentration in the CuO2 sheets. Superconductivity appears at the compositions of crossover from one regime to the other, and the normal state of the superconductors retains a heterogeneous electronic structure of mobile hole-rich and hole-poor domains, which introduces both a statistical and a transport component to the Seebeck coefficient. A primary manifestation of the transport component is an enhancement term δα(T) having a maximum at a Tmax=100-140 K, which is characteristic of a strong coupling of the charge carriers to optical rather than acoustic phonons. Comparison of the TEP for La1.85Sr0.15CuO4 vs La0.85Sr1.15GaCuO5 and La1.8Sr0.2CaCu2O6+δ vs Bi2Sr2CaCu2O8+δ indicates that an increase in the c-axis coupling between neighboring CuO2 sheets increases the size of the polaron or hole-rich domains in the underdoped compositions, thereby lowering the room-temperature value of the Seebeck coefficient α(300 K) and increasing the magnitude of δα(T). These observations implicate a strong elastic component, enhanced by electron-lattice interactions, in the c-axis coupling as well as in the formation of larger nonadiabatic polarons and their interactions within the CuO2 planes. They also signal that caution must be exercised in any application of a ``universal plot'' of α(300 K) versus hole concentration p per Cu atom in a CuO2 plane to obtain a value of p from TEP data.

  16. Angle-Resolved Photoemission Spectroscopy on Electronic Structure and Electron-Phonon Coupling in Cuprate Superconductors

    SciTech Connect

    Zhou, X.J.

    2010-04-30

    In addition to the record high superconducting transition temperature (T{sub c}), high temperature cuprate superconductors are characterized by their unusual superconducting properties below T{sub c}, and anomalous normal state properties above T{sub c}. In the superconducting state, although it has long been realized that superconductivity still involves Cooper pairs, as in the traditional BCS theory, the experimentally determined d-wave pairing is different from the usual s-wave pairing found in conventional superconductors. The identification of the pairing mechanism in cuprate superconductors remains an outstanding issue. The normal state properties, particularly in the underdoped region, have been found to be at odd with conventional metals which is usually described by Fermi liquid theory; instead, the normal state at optimal doping fits better with the marginal Fermi liquid phenomenology. Most notable is the observation of the pseudogap state in the underdoped region above T{sub c}. As in other strongly correlated electrons systems, these unusual properties stem from the interplay between electronic, magnetic, lattice and orbital degrees of freedom. Understanding the microscopic process involved in these materials and the interaction of electrons with other entities is essential to understand the mechanism of high temperature superconductivity. Since the discovery of high-T{sub c} superconductivity in cuprates, angle-resolved photoemission spectroscopy (ARPES) has provided key experimental insights in revealing the electronic structure of high temperature superconductors. These include, among others, the earliest identification of dispersion and a large Fermi surface, an anisotropic superconducting gap suggestive of a d-wave order parameter, and an observation of the pseudogap in underdoped samples. In the mean time, this technique itself has experienced a dramatic improvement in its energy and momentum resolutions, leading to a series of new discoveries not

  17. Neutron scattering studies on stripe phases in non-cuprate materials

    NASA Astrophysics Data System (ADS)

    Ulbrich, Holger; Braden, Markus

    2012-11-01

    Several non-cuprates layered transition-metal oxides exhibit clear evidence for stripe ordering of charges and magnetic moments. Therefore, stripe order should be considered as the typical consequence of doping a layered Mott insulator, but only in cuprates stripe order or fluctuating stripes coexist with metallic properties. A linear relationship between the charge concentration and the incommensurate structural and magnetic modulations can be considered as the finger print of stripe ordering with localized degrees of freedom. In nickelates and in cobaltates with K2NiF4 structure, doping suppresses the nearest-neighbor antiferromagnetism and induces stripe order. The higher amount of doping needed to induce stripe phases in these non-cuprates series can be attributed to reduced charge mobility. Also manganites exhibit clear evidence for stripe phases with further enhanced complexity, because orbital degrees of freedom are involved. Orbital ordering is the key element of stripe order in manganites since it is associated with the strongest structural distortion and with the perfectly fulfilled relation between doping and incommensurability. Magnetic excitations in insulating stripe phases exhibit strong similarity with those in the cuprates, but only for sufficiently short magnetic correlation lengths reflecting well-defined magnetic stripes that are only loosely coupled.

  18. Origin of dz2 orbital suppression of d-wave superconductive pairs in cuprate

    NASA Astrophysics Data System (ADS)

    Tang, Huai Bao; Li, Guang; Zhang, Hai Jun; Zuo, Xue Qin; Meng, Fan Ming; Liu, Da Yong

    2015-07-01

    Compared to Hg-cuprate, the origin that the dz2 orbital suppresses the d-wave superconductive (SC) pairs in La-cuprate is studied based on an effective two-orbital t-J-U model by using the Kotliar-Ruckenstein (KR) slave-boson technique. By analyzing the orbital-dependent electron distribution, it is elaborated that the double occupancy of dx2-y2 orbital, caused by the dz2 orbital mixture, should be responsible for the suppression of the d-wave SC pairs in La-cuprate. When the Coulomb interaction U increases, the ground state hosting the large double occupancy of dx2-y2 orbital in La-cuprate is stabilized by the localization of the carriers due to the Coulomb-blocking instead of reducing the double occupancy by the way of lowering of Coulomb potential energy. Therefore, it could be concluded that the mechanism that the double occupancy destructs against d-wave SC pairs is robust even if the strong Coulomb interaction exists in the La-based compounds.

  19. Quantized massive collective modes and massive spin fluctuations in high-Tc cuprates

    NASA Astrophysics Data System (ADS)

    Kanazawa, I.; Sasaki, T.

    2015-10-01

    We have analyzed angle-resolved photoemission spectra of the single- and double-layered Bi-family high-Tc superconductors by using quantized massive gauge fields, which might contain effects of spin fluctuations, charge fluctuations, and phonons. It is suggested strongly that the quantized massive gauge fields might be mediating Cooper pairing in high-Tc cuprates.

  20. Spin excitations and superconductivity in cuprate oxide and heavy electron superconductors

    NASA Astrophysics Data System (ADS)

    Pines, David

    1990-04-01

    The experimental evidence for a temperature-dependent build up of antiferromagnetic correlations between Cu 2+ planar spins in the normal state of cuprate oxide superconductors is reviewed, and a phenomenological one-component model, developed in collaboration with A. Millis and H. Monien, which appears capable of providing a quantitative account of existing experiments is described. A scaling law which relates the superconducting transaction temperature to the measurable spin-spin correlation length is proposed. The NMR experimental results in the superconducting state are shown to be consistent with d-wave pairing in a strong coupling superconductor. Comparison of the results of NMR experiments on the cuprate oxide and heavy electron superconductors reveals striking similarities. I conclude that the cuprate oxide superconductors are unconventional superconductors in which the superconductivity is of (primarily) electronic origin and results from an attractive interaction of antiferromagnetic character between itinerant quasiparticles in the spin antisymmetric channel, and discuss similarities and differences between cuprate oxide and heavy electron systems.

  1. Excitation of coherent oscillations in underdoped cuprate superconductors by intense THz pulses

    NASA Astrophysics Data System (ADS)

    Hoffmann, Matthias C.; Lee, Wei-Sheng; Dakovski, Georgi L.; Turner, Joshua J.; Gerber, Simon M.; Bonn, Doug; Hardy, Walter; Liang, Ruixing; Salluzzo, Marco

    2016-05-01

    We use intense broadband THz pulses to excite the cuprate superconductors YBCO and NBCO in their underdoped phase, where superconducting and charge density wave ground states compete. We observe pronounced coherent oscillations at attributed to renormalized low-energy phonon modes. These oscillation features are much more prominent than those observed in all-optical pump-probe measurements, suggesting a different excitation mechanism.

  2. Nuclear Magnetic Resonance and High-Temperature Superconductivity in YTTRIUM(1-X)PRASEODYMIUM(X)BARIUM Cuprate

    NASA Astrophysics Data System (ADS)

    Reyes, Arneil Payongayong

    Copper nuclear magnetic resonance (NMR) has been performed on praseodymium-doped YBa_2Cu _3O_7, to investigate the nature of the depression of the superconducting transition temperature T_{c} with Pr concentration in this series and to provide insight into the microscopic and magnetic properties of high T_{c } planar cuprate materials. Praseodymium is unique among rare-earth dopants in suppressing superconductivity in the high T _{c} cuprate YBa _2Cu_3O_7 while maintaining the orthorhombic structure of the host. Temperature dependence of the Knight shift K and the nuclear relaxation rate 1/T_1 has been observed in Y-rich Y_{1-x}Pr _ xBa_2Cu _3O_7. Its striking resemblance to the behavior found in oxygen deficient YBa_2Cu_3O _{7-y} provides evidence that T_{c} depression in the former is primarily due to the removal of hole carriers as a consequence of Pr being close to tetravalent state. This hole-filling mechanism is consistent with the observed antiferromagnetic ordering of Cu spins on the plane sites in both PrBa_2Cu_3O_7 and YBa_2Cu_3O_6 since the absence of the doped-holes on the Cu -O_2 planes enhances spin correlations among Cu local moments. On the other hand, extensive analysis of the spin susceptibility has shown a tendency towards trivalency of Pr in specimens with low x values, suggesting that in the dilute limit pair-breaking due to conduction band-4f hybridization is also involved in the depression of T_{c}. The mixed-valent nature of Pr must therefore be considered for any adequate explanation of the suppression of superconductivity in Y_{1-x}Pr_ xBa_2Cu_3 O_7. The phenomenological model of antiferromagnetic Fermi liquid (AFL) proposed by Millis, Monien and Pines has been used to explain the behavior of the planar ^{63}Cu relaxation rate and to extract information on the strength of correlations among the local spins. Analysis has shown that the unusual behavior of the relaxation rate is a consequence of a competition between the temperature

  3. Optical Properties of Doped Cuprates and Related Materials

    NASA Astrophysics Data System (ADS)

    Yoon, Young-Duck

    1995-01-01

    The optical properties of cuprates, rm Nd_{2-it x}Ce_{it x}CuO_4 and rm La_ {2-it x}Sr_{it x}CuO _4, and the related materials, rm Ba_{1-it x}K_{it x}BiO_3 (BKBO) and rm BaPb_{1-it x}Bi_{1- it x}O_3 (BPBO), have been extensively investigated by doping- and temperature-dependent reflectance measurement of single crystal samples in the frequency range between 30 cm^{-1} (4 meV) and 40 000 cm^{-1} (5 eV). The rm Nd_{2-it x}Ce_{it x}CuO_4 system has been studied at Ce compositions in the range 0 <=q x <=q 0.2. rm La_{2-it x}Sr_{it x}CuO_4 has been studied in the spin glass doping regime, (x <=q 0.04). The two bismuthates have been investigated as superconducting materials with the maximum T_{c} . Our results for rm Nd_{2 -it x}Ce_{it x}CuO_4 show that doping with electrons induces a transfer of spectral weight from the high energy side above the charge transfer excitation band to the low energy side below 1.2 eV, similar to the results observed in hole-doped rm La_{2-it x}Sr_ {it x}CuO_4. However, the low frequency spectral weight grows slightly faster than 2x with doping x, as expected for the Mott-Hubbard model. We find very interesting results at low doping levels in rm La_{2-it x }Sr_{it x}CuO_4. Upon Sr doping the oscillator strength of the phonons is gradually reduced and doping induced modes (Raman modes and carrier-lattice interaction mode) appear in the far -infrared. We also find that the deformation potential by the dynamical tilting of CuO_6 octahedra induces a carrier-lattice interaction. The carrier -lattice interaction is characterized by strong infrared active modes and an appearance of the strong A _{g} Raman modes upon cooling. Finally, we present the normal and the superconducting properties of Bi-O superconductors. We conclude that the BKBO system is a weak- or moderate-coupling BCS-type superconductor in the dirty limit.

  4. Microwave Absorption and Low-Frequency AC Losses in 1-2-3 Cuprate Superconductors

    NASA Astrophysics Data System (ADS)

    Huang, Ming Xun

    We have studied various aspects of microwave absorption in cuprates of the prototype REBa_2Cu _3O_{rm x} (6 < x < 7), where RE stands for Y or a rare earth ion. The first series of experiments concern the discovery and subsequent elucidation of a huge increase in zero field microwave absorption, at temperatures below 20 K, in micron size powder samples of ErBa_2Cu _3O_{rm x}. The field dependence of the microwave absorption was used to show that this abnormal zero field signal is a part of a broad and highly distorted electron spin resonance (ESR) spectrum. Spectra at different frequencies were analyzed using the "weak exchange, strong dipole field" Kubo-Toyabe model for the first time and we conclude that there is a large (~1 kOe) fluctuating local dipolar field at the Er site coming from the other Er^{3+} magnetic moments. For better understanding, experiments were done on ESR in powders of Er_{rm x}Y _{rm 1-z}Ba_2 Cu_3O_6 (0.02 < z < 1). For z < 0.4, another partially resolved line appeared at low fields. These spectra cannot be described as a powder pattern due to a single line with an anisotropic g-value. Rather they appear to be the sum of two Kubo -Toyabe lines. Most likely these lines are resonances coming from two closely spaced (~1K) low lying doublets. Crystal field calculations indicate that the distortion away from cubic symmetry implied by our results is much smaller than that required to describe the results of neutron scattering measurements. Another series of experiments were done to measure the increase in the microwave absorption in thin films of YBa_2Cu_3O _7 due to the application of a dc magnetic field (B) between 0.45 and 1.4 Tesla at 0.8 < (T/Tc) < 1. The data are very well represented by conventional models of fluxon dynamics. We have also measured the real (chi _1) and imaginary (chi_2 ) parts of the low frequency (<150 Hz) complex ac susceptibility. It was found that the data can be understood by using the Bean model.

  5. Evolution of superconducting gap and metallic ground state in cuprates from transport

    NASA Astrophysics Data System (ADS)

    Taillefer, Louis

    2006-03-01

    We report on fundamental characteristics of the ground state of cuprates in the limit of T=0, for both normal and superconducting states, obtained from transport measurements on high-quality single crystals of YBCO and Tl-2201, as a function of hole concentration. The superconducting gap is extracted from thermal conductivity; it is found to scale with the superconducting transition temperature throughout the overdoped regime, with a gap-to-Tc ratio of 5 [1]. The normal state is accessed by suppressing superconductivity with magnetic fields up to 60 T and is characterized by the limiting behavior of its electrical resistivity; while carrier localization is observed in YBCO at low temperature for carrier concentrations p below 0.1 hole/planar Cu, at p=0.1 and above the material remains highly metallic down to T=0 [2]. This shows that the non-superconducting state of underdoped cuprates, deep in the pseudogap phase, is remarkably similar to that of strongly overdoped cuprates, e.g. at p=0.3. We compare these results with similar measurements on other cuprates and discuss their implication for our understanding of the cuprate phase diagram. [1] In collaboration with: D.G. Hawthorn, S.Y. Li, M. Sutherland, E. Boaknin, R.W. Hill, C. Proust, F. Ronning, M. Tanatar, J. Paglione, D. Peets, R. Liang, D.A. Bonn, W.N. Hardy, and N.N. Kolesnikov. [2] In collaboration with: C. Proust, M. Sutherland, N. Doiron- Leyraud, S.Y. Li, R. Liang, D.A. Bonn, W.N. Hardy, N.E. Hussey, S. Adachi, S. Tajima, J. Levallois, and M. Narbone.

  6. Atomic scale studies of doped-hole distributions, self-organized electronic nano-domains, and electron-boson coupling in high Tc-cuprates

    SciTech Connect

    Davis, James C.

    2014-05-14

    Progress is reported in these areas (titles and abstracts of journal articles produced for the contract): Exotic Density Wave in Underdoped Cuprates; Varying the inter-atomic distances within individual crystal unit-­cells of cuprates; Truncated Momentum Space Electronic Structure of Underdoped Bi2Sr2CaCu2O8+δ; and, Visualizing Phase Fluctuating d-Wave Superconductivity in the Cuprate Pseudogap State.

  7. Variable-range hopping theory for the gap observed in strongly underdoped cuprate Bi2Sr2 -xLaxCuO6 +δ

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Qiang; Zhang, Jun-Qiu; Rice, T. M.; Zhang, Fu-Chun

    2016-06-01

    Recent angle resolved photoemission spectroscopy experiments on strongly underdoped Bi2Sr2 -xLaxCuO6 +δ cuprates have reported an unusual gap in the nodal direction. Transport experiments on these cuprates observed variable-range hopping behavior. These cuprates have both electron and hole doping, which has led to proposals that this cuprate is analogous to partially compensated semiconductors. The nodal gap then corresponds to the Efros-Shklovskii (ES) gap in such semiconductors. We calculate the doping and temperature dependence of an ES gap model and find support for an Efros-Shklovskii model.

  8. Two-dimensional superconductor-insulator quantum phase transitions in an electron-doped cuprate

    NASA Astrophysics Data System (ADS)

    Zeng, S. W.; Huang, Z.; Lv, W. M.; Bao, N. N.; Gopinadhan, K.; Jian, L. K.; Herng, T. S.; Liu, Z. Q.; Zhao, Y. L.; Li, C. J.; Harsan Ma, H. J.; Yang, P.; Ding, J.; Venkatesan, T.; Ariando

    2015-07-01

    We use an ionic liquid-assisted electric-field effect to tune the carrier density in an electron-doped cuprate ultrathin film and cause a two-dimensional superconductor-insulator transition (SIT). The low upper critical field in this system allows us to perform magnetic-field (B)-induced SIT in the liquid-gated superconducting film. Finite-size scaling analysis indicates that SITs induced both by electric and by magnetic fields are quantum phase transitions and the transitions are governed by percolation effects—quantum mechanical in the former and classical in the latter cases. Compared to the hole-doped cuprates, the SITs in the electron-doped system occur at critical sheet resistances (Rc) much lower than the pair quantum resistance RQ=h /(2e ) 2=6.45 k Ω , suggesting the possible existence of fermionic excitations at finite temperatures at the insulating phase near the SITs.

  9. Strong coupling critique of spin fluctuation driven charge order in underdoped cuprates

    NASA Astrophysics Data System (ADS)

    Mishra, Vivek; Norman, M. R.

    2015-08-01

    Charge order has emerged as a generic feature of doped cuprates, leading to important questions about its origin and its relation to superconductivity. Recent experiments on two classes of hole doped cuprates indicate a novel d -wave symmetry for the order. These were motivated by earlier spin fluctuation theoretical studies based on an expansion about hot spots in the Brillouin zone that indicated such an order would be competitive with d -wave superconductivity. Here, we reexamine this problem by solving strong coupling equations in the full Brillouin zone for experimentally relevant parameters. We find that bond-oriented order, as seen experimentally, is strongly suppressed. We also include coupling to B1 g phonons and do not see any qualitative change. Our results argue against an itinerant model for the charge order, implying instead that such order is likely due to Coulombic phase separation of the doped holes.

  10. Wiedemann-Franz law in the underdoped cuprate superconductor YBa2Cu3Oy

    NASA Astrophysics Data System (ADS)

    Grissonnanche, G.; Laliberté, F.; Dufour-Beauséjour, S.; Matusiak, M.; Badoux, S.; Tafti, F. F.; Michon, B.; Riopel, A.; Cyr-Choinière, O.; Baglo, J. C.; Ramshaw, B. J.; Liang, R.; Bonn, D. A.; Hardy, W. N.; Krämer, S.; LeBoeuf, D.; Graf, D.; Doiron-Leyraud, N.; Taillefer, Louis

    2016-02-01

    The electrical and thermal Hall conductivities of the cuprate superconductor YBa2Cu3Oy , σx y and κx y, were measured in a magnetic field up to 35 T, at a hole concentration (doping) p =0.11 . In the T =0 limit, we find that the Wiedemann-Franz law, κx y/T =(π2/3 ) (kB/e ) 2σx y , is satisfied for fields immediately above the vortex-melting field Hvs. This rules out the existence of a vortex liquid at T =0 and it puts a clear constraint on the nature of the normal state in underdoped cuprates, in a region of the doping phase diagram where charge-density-wave order is known to exist. As the temperature is raised, the Lorenz ratio, Lxy=κxy/(σxyT ) , decreases rapidly, indicating that strong small-q scattering processes are involved.

  11. TOPICAL REVIEW: Theory of extrinsic and intrinsic tunnelling in cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Beanland, J.; Alexandrov, A. S.

    2010-10-01

    There has been a huge theoretical and experimental push to try to illuminate the mechanism behind the high-temperature superconductivity of copper oxides. Cuprates are distinguishable from conventional metallic superconductors in originating from the doping of the parent charge-transfer insulators. The superconducting parts are weakly coupled two-dimensional doped layers held together by the parent lattice. Apart from their high-Tc they have other characteristic features including the 'superconducting' gap (SG) which develops below the superconducting critical temperature and can be seen in extrinsic and intrinsic tunnelling experiments as well as using high-resolution angle-resolved photoemission (ARPES); there also exists another energy gap, the 'pseudogap' (PG), which is a large anomalous gap that exists well above Tc. We present a brief review of recent theories behind the pseudogap and discuss in detail one specific (polaronic) approach which explains the SG, PG and unusual tunnelling characteristics of cuprate superconductors.

  12. Perspective on the phase diagram of cuprate high-temperature superconductors

    NASA Astrophysics Data System (ADS)

    Rybicki, Damian; Jurkutat, Michael; Reichardt, Steven; Kapusta, Czesław; Haase, Jürgen

    2016-05-01

    Universal scaling laws can guide the understanding of new phenomena, and for cuprate high-temperature superconductivity the influential Uemura relation showed, early on, that the maximum critical temperature of superconductivity correlates with the density of the superfluid measured at low temperatures. Here we show that the charge content of the bonding orbitals of copper and oxygen in the ubiquitous CuO2 plane, measured with nuclear magnetic resonance, reproduces this scaling. The charge transfer of the nominal copper hole to planar oxygen sets the maximum critical temperature. A three-dimensional phase diagram in terms of the charge content at copper as well as oxygen is introduced, which has the different cuprate families sorted with respect to their maximum critical temperature. We suggest that the critical temperature could be raised substantially if one were able to synthesize materials that lead to an increased planar oxygen hole content at the expense of that of planar copper.

  13. Electronic structure of cuprate superconductors in a full charge-spin recombination scheme

    NASA Astrophysics Data System (ADS)

    Feng, Shiping; Kuang, Lülin; Zhao, Huaisong

    2015-10-01

    A long-standing unsolved problem is how a microscopic theory of superconductivity in cuprate superconductors based on the charge-spin separation can produce a large electron Fermi surface. Within the framework of the kinetic-energy driven superconducting mechanism, a full charge-spin recombination scheme is developed to fully recombine a charge carrier and a localized spin into a electron, and then is employed to study the electronic structure of cuprate superconductors in the superconducting-state. In particular, it is shown that the underlying electron Fermi surface fulfills Luttinger's theorem, while the superconducting coherence of the low-energy quasiparticle excitations is qualitatively described by the standard d-wave Bardeen-Cooper-Schrieffer formalism. The theory also shows that the observed peak-dip-hump structure in the electron spectrum and Fermi arc behavior in the underdoped regime are mainly caused by the strong energy and momentum dependence of the electron self-energy.

  14. Collective nature of spin excitations in superconducting cuprates probed by resonant inelastic X-ray scattering.

    PubMed

    Minola, M; Dellea, G; Gretarsson, H; Peng, Y Y; Lu, Y; Porras, J; Loew, T; Yakhou, F; Brookes, N B; Huang, Y B; Pelliciari, J; Schmitt, T; Ghiringhelli, G; Keimer, B; Braicovich, L; Le Tacon, M

    2015-05-29

    We used resonant inelastic x-ray scattering (RIXS) with and without analysis of the scattered photon polarization, to study dispersive spin excitations in the high temperature superconductor YBa_{2}Cu_{3}O_{6+x} over a wide range of doping levels (0.1≤x≤1). The excitation profiles were carefully monitored as the incident photon energy was detuned from the resonant condition, and the spin excitation energy was found to be independent of detuning for all x. These findings demonstrate that the largest fraction of the spin-flip RIXS profiles in doped cuprates arises from magnetic collective modes, rather than from incoherent particle-hole excitations as recently suggested theoretically [Benjamin et al. Phys. Rev. Lett. 112, 247002 (2014)]. Implications for the theoretical description of the electron system in the cuprates are discussed. PMID:26066453

  15. Perspective on the phase diagram of cuprate high-temperature superconductors.

    PubMed

    Rybicki, Damian; Jurkutat, Michael; Reichardt, Steven; Kapusta, Czesław; Haase, Jürgen

    2016-01-01

    Universal scaling laws can guide the understanding of new phenomena, and for cuprate high-temperature superconductivity the influential Uemura relation showed, early on, that the maximum critical temperature of superconductivity correlates with the density of the superfluid measured at low temperatures. Here we show that the charge content of the bonding orbitals of copper and oxygen in the ubiquitous CuO2 plane, measured with nuclear magnetic resonance, reproduces this scaling. The charge transfer of the nominal copper hole to planar oxygen sets the maximum critical temperature. A three-dimensional phase diagram in terms of the charge content at copper as well as oxygen is introduced, which has the different cuprate families sorted with respect to their maximum critical temperature. We suggest that the critical temperature could be raised substantially if one were able to synthesize materials that lead to an increased planar oxygen hole content at the expense of that of planar copper. PMID:27150719

  16. Enhancement of superconductivity via periodic modulation in a three-dimensional model of cuprates

    NASA Astrophysics Data System (ADS)

    Raines, Zachary M.; Stanev, Valentin; Galitski, Victor M.

    2015-05-01

    Recent experiments in the cuprates have seen evidence of a transient superconducting state upon optical excitation polarized along the c axis [R. Mankowsky et al., Nature (London) 516, 71 (2014), 10.1038/nature13875]. Motivated by these experiments, we propose an extension of the single-layer t -J -V model of cuprates to three dimensions in order to study the effects of interplane tunneling on the competition between superconductivity and bond density wave order. We find that an optical pump can suppress the charge order and simultaneously enhance superconductivity, due to the inherent competition between the two. We also provide an intuitive picture of the physical mechanism underlying this effect. Furthermore, based on a simple Floquet theory, we estimate the magnitude of the enhancement.

  17. Strong-coupling superconductivity, the Lorenz number, and the Nernst effect in cuprates

    NASA Astrophysics Data System (ADS)

    Alexandrov, Sasha

    2004-03-01

    Strong electron-phonon interaction in the cuprates has gathered support over the last decade in a large number of experiments. Here I argue that the bipolaron extension of the BCS theory to the strong-coupling regime [1] naturally explains the temperature dependent Lorenz number and the large Nernst effect in the cuprates. The Wiedemann-Franz law breaks down due to the interference of polaron and bipolaron contributions to the heat flow that provides a quantitative fit to the experimental "Hall" Lorenz number [2]. A strong enhancement of the Nernst signal and its magnetic field dependence above Tc originate in a critical slowing down of the bipolaron relaxation times, when the system approaches the Bose-Einstein condensation. [1] A.S. Alexandrov, Theory of superconductivity: from weak to strong coupling, IOP Publishing (Bristol-Philadelphia, 2003) [2] K. K. Lee, A. S. Alexandrov, and W. Y. Liang, Phys. Rev. Lett. 90, 217001 (2003)

  18. Berry phases and the intrinsic thermal Hall effect in high-temperature cuprate superconductors.

    PubMed

    Cvetkovic, Vladimir; Vafek, Oskar

    2015-01-01

    Bogolyubov quasiparticles move in a practically uniform magnetic field in the vortex state of high-temperature cuprate superconductors. When set in motion by an externally applied heat current, the quasiparticles' trajectories may bend, causing a temperature gradient perpendicular to the heat current and the applied magnetic field, resulting in the thermal Hall effect. Here we relate this effect to the Berry curvature of quasiparticle magnetic sub-bands, and calculate the dependence of the intrinsic thermal Hall conductivity on superconductor's temperature, magnetic field and the amplitude of the d-wave pairing. The intrinsic contribution to thermal Hall conductivity displays a rapid onset with increasing temperature, which compares favourably with existing experiments at high magnetic field on the highest purity samples. Because such temperature onset is related to the pairing amplitude, our finding may help to settle a much-debated question of the bulk value of the pairing strength in cuprate superconductors in magnetic field. PMID:25758469

  19. Comment on "Berry phase mechanism for optical gyrotropy in stripe-ordered cuprates"

    NASA Astrophysics Data System (ADS)

    Chakravarty, Sudip

    2014-02-01

    I comment on two recent papers on the Kerr effect as evidence of gyrotropic order in cuprates, and I suggest that the arguments may not be sound. The difficulty is that, in practically all cases, the wave vector kz perpendicular to the copper-oxygen plane is not a good quantum number. This appears to be problematic for Orenstein and Moore [Phys. Rev. B 87, 165110 (2013), 10.1103/PhysRevB.87.165110], whereas, in Hosur et al. [Phys. Rev. B 87, 115116 (2013), 10.1103/PhysRevB.87.115116], the symmetry arguments may turn out to be robust, but the microscopic picture is wanting. Thus, the Kerr effect in cuprates remains a puzzle as there is little doubt that the arguments presented against time-reversal symmetry breaking appear to be rather strong on experimental grounds in both of these papers.

  20. A pseudogap term in the magnetic response of the cuprate superconductors

    SciTech Connect

    Walstedt, Professor Russell E.; Mason, Dr. Thomas Edward; Aeppli, Professor Gabriel; Hayden, Professor Stephen M.; Mook Jr, Herbert A

    2011-01-01

    We combine neutron scattering (INS) data and NMR/NQR nuclear spin lattice relaxation rate (1/T1) data to deduce the existence of a new contribution to the magnetic response (~q, ) in cuprate superconductors. This contribution, which has yet to be observed with INS, is shown to embody the magnetic pseudogap effects. As such, it explains the long-standing puzzle of pseudogap effects missing from cuprate INS data, dominated by stripe fluctuations, for (~q, ) at low energies. For La1.86Sr0.14CuO4 and Y Ba2Cu3O6.5, the new term is the chief contributor to 1/T1 for T Tc.

  1. Perspective on the phase diagram of cuprate high-temperature superconductors

    PubMed Central

    Rybicki, Damian; Jurkutat, Michael; Reichardt, Steven; Kapusta, Czesław; Haase, Jürgen

    2016-01-01

    Universal scaling laws can guide the understanding of new phenomena, and for cuprate high-temperature superconductivity the influential Uemura relation showed, early on, that the maximum critical temperature of superconductivity correlates with the density of the superfluid measured at low temperatures. Here we show that the charge content of the bonding orbitals of copper and oxygen in the ubiquitous CuO2 plane, measured with nuclear magnetic resonance, reproduces this scaling. The charge transfer of the nominal copper hole to planar oxygen sets the maximum critical temperature. A three-dimensional phase diagram in terms of the charge content at copper as well as oxygen is introduced, which has the different cuprate families sorted with respect to their maximum critical temperature. We suggest that the critical temperature could be raised substantially if one were able to synthesize materials that lead to an increased planar oxygen hole content at the expense of that of planar copper. PMID:27150719

  2. Nematicity in stripe ordered cuprates probed via resonant x-ray scattering

    DOE PAGESBeta

    Achkar, A. J.; Zwiebler, M.; McMahon, Christopher; He, F.; Sutarto, R.; Dijianto, Isaiah; Hao, Zhihao; Gingras, Michael J.P.; Hucker, M.; Gu, G. D.; et al

    2016-02-05

    We found that in underdoped cuprate superconductors, a rich competition occurs between superconductivity and charge density wave (CDW) order. Whether rotational symmetry-breaking (nematicity) occurs intrinsically and generically or as a consequence of other orders is under debate. Here, we employ resonant x-ray scattering in stripe-ordered superconductors (La,M)2CuO4 to probe the relationship between electronic nematicity of the Cu 3d orbitals, structure of the (La,M)2O2 layers, and CDW order. We find distinct temperature dependences for the structure of the (La,M)2O2 layers and the electronic nematicity of the CuO2 planes, with only the latter being enhanced by the onset of CDW order. Ourmore » results identify electronic nematicity as an order parameter that is distinct from a purely structural order parameter in underdoped striped cuprates.« less

  3. Material and Doping Dependence of the Nodal and Antinodal Dispersion Renormalizations in Single- and Multilayer Cuprates

    DOE PAGESBeta

    Johnston, S.; Lee, W. S.; Chen, Y.; Nowadnick, E. A.; Moritz, B.; Shen, Z. -X.; Devereaux, T. P.

    2010-01-01

    We presenmore » t a review of bosonic renormalization effects on electronic carriers observed from angle-resolved photoemission spectra in the cuprates. Specifically, we discuss the viewpoint that these renormalizations represent coupling of the electrons to the lattice and review how materials dependence, such as the number of Cu O 2 layers, and doping dependence can be understood straightforwardly in terms of several aspects of electron-phonon coupling in layered correlated materials.« less

  4. Novel magnetic excitations in a model cuprate high-Tc superconductor

    NASA Astrophysics Data System (ADS)

    Li, Yuan

    2011-03-01

    Magnetic fluctuations might be essential to the mechanism of high-temperature superconductivity in the cuprates. For a long time, such fluctuations have been theoretically regarded as arising from the antiferromagnetic correlations within the copper-oxygen layers, and experimental studies of magnetic excitation spectrum have mainly been carried out near the corresponding wave vector (1/2,~1/2). Following neutron diffraction experiments which demonstrated the universal existence of a `` q ~=~0 antiferromagnetic order'' in the pseudogap phase of three different cuprates [1-3], our recent inelastic neutron scattering experiments on the model compound HgBa 2 Cu O4 + δ (Hg1201) revealed the existence of unusual magnetic excitations that weakly disperse throughout the entire Brillouin zone [4,5]. Like the q ~=~0 antiferromagnetic order, the new excitations are observed in the pseudogap phase and therefore appear to be associated with the order. The excitations possess very large spectral weights at well-defined characteristic energies that are comparable to the resonance energy and to those of electron-boson-coupling features observed in a wide range of cuprates, highlighting their possible influence on the electronic structure. These findings demonstrate that the pseudogap state is a distinct phase of matter rather than a mere crossover. They furthermore cast doubt on the presumed predominant importance of the wave vector (1/2,~1/2) in the magnetic excitation spectrum, and have the profound implication that a single-band description of the cuprates is insufficient. Project was funded by DOE and NSF grants. The author achnowledges the Alexander von Humboldt Foundation.

  5. Present status of the theory of the high-Tc cuprates

    NASA Astrophysics Data System (ADS)

    Anderson, P. W.

    2006-04-01

    The Gutzwiller-projected mean-field theory, also called plain vanilla or renormalized mean-field theory, is explained, and its successes and possible extensions in describing the phenomenology of the cuprate superconductors are discussed. Throughout, we emphasize that while this is a Hartree-Fock-based BCS theory, it embodies fundamental differences from conventional perturbative many-body theory which may be characterized by calling it a theory of the doped Mott insulator.

  6. Interplay of pair density wave and charge density wave order in the cuprate pseudogap phase

    NASA Astrophysics Data System (ADS)

    Agterberg, Daniel; Amin, Adil

    Recent x-ray measurements in the cuprate YBCO suggest that the charge density wave (CDW) order seen at high-field has a different c-axis structure than that seen at zero-field and further suggests that CDW order breaks the c-axis mirror plane symmetry of the CuO2 layers. We examine pair density wave order that induces CDW order consistent with these observations.

  7. On the Interpretation of the Nernst Effect Measurements in the Cuprates

    NASA Astrophysics Data System (ADS)

    Ussishkin, Iddo; Sondhi, S. L.

    We consider the large Nernst signal discovered by Ong and collaborators in hole-doped cuprates, in particular in the pseudogap regime. Based on our previous quantitative calculations together with Huse [Phys. Rev. Lett. 89, 287001 (2002)], we discuss the interpretation of the experimental observations as arising from superconducting fluctuations and its relation to the vortex scenario proposed by Ong. We also comment on the implications of the Nernst analysis for understanding the full range of pseudogap phenomena.

  8. Itinerant effects and enhanced magnetic interactions in Bi-based multilayer cuprates

    DOE PAGESBeta

    Dean, M. P. M.; James, A. J. A.; Walters, A. C.; Bisogni, V.; Jarrige, I.; Hücker, M.; Giannini, E.; Fujita, M.; Pelliciari, J.; Huang, Y. B.; et al

    2014-12-04

    The cuprate high temperature superconductors exhibit a pronounced trend in which the superconducting transition temperature, T c, increases with the number of CuO₂ planes, n, in the crystal structure. We compare the magnetic excitation spectrum of Bi₂₊xSr₂₋xCuO₆+δ (Bi-2201) and Bi₂Sr₂Ca₂Cu₃O₁₀₊δ (Bi-2223), with n = 1 and n = 3 respectively, using Cu L₃-edge resonant inelastic x-ray scattering (RIXS). Near the anti-nodal zone boundary we find the paramagnon energy in Bi-2223 is substantially higher than that in Bi-2201, indicating that multilayer cuprates host stronger effective magnetic exchange interactions, providing a possible explanation for the Tc vs. n scaling. In contrast, themore » nodal direction exhibits very strongly damped, almost non-dispersive excitations. As a result, we argue that this implies that the magnetism in the doped cuprates is partially itinerant in nature.« less

  9. Power-law optical conductivity from unparticles: Application to the cuprates

    NASA Astrophysics Data System (ADS)

    Limtragool, Kridsanaphong; Phillips, Philip

    2015-10-01

    We calculate the optical conductivity by using several models for unparticle or scale-invariant matter. Within a Gaussian action for unparticles that is gauged with Wilson lines, we find that the conductivity computed from the Kubo formalism with vertex corrections yields no nontrivial deviation from the free-theory result. This result obtains because, at the Gaussian level, unparticles are just a superposition of particle fields and hence any transport property must be consistent with free theory. Beyond the Gaussian approach, we adopt the continuous-mass formulation of unparticles and calculate the Drude conductivity directly. We show that unparticles in this context can be tailored to yield an algebraic conductivity that scales as ω-2 /3 with the associated phase angle between the imaginary and real parts of arctanσ/2σ1=60∘ , as is seen in the cuprates. Given the recent results [J. High Energy Phys. 4, 40 (2014), 10.1007/JHEP04(2014)040; J. High Energy Phys. 7, 24 (2015), 10.1007/JHEP07(2015)024; arXiv:1506.06769] that gravitational crystals lack a power-law optical conductivity, this constitutes the first consistent account of the ω-2 /3 conductivity and the phase angle seen in optimally doped cuprates. Our results indicate that, at each frequency in the scaling regime, excitations on all energy scales contribute. Hence, incoherence is at the heart of the power law in the optical conductivity in strongly correlated systems such as the cuprates.

  10. Crystal structure of the thermochromic bis-(di-ethyl-ammonium) tetra-chlorido-cuprate(II) complex.

    PubMed

    Aldrich, Emily P; Bussey, Katherine A; Connell, Jennifer R; Reinhart, Erin F; Oshin, Kayode D; Mercado, Brandon Q; Oliver, Allen G

    2016-01-01

    In the structure of the title complex salt, (Et2NH2)2[CuCl4], the asymmetric unit consists of four unique di-ethyl-ammonium cations and three unique tetra-chlorido-cuprate anions. Two of the three anions are located with their copper atoms on independent crystallographic twofold axes, while the remaining tetra-chlorido-cuprate is located at a general position of the ortho-rhom-bic space group P21212. Two of the three Cu atoms adopt a distorted square-planar/disphenoidal geometry and the third Cu atom has a regular square-planar coordination environment. The di-ethyl-ammonium cations form an extensive hydrogen-bonded network through N-H⋯Cl inter-actions with the tetra-chlorido-cuprate anions, resulting in a two-dimensional sheet-like hydrogen-bonded network parallel to the ab direction. The complex was observed to undergo a color shift from deep green at room temperature to pale yellow at temperatures above 328 K. PMID:26870581

  11. Probing broken symmetry states in cuprate superconductors with polarization-sensitive infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Mukherjee, Alok; Arik, Mumtaz Murat; Seo, Jungryeol; Cerne, John; Zhang, Hao; Xu, Ke Jun; Wei, John Y. T.; Armitage, N. P.; Kirzhner, T.; Koren, G.

    The nature of the pseudogap state in high-temperature superconducting (HTS) cuprates has drawn a lot of attention in the past two decades. A fundamental question is whether the pseudogap is a distinct phase with its own broken symmetries. Recent optical studies in the near-IR (800 meV) and THz (2-6 meV) ranges have observed symmetry breaking in the pseudogap state of HTS cuprates, suggesting that the pseudogap is a distinct phase. To probe the spectral character of this broken symmetry, we have performed infrared/visible Faraday and Kerr effect measurements at zero magnetic field and various temperatures on a series of HTS cuprate thin films, grown epitaxially by pulsed laser-ablated deposition. We will present and discuss our data, primarily complex Faraday/Kerr angle as a function of energy (0.1-3 eV), temperature (10-300K) and sample orientation with respect to the incident light polarization. This work supported by NSF-DMR1410599, NSERC, CFI-OIT and the Canadian Institute for Advanced Research.

  12. Direct phase-sensitive identification of a d-form factor density wave in underdoped cuprates

    PubMed Central

    Fujita, Kazuhiro; Hamidian, Mohammad H.; Edkins, Stephen D.; Kim, Chung Koo; Kohsaka, Yuhki; Azuma, Masaki; Takano, Mikio; Takagi, Hidenori; Eisaki, Hiroshi; Uchida, Shin-ichi; Allais, Andrea; Lawler, Michael J.; Kim, Eun-Ah; Sachdev, Subir; Davis, J. C. Séamus

    2014-01-01

    The identity of the fundamental broken symmetry (if any) in the underdoped cuprates is unresolved. However, evidence has been accumulating that this state may be an unconventional density wave. Here we carry out site-specific measurements within each CuO2 unit cell, segregating the results into three separate electronic structure images containing only the Cu sites [Cu(r)] and only the x/y axis O sites [Ox(r) and Oy(r)]. Phase-resolved Fourier analysis reveals directly that the modulations in the Ox(r) and Oy(r) sublattice images consistently exhibit a relative phase of π. We confirm this discovery on two highly distinct cuprate compounds, ruling out tunnel matrix-element and materials-specific systematics. These observations demonstrate by direct sublattice phase-resolved visualization that the density wave found in underdoped cuprates consists of modulations of the intraunit-cell states that exhibit a predominantly d-symmetry form factor. PMID:24989503

  13. Universality of commensurate 4 a-period charge density modulations throughout the cuprate pseudogap regime

    NASA Astrophysics Data System (ADS)

    Mesaros, Andrej; Fujita, Kazuhiro; Hamidian, Mohammad; Eisaki, Hiroshi; Uchida, Shin-Ichi; Davis, J. C.; Lawler, Michael J.; Kim, Eun-Ah

    Theories for the hole-doped Mott insulator, representing underdoped cuprates, are based upon the strong real space (r-space) interactions, and have long predicted a modulation of charge that is commensurate with the underlying lattice. Such a charge density modulation (CDM) state is unrelated to any momentum space (k-space) features such as the nesting of regions on a Fermi surface. Experimentally, with increasing hole density, the reported wavevector Q of the CDM diminishes continuously with increasing hole-density as if driven by k-space phenomena. Using a novel technique based upon phase-sensitive electronic structure visualization, we demonstrate that the cuprate CDM actually exhibits a commensurate 4 a-period throughout the entire underdoped region of the Bi2 Sr2 CaCu2O8 phase diagram. Our technique is designed for extracting Q from inhomogeneous, short-ranged CDM, as the ones observed in experiments. Thus, a strong-interaction r-space perspective appears to be relevant to achieving a predictive theory for the cuprate pseudogap regime.

  14. Progress in Neutron Scattering Studies of Spin Excitations in High-T(c) Cuprates

    SciTech Connect

    Fujita M.; Tranquada J.; Hiraka, H.; Matsuda, M.; Matsuura, M.; Wakimoto, S.; Xu, G.; Yamada, K.

    2012-01-01

    Neutron scattering experiments continue to improve our knowledge of spin fluctuations in layered cuprates, excitations that are symptomatic of the electronic correlations underlying high-temperature superconductivity. Time-of-flight spectrometers, together with new and varied single crystal samples, have provided a more complete characterization of the magnetic energy spectrum and its variation with carrier concentration. While the spin excitations appear anomalous in comparison with simple model systems, there is clear consistency among a variety of cuprate families. Focusing initially on hole-doped systems, we review the nature of the magnetic spectrum, and variations in magnetic spectral weight with doping. We consider connections with the phenomena of charge and spin stripe order, and the potential generality of such correlations as suggested by studies of magnetic-field and impurity induced order. We contrast the behavior of the hole-doped systems with the trends found in the electron-doped superconductors. Returning to hole-doped cuprates, studies of translation-symmetry-preserving magnetic order are discussed, along with efforts to explore new systems. We conclude with a discussion of future challenges.

  15. Interpretation of Scanning Tunneling Quasiparticle Interference and Impurity States in Cuprates

    SciTech Connect

    Kreisel, A.; Choubey, P.; Berlijn, T.; Ku, W.; Andersen, B. M.; Hirschfeld, P. J.

    2015-05-27

    We apply a recently developed method combining first principles based Wannier functions with solutions to the Bogoliubov-de Gennes equations to the problem of interpreting STM data in cuprate superconductors. We show that the observed images of Zn on the surface of Bi2Sr2CaCu2O8 can only be understood by accounting for the tails of the Cu Wannier functions, which include significant weight on apical O sites in neighboring unit cells. This calculation thus puts earlier crude “filter” theories on a microscopic foundation and solves a long standing puzzle. We then study quasiparticle interference (QPI) phenomena induced by out-of-plane weak potential scatterers, and show how patterns long observed in cuprates can be understood in terms of the interference of Wannier functions above the surface. Our results show excellent agreement with experiment and enable a better understanding of novel phenomena in the cuprates via STM imaging.

  16. Interpretation of scanning tunneling quasiparticle interference and impurity states in cuprates

    SciTech Connect

    Kreisel, Andreas; Choubey, Peayush; Berlijn, Tom; Ku, W.; Andersen, Brian M.; Hirschfeld, Peter J.

    2015-05-27

    We apply a recently developed method combining first principles based Wannier functions with solutions to the Bogoliubov–de Gennes equations to the problem of interpreting STM data in cuprate superconductors. We show that the observed images of Zn on the surface of Bi2Sr2CaCu2O8 can only be understood by accounting for the tails of the Cu Wannier functions, which include significant weight on apical O sites in neighboring unit cells. This calculation thus puts earlier crude “filter” theories on a microscopic foundation and solves a long-standing puzzle. We then study quasiparticle interference phenomena induced by out-of-plane weak potential scatterers, and show how patterns long observed in cuprates can be understood in terms of the interference of Wannier functions above the surface. Furthermore, our results show excellent agreement with experiment and enable a better understanding of novel phenomena in the cuprates via STM imaging.

  17. Interpretation of Scanning Tunneling Quasiparticle Interference and Impurity States in Cuprates

    DOE PAGESBeta

    Kreisel, A.; Choubey, P.; Berlijn, T.; Ku, W.; Andersen, B. M.; Hirschfeld, P. J.

    2015-05-27

    We apply a recently developed method combining first principles based Wannier functions with solutions to the Bogoliubov-de Gennes equations to the problem of interpreting STM data in cuprate superconductors. We show that the observed images of Zn on the surface of Bi2Sr2CaCu2O8 can only be understood by accounting for the tails of the Cu Wannier functions, which include significant weight on apical O sites in neighboring unit cells. This calculation thus puts earlier crude “filter” theories on a microscopic foundation and solves a long standing puzzle. We then study quasiparticle interference (QPI) phenomena induced by out-of-plane weak potential scatterers, andmore » show how patterns long observed in cuprates can be understood in terms of the interference of Wannier functions above the surface. Our results show excellent agreement with experiment and enable a better understanding of novel phenomena in the cuprates via STM imaging.« less

  18. Interpretation of scanning tunneling quasiparticle interference and impurity states in cuprates

    DOE PAGESBeta

    Kreisel, Andreas; Choubey, Peayush; Berlijn, Tom; Ku, W.; Andersen, Brian M.; Hirschfeld, Peter J.

    2015-05-27

    We apply a recently developed method combining first principles based Wannier functions with solutions to the Bogoliubov–de Gennes equations to the problem of interpreting STM data in cuprate superconductors. We show that the observed images of Zn on the surface of Bi2Sr2CaCu2O8 can only be understood by accounting for the tails of the Cu Wannier functions, which include significant weight on apical O sites in neighboring unit cells. This calculation thus puts earlier crude “filter” theories on a microscopic foundation and solves a long-standing puzzle. We then study quasiparticle interference phenomena induced by out-of-plane weak potential scatterers, and show howmore » patterns long observed in cuprates can be understood in terms of the interference of Wannier functions above the surface. Furthermore, our results show excellent agreement with experiment and enable a better understanding of novel phenomena in the cuprates via STM imaging.« less

  19. Effective single-band models for the high-Tc cuprates. II. Role of apical oxygen

    NASA Astrophysics Data System (ADS)

    Raimondi, R.; Jefferson, J. H.; Feiner, L. F.

    1996-04-01

    An effective single-band model for the cuprates is derived by a cell-perturbation method from a five-band model which includes d3z2-r2 orbitals on copper and pz orbitals on apical oxygen. In addition to the usual Zhang-Rice singlets of A1 symmetry, there are two-hole cell states of B1 symmetry, which can become low in energy and depend sensitively on the apical oxygen ions. Provided that hybridization with the apical oxygen orbital is sufficiently weak to permit reduction to a t-t'-J model, the main effect of the B1-symmetry states is to renormalize the effective next-nearest-neighbor hopping (t') of doped holes. This effect can be quite large and may even change the sign of t'. The variation of t' between various compounds due to differences in crystal structure is shown to correlate with Tmaxc, the critical temperature at optimum doping, suggesting that t' may be a crucial parameter for the low-energy physics, which moreover differentiates between the various cuprates. The effective single-band model is shown to break down when the apex level approaches the in-plane oxygen level, and to describe that situation, which cannot be ruled out completely for the cuprates with present experimental evidence, we propose a specific minimal effective (two-band) model.

  20. Pseudogap phase in cuprates: Oxygen orbital moments instead of circulating currents

    NASA Astrophysics Data System (ADS)

    Moskvin, A. S.

    2012-11-01

    Circulating current loops within the cuprate unit cell are proposed to play a key role in the physics of the pseudogap phase. However, main experimental observations motivated by this sophisticated proposal and seemingly supporting the circulating current model can be explained within a simple and physically clear microscopic model. It has been argued that, instead of a well-isolated Zhang-Rice (ZR) singlet 1 A 1 g , the ground state of the hole center [CuO4]5- (cluster analog of Cu3+ ion) in cuprates should be described by a complex 1 A 1 g -1,3 B 2 g -1,3 E u multiplet, formed by a competition of conventional hybrid Cu 3 d-O 2 p b_{1g} (σ ) ∝ d_{x^2 - y^2 } state and purely oxygen nonbonding O 2 pπ states with a 2 g (π) and e ux, y (π) symmetry. In contrast to inactive ZR singlet we arrive at several novel competing orbital and spin-orbital order parameters, e.g., Ising-like net orbital magnetic moment, orbital toroidal moment, intra-plaquette's staggered order of Ising-like oxygen orbital magnetic moments. As a most impressive validation of the non-ZR model we explain fascinating results of recent neutron scattering measurements that revealed novel type of magnetic ordering in pseudogap phase of several hole-doped cuprates.

  1. TOPICAL REVIEW: The physics behind high-temperature superconducting cuprates: the 'plain vanilla' version of RVB

    NASA Astrophysics Data System (ADS)

    Anderson, P. W.; Lee, P. A.; Randeria, M.; Rice, T. M.; Trivedi, N.; Zhang, F. C.

    2004-06-01

    One of the first theoretical proposals for understanding high-temperature superconductivity in the cuprates was Anderson's RVB theory using a Gutzwiller projected BCS wavefunction as an approximate ground state. Recent work by Paramekanti et al has shown that this variational approach gives a semi-quantitative understanding of the doping dependences of a variety of experimental observables in the superconducting state of the cuprates. In this paper we revisit these issues using the 'renormalized mean field theory' of Zhang et al based on the Gutzwiller approximation in which the kinetic and superexchange energies are renormalized by different doping-dependent factors gt and gS respectively. We point out a number of consequences of this early mean field theory for experimental measurements which were not available when it was first explored, and observe that it is able to explain the existence of the pseudogap, properties of nodal quasiparticles and approximate spin-charge separation, the latter leading to large renormalizations of the Drude weight and superfluid density. We use the Lee-Wen theory of the phase transition as caused by thermal excitation of nodal quasiparticles, and also obtain a number of further experimental confirmations. Finally, we remark that superexchange, and not phonons, is responsible for d-wave superconductivity in the cuprates.

  2. Relationship between critical temperature and core orbital coupling in cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Zhao, Bo; Chen, Ning

    2016-04-01

    Because superconductivity and several relevant phenomena of high-temperature superconductors (HTSCs) arise from interactions of valence electrons near the Fermi surface, the valence orbital coupling has usually been thought to be critical to understanding the electronic pairing mechanism which seems work without the core coupling orbitals. But, as strong electronic correlations are believed to be essential for a comprehensive understanding of the cuprate superconductors, the Fermi surface is influenced directly or indirectly by all orbital couplings in the entire energy band. In this paper, we focused on the core orbital coupling which arises from the overlap between the Oxygen's 2 s core orbital and the core p orbital of neighboring ion of CuO2 layers as they have a similar energy level ranging from -12 ∼ -23 eV below the Fermi level. The characters of this core coupling are varied with different kinds of neighboring ions or from the crystal structures. Based on the experimental superconducting critical temperature (Tc) data, we found that the binding energy differences between the valence couplings and the core couplings are positively related with the systemic Tc values for all cuprate superconductors. Obviously, this relationship suggests that the electron pairing nature of superconductivity for all cuprates might arise from the sp core orbital coupling.

  3. Underlying mechanisms of pseudogap phenomena and Bose-liquid superconductivity in high-Tc cuprates

    NASA Astrophysics Data System (ADS)

    Dzhumanov, S.; Karimboev, E. X.; Djumanov, Sh. S.

    2016-06-01

    We show that the high-Tc cuprates are non-BCS superconductors exhibiting distinct pseudogap (PG) behaviors (related to real and momentum space excitations) and other anomalies above Tc, novel Bose-liquid superconductivity below Tc, and also a λ-like superconducting (SC) transition at Tc similar to the λ transition in liquid 4He. In these materials, the relevant charge carriers are polarons which are bound into bosonic Cooper pairs above Tc followed by condensing into a Bose superfluid at Tc. We found that the polaronic effects and related PG weaken with increasing of the doping level and disappear in the overdoped region, where the crossover from Bose-liquid to Fermi-liquid (BCS-type) superconductivity occurs at the quantum critical point. We identify the real phase diagrams of the cuprates, the PG and vortex-like states above Tc, the novel SC state and two distinct SC phases below Tc like two superfluid phases of 3He, and explain the rich cuprate phenomenology from lightly doped to overdoped region.

  4. Inverse correlation between quasiparticle mass and Tc in a cuprate high-Tc superconductor

    PubMed Central

    Putzke, Carsten; Malone, Liam; Badoux, Sven; Vignolle, Baptiste; Vignolles, David; Tabis, Wojciech; Walmsley, Philip; Bird, Matthew; Hussey, Nigel E.; Proust, Cyril; Carrington, Antony

    2016-01-01

    Close to a zero-temperature transition between ordered and disordered electronic phases, quantum fluctuations can lead to a strong enhancement of electron mass and to the emergence of competing phases such as superconductivity. A correlation between the existence of such a quantum phase transition and superconductivity is quite well established in some heavy fermion and iron-based superconductors, and there have been suggestions that high-temperature superconductivity in copper-oxide materials (cuprates) may also be driven by the same mechanism. Close to optimal doping, where the superconducting transition temperature Tc is maximal in cuprates, two different phases are known to compete with superconductivity: a poorly understood pseudogap phase and a charge-ordered phase. Recent experiments have shown a strong increase in quasiparticle mass m* in the cuprate YBa2Cu3O7-δ as optimal doping is approached, suggesting that quantum fluctuations of the charge-ordered phase may be responsible for the high-Tc superconductivity. We have tested the robustness of this correlation between m* and Tc by performing quantum oscillation studies on the stoichiometric compound YBa2Cu4O8 under hydrostatic pressure. In contrast to the results for YBa2Cu3O7-δ, we find that in YBa2Cu4O8, the mass decreases as Tc increases under pressure. This inverse correlation between m* and Tc suggests that quantum fluctuations of the charge order enhance m* but do not enhance Tc. PMID:27034989

  5. Inverse correlation between quasiparticle mass and T c in a cuprate high-T c superconductor.

    PubMed

    Putzke, Carsten; Malone, Liam; Badoux, Sven; Vignolle, Baptiste; Vignolles, David; Tabis, Wojciech; Walmsley, Philip; Bird, Matthew; Hussey, Nigel E; Proust, Cyril; Carrington, Antony

    2016-03-01

    Close to a zero-temperature transition between ordered and disordered electronic phases, quantum fluctuations can lead to a strong enhancement of electron mass and to the emergence of competing phases such as superconductivity. A correlation between the existence of such a quantum phase transition and superconductivity is quite well established in some heavy fermion and iron-based superconductors, and there have been suggestions that high-temperature superconductivity in copper-oxide materials (cuprates) may also be driven by the same mechanism. Close to optimal doping, where the superconducting transition temperature T c is maximal in cuprates, two different phases are known to compete with superconductivity: a poorly understood pseudogap phase and a charge-ordered phase. Recent experiments have shown a strong increase in quasiparticle mass m* in the cuprate YBa2Cu3O7-δ as optimal doping is approached, suggesting that quantum fluctuations of the charge-ordered phase may be responsible for the high-T c superconductivity. We have tested the robustness of this correlation between m* and T c by performing quantum oscillation studies on the stoichiometric compound YBa2Cu4O8 under hydrostatic pressure. In contrast to the results for YBa2Cu3O7-δ, we find that in YBa2Cu4O8, the mass decreases as T c increases under pressure. This inverse correlation between m* and T c suggests that quantum fluctuations of the charge order enhance m* but do not enhance T c. PMID:27034989

  6. 2011 Aspen Winter Conference on Contrasting Superconductivity of Pnictides and Cuprates

    SciTech Connect

    Johnson, P.; Schmalian, J.; Canfield, P.; Chakravarty, S.

    2011-05-02

    Our quest for materials with better properties is closely integral to the fabric of our society. Currently the development of materials that will allow for improved generation, transport, and storage of energy is at the forefront of our research in condensed matter physics and materials science. Among these materials, compounds that exhibit correlated electron states and emergent phenomena such as superconductivity have great promise, but also difficulties that need to be overcome: problems associated with our need to reliably find, understand, improve and control these promising materials. At the same time, the field of correlated electrons represents the frontier of our understanding of the electronic properties of solids. It contains deep open scientific issues within the broad area of quantum phenomena in matter. The aim of this workshop is to explore and understand the physics of recently discovered Fe-based high-temperature superconductors and contrast and compare them with the cuprates. The superconductivity in iron pnictides, with transition temperatures in excess of 55 K, was discovered in early 2008. The impact of this discovery is comparable to cuprates discovered in 1986. At the same time a number of recent experimental developments in cuprates may lead to a shift in our thinking with regards to these materials. There is therefore much to be learned by devoting a conference in which both classes of superconductors are discussed, especially at this nascent stage of the pnictides.

  7. Earth Resources

    ERIC Educational Resources Information Center

    Brewer, Tom

    1970-01-01

    Reviews some of the more concerted, large-scale efforts in the earth resources areas" in order to help the computer community obtain insights into the activities it can jointly particpate in withthe earth resources community." (Author)

  8. Recent high-magnetic-field experiments on the 'high Tc' cuprates: Fermi-surface instabilities as a driver for superconductivity

    SciTech Connect

    Singleton, John; Mc Donald, Ross D; Cox, Susan

    2008-01-01

    The authors give a brief review of high-magnetic-field quantum-oscillation measurements on cuprate superconductors. In the case of the underdoped cuprates, a number of small Fermi-surface pockets are observed, probably due to the incommensurate nesting of the predicted (large) hole Fermi surface. The Fermi-surface instabilities that drive this nesting are also likely to result in the incommensurate spin fluctuations observed in inelastic neutron-scattering measurements. They suggest that the unusually high superconducting transitions in the cuprates are driven by an exact mapping of these incommensurate spin fluctuations onto the d{sub x{sup 2}-y{sup 2}} Cooper-pair wavefunction. The maximum energy of the fluctuations {approx} 100s of Kelvin gives an appropriate energy scale for the superconducting transition temperature.

  9. Phase fluctuation in overdoped cuprates? Superconducting dome due to Mott-ness of the tightly bound preformed pairs

    NASA Astrophysics Data System (ADS)

    Ku, Wei; Yang, Fan

    2015-03-01

    In contrast to the current lore, we demonstrate that even the overdoped cuprates suffer from superconducting phase fluctuation in the strong binding limit. Specifically, the Mott-ness of the underlying doped holes dictates naturally a generic optimal doping around 15% and nearly complete loss of phase coherence around 25%, giving rise to a dome shape of superconducting transition temperature in excellent agreement with experimental observations of the cuprates. We verify this effect with a simple estimation using Gutzwiller approximation of the preformed pairs, obtained through variational Monte Carlo calculation. This realization suggests strongly the interesting possibility that the high-temperature superconductivity in the cuprates might be mostly described by Bose-Einstein condensation, without crossing over to amplitude fluctuating Cooper pairs. Supported by Department of Energy, Office of Basic Energy Science DE-AC02-98CH10886.

  10. Electric Charge Transfer and Scattering of Its Carriers in Cuprates of the 1-2-3 System

    NASA Astrophysics Data System (ADS)

    Vovk, R. V.; Khadzhai, G. Ya.; Dobrovolskiy, O. V.; Kamchatnaya, S. N.; Nazyrov, Z. F.

    2016-04-01

    We show that the temperature dependences of the basal-plane electrical resistance in cuprates of the 1-2-3 system can be described as a consequence of scattering of charge carriers on phonons and defects in conjunction with the fluctuation conductivity. The electron-phonon parameters values deduced from fitting the experimental data to recognized models are close to those for metallic alloys of complex composition. It is revealed that at a large oxygen deficit (low superconducting transition temperatures T_c), the superconducting behavior of the studied cuprates has similarities with that of complex superconducting alloys. At the optimum oxygen deficit (maximal T_cs), superconductivity in the investigated cuprates is likely governed by some other mechanisms.

  11. Discover Earth

    NASA Technical Reports Server (NTRS)

    Steele, Colleen

    1998-01-01

    Discover Earth is a NASA-sponsored project for teachers of grades 5-12, designed to: (1) enhance understanding of the Earth as an integrated system; (2) enhance the interdisciplinary approach to science instruction; and (3) provide classroom materials that focus on those goals. Discover Earth is conducted by the Institute for Global Environmental Strategies in collaboration with Dr. Eric Barron, Director, Earth System Science Center, The Pennsylvania State University; and Dr. Robert Hudson, Chair, the Department of Meteorology, University of Maryland at College Park. The enclosed materials: (1) represent only part of the Discover Earth materials; (2) were developed by classroom teachers who are participating in the Discover Earth project; (3) utilize an investigative approach and on-line data; and (4) can be effectively adjusted to classrooms with greater/without technology access. The Discover Earth classroom materials focus on the Earth system and key issues of global climate change including topics such as the greenhouse effect, clouds and Earth's radiation balance, surface hydrology and land cover, and volcanoes and climate change. All the materials developed to date are available on line at (http://www.strategies.org) You are encouraged to submit comments and recommendations about these materials to the Discover Earth project manager, contact information is listed below. You are welcome to duplicate all these materials.

  12. Emery vs. Hubbard model for cuprate superconductors: a composite operator method study

    NASA Astrophysics Data System (ADS)

    Avella, Adolfo; Mancini, Ferdinando; Mancini, Francesco Paolo; Plekhanov, Evgeny

    2013-06-01

    Within the composite operator method (COM), we report the solution of the Emery model (also known as p- d or three band model), which is relevant for the cuprate high- T c superconductors. We also discuss the relevance of the often-neglected direct oxygen-oxygen hopping for a more accurate, sometimes unique, description of this class of materials. The benchmark of the solution is performed by comparing our results with the available quantum Monte Carlo ones. Both single-particle and thermodynamic properties of the model are studied in detail. Our solution features a metal-insulator transition at half filling. The resulting metal-insulator phase diagram agrees qualitatively very well with the one obtained within dynamical mean-field theory. We discuss the type of transition (Mott-Hubbard (MH) or charge-transfer (CT)) for the microscopic (ab initio) parameter range relevant for cuprates getting, as expected a CT type. The emerging single-particle scenario clearly suggests a very close relation between the relevant sub-bands of the three- (Emery) and the single-band (Hubbard) models, thus providing an independent and non-perturbative proof of the validity of the mapping between the two models for the model parameters optimal to describe cuprates. Such a result confirms the emergence of the Zhang-Rice scenario, which has been recently questioned. We also report the behavior of the specific heat and of the entropy as functions of the temperature on varying the model parameters as these quantities, more than any other, depend on and, consequently, reveal the most relevant energy scales of the system.

  13. Intra unit cell electronic structure of the d-symmetry form factor density wave in the underdoped cuprates - Part II

    NASA Astrophysics Data System (ADS)

    Edkins, Stephen; Fujita, Kazuhiro; Hamidian, Mohammad; Kim, Chung Koo; MacKenzie, Andrew; Eisaki, Hiroshi; Uchida, Shinichi; Lawler, Michael; Kim, Eun-Ah; Sachdev, Subir; Davis, Seamus

    2015-03-01

    A central issue of cuprate superconductivity research is to understand the nature of the unknown phase called the pseudogap and its relationship to the d-wave superconductivity. To approach this we use spectroscopic imaging STM to study the electronic structure of Bi2Sr2CaCu2O8+δ. Using our recently developed technique of sub-lattice phase-resolved electronic structure visualization within each CuO2 unit-cell, we discovered a d-symmetry form factor density wave within the cuprate pseudogap state. In this talk, part II, we report on the electronic structure of the density wave and its interplay with superconductivity.

  14. Synthesis of a new layered cuprate, Gd 2CaBa 2Ti 2Cu 2O 12

    NASA Astrophysics Data System (ADS)

    Fukuoka, A.; Adachi, S.; Sugano, T.; Wu, X.-J.; Yamauchi, H.

    1994-10-01

    A new layered cuprate, Gd 2CaBa 2Ti 2Cu 2O 12, which has a perovskite-related structure, has been discovered. The crystal structure is investigated by powder X-ray diffraction, electron diffraction and Rietveld analysis. It has a tetragonal symmetry with lattice parameters a=3.894 Å and c=35.49 Å. In the crystal there are sheets consisting of CuO 5 pyramids, which is one of the common features of p-type high- Tc superconducting cuprates.

  15. Model Evidence of a Superconducting State with a Full Energy Gap in Small Cuprate Islands

    NASA Astrophysics Data System (ADS)

    Black-Schaffer, Annica M.; Golubev, Dmitri S.; Bauch, Thilo; Lombardi, Floriana; Fogelström, Mikael

    2013-05-01

    We investigate subdominant order parameters stabilizing at low temperatures in nanoscale high-Tc cuprate islands, motivated by the recent observation of a fully gapped state in nanosized YBa2Cu3O7-δ [D. Gustafsson et al., Nature Nanotech. 8, 25 (2013)]. Using complementary quasiclassical and tight-binding Bogoliubov-de Gennes methods, we show on distinctly different properties dependent on the symmetry being dx2-y2+is or dx2-y2+idxy. We find that a surface-induced dx2-y2+is phase creates a global spectroscopic gap which increases with an applied magnetic field, consistent with experimental observation.

  16. Short range smectic order driving long range nematic order: Example of cuprates

    DOE PAGESBeta

    Markiewicz, R. S.; Lorenzana, J.; Seibold, G.; Bansil, A.

    2016-01-27

    We present a model for describing the combined presence of nematic and ‘smectic’ or stripe-like orders seen in recent scanning tunneling microscopy (STM) experiments on cuprates. The smectic order is treated as an electronic charge density wave with an associated Peierls distortion or a ‘Pomeranchuk wave’. This primary order is restricted to nanoscale domains by disorder effects, while the secondary coupling to strain generates the nematic order with a considerably longer range. Lastly, a variety of experimental results are shown to be consistent with our theoretical predictions.

  17. Towards material-specific simulations of high-temperature superconducting cuprates

    NASA Astrophysics Data System (ADS)

    Schulthess, Thomas

    2006-03-01

    Simulations of high-temperature superconducting (HTSC) cuprates have typically fallen into two categories: (1) studies of generic models such as the two-dimensional (2D) Hubbard model, that are believed to capture the essential physics necessary to describe the superconducting state, and, (2) first principles electronic structure calculations that are based on the local density approximation (LDA) to density functional theory (DFT) and lead to materials specific models. With advent of massibely parallel vector supercomputers, such as the Cray X1E at ORNL, and cluster algorithms such as the Dynamical Cluster Approximation (DCA), it is now possible to systematically solve the 2D Hubbard model with Quantum Monte Carol (QMC) simulations and to establish that the model indeed describes d-wave superconductivity [1]. Furthermore, studies of a multi-band model with input parameters generated from LDA calculations demonstrate that the existence of a superconducting transition is very sensitive to the underlying band structure [2]. Application of the LDA to transition metal oxides is, however, hampered by spurious self-interactions that particularly affects localized orbitals. Here we apply the self-interaction corrected local spin-density method (SIC-LSD) to describe the electronic structure of the cuprates. It was recently applied with success to generate input parameters for simple models of Mn doped III-V semiconductors [3] and is known to properly describe the antiferromagnetic insulating ground state of the parent compounds of the HTSC cuprates. We will discus the models for HTSC cuprates derived from the SIC-LSD study and how the differences to the well-known LDA results impact the QMC-DCA simulations of the magnetic and superconducting properties. [1] T. A. Maier, M. Jarrell, T. C. Schulthess, P. R. C. Kent, and J. B. White, Phys. Rev. Lett. 95, 237001 (2005). [2] P. Kent, A. Macridin, M. Jarrell, T. Schulthess, O. Andersen, T. Dasgupta, and O. Jepsen, Bulletin of

  18. The Doping Dependence of the Ground State in the Electron-doped Cuprates

    NASA Astrophysics Data System (ADS)

    Greene, Richard L.

    2004-03-01

    The mechanism behind high-temperature superconductivity in the cuprates is not yet determined. Understanding the nature of the normal ground state at various dopings is important for the ultimate determination of the mechanism. Some theories suggest that excitations associated with a doping-dependent quantum phase transition (QPT) are an essential ingredient. So far the evidence for a QPT in the cuprates has been indirect and inconclusive. The electron-doped cuprates offer a distinct advantage over their hole-doped counterparts because the maximum critical magnetic field (H_c2) necessary to access the T=0 normal state is less than 10T. Here, I will present comprehensive measurements of the low-temperature (0.35K to 20K) ab-plane resistivity and Hall effect in the normal state (H>H_c2) of the electron-doped cuprate Pr_2-xCe_xCuO4 (PCCO) as a function of Ce doping. These measurements [1] strongly suggest a quantum critical point at x_c=0.165±0.005 with an associated quantum fluctuation regime at higher temperatures and at nearby dopings. I will also present tunneling results which show that a normal state pseudogap, of unknown origin, disappears near the same doping [2]. The nature of the QPT cannot be determined from our measurements but other results [3] on PCCO suggest an antiferromagnetic-metal to paramagnetic- metal phase transition. I will also report low-temperature specific heat and Raman scattering data in the superconducting state, which show that the superconducting gap anisotropy changes near the critical doping x_c. [1] Y. Dagan et al., cond-mat/0310475. [2] A. Biswas et al., Phys. Rev. B64, 104519 (2001); L. Alff et al., Nature 422, 698 (2003. [3] J. Sonier et al., Phys. Rev. Lett. 91, 147002 (2003); M. Fujita et al., cond-mat/0311269. In collaboration with Y. Dagan, H. Balci, G. Blumberg, C. Kendziora, and M.M.Qazilbash. Support from the NSF under DMR-0102350.

  19. Role of Strong Correlation in the Recent Angle-Resolved Photoemission Spectroscopy Experiments on Cuprate Superconductors

    SciTech Connect

    Yunoki, S.; Dagotto, Elbio R; Sorella, S.

    2005-01-01

    Motivated by recent photoemission experiments on cuprates, the low-lying excitations of a strongly correlated superconducting state are studied numerically. It is observed that along the nodal direction these low-lying one-particle excitations show a linear momentum dependence for a wide range of excitation energies and, thus, they do not present a kinklike structure. The nodal Fermi velocity vF, as well as other observables, are systematically evaluated directly from the calculated dispersions, and they are found to compare well with experiments. It is argued that the parameter dependence of v{sub F} is quantitatively explained by a simple picture of a renormalized Fermi velocity.

  20. Possibility of c-axis voltage steps for a cuprate superconductor in a resonant cavity

    NASA Astrophysics Data System (ADS)

    Tornes, I.; Stroud, D.

    2003-08-01

    Very anisotropic cuprate superconductors, such as BiSr2Ca2CuO8+x, when driven by currents parallel to the c axis, behave like stacks of underdamped Josephson junctions. Here, we analyze the possibility that such a stack can be caused to phase lock, to exhibit self-induced resonant voltage steps (SIRS’s), and hence to radiate coherently when placed in a suitable resonant electromagnetic cavity. We analyze this possibility using equations of motion developed to describe such SIRS’s in stacks of artificial Josephson junctions. We conclude that such steps might be observable with a suitably chosen cavity and resonant frequency.

  1. Theory of High-T{sub c} Superconducting Cuprates Based on Experimental Evidence

    DOE R&D Accomplishments Database

    Abrikosov, A. A.

    1999-12-10

    A model of superconductivity in layered high-temperature superconducting cuprates is proposed, based on the extended saddle point singularities in the electron spectrum, weak screening of the Coulomb interaction and phonon-mediated interaction between electrons plus a small short-range repulsion of Hund's, or spin-fluctuation, origin. This permits to explain the large values of T{sub c}, features of the isotope effect on oxygen and copper, the existence of two types of the order parameter, the peak in the inelastic neutron scattering, the positive curvature of the upper critical field, as function of temperature etc.

  2. Theory of high-T{sub c} cuprates based on experimental evidence.

    SciTech Connect

    Abrikosov, A. A.

    1999-08-17

    A model of superconductivity in layered high-temperature superconducting cuprates is proposed, based on the extended saddle point singularities in the electron spectrum, weak screening of the Coulomb interaction and phonon-mediated interaction between electrons plus a small short-range repulsion of Hund's, or spin-fluctuation, origin. This permits to explain the large values of T{sub c}, features of the isotope effect on oxygen and copper, the existence of two types of the order parameter, the peak in the inelastic neutron scattering, the positive curvature of the upper critical field, as function of temperature etc.

  3. Short range smectic order driving long range nematic order: example of cuprates

    PubMed Central

    Markiewicz, R. S.; Lorenzana, J.; Seibold, G.; Bansil, A.

    2016-01-01

    We present a model for describing the combined presence of nematic and ‘smectic’ or stripe-like orders seen in recent scanning tunneling microscopy (STM) experiments on cuprates. The smectic order is treated as an electronic charge density wave with an associated Peierls distortion or a ‘Pomeranchuk wave’. This primary order is restricted to nanoscale domains by disorder effects, while the secondary coupling to strain generates the nematic order with a considerably longer range. A variety of experimental results are shown to be consistent with our theoretical predictions. PMID:26813579

  4. Rainbow Earth.

    ERIC Educational Resources Information Center

    Arizona State Dept. of Library and Archives, Phoenix.

    The environment is a great concern in the 1990s, and everyone needs to work at maintaining our planet. The 1992 Arizona State Library Reading Program, "Rainbow Earth," provides children with many techniques they can use to help the Earth. This reading program guide provides information on the following: goals, objectives, and evaluation; getting…

  5. Earth Wisdom.

    ERIC Educational Resources Information Center

    Van Matre, Steve

    1985-01-01

    In our human-centered ignorance and arrogance we are rapidly destroying the earth. We must start helping people understand the big picture of ecological concepts. What these concepts mean for our own lives and how we must begin to change our lifestyles in order to live more harmoniously with the earth. (JHZ)

  6. Earth tides

    SciTech Connect

    Harrison, J.C.

    1984-01-01

    Nineteen papers on gravity, tilt, and strain tides are compiled into this volume. Detailed chapters cover the calculation of the tidal forces and of the Earth's response to them, as well as actual observations of earth tides. Partial Contents: On Earth tides. The tidal forces: Tidal Forces. New Computations of the Tide-Generating Potential. Corrected Tables of Tidal Harmonics. The Theory of Tidal Deformations. Body Tides on an Elliptical, Rotating, Elastic and Oceanless Earth, Deformation of the Earth by Surface Loads. Gravimetric Tidal Loading Computed from Integrated Green's Functions. Tidal Friction in the Solid Earth. Loading Tides Versus Body Tides. Lunar Tidal Acceleration from Earth Satellite Orbit Analysis. Observations: gravity. Tidal Gravity in Britain: Tidal Loading and the Spatial Distribution of the Marine Tide. Tidal Loading along a Profile Europe-East Africa-South Asia-Australia and the Pacific Ocean. Detailed Gravity-Tide Spectrum between One and Four Cycles per Day. Observations: tilt and strain. Cavity and Topographic Effects in Tilt and Strain Measurement. Observations of Local Elastic Effects on Earth Tide Tilts and Strains.

  7. Self-optimized superconductivity attainable by interlayer phase separation at cuprate interfaces.

    PubMed

    Misawa, Takahiro; Nomura, Yusuke; Biermann, Silke; Imada, Masatoshi

    2016-07-01

    Stabilizing superconductivity at high temperatures and elucidating its mechanism have long been major challenges of materials research in condensed matter physics. Meanwhile, recent progress in nanostructuring offers unprecedented possibilities for designing novel functionalities. Above all, thin films of cuprate and iron-based high-temperature superconductors exhibit remarkably better superconducting characteristics (for example, higher critical temperatures) than in the bulk, but the underlying mechanism is still not understood. Solving microscopic models suitable for cuprates, we demonstrate that, at an interface between a Mott insulator and an overdoped nonsuperconducting metal, the superconducting amplitude is always pinned at the optimum achieved in the bulk, independently of the carrier concentration in the metal. This is in contrast to the dome-like dependence in bulk superconductors but consistent with the astonishing independence of the critical temperature from the carrier density x observed at the interfaces of La2CuO4 and La2-x Sr x CuO4. Furthermore, we identify a self-organization mechanism as responsible for the pinning at the optimum amplitude: An emergent electronic structure induced by interlayer phase separation eludes bulk phase separation and inhomogeneities that would kill superconductivity in the bulk. Thus, interfaces provide an ideal tool to enhance and stabilize superconductivity. This interfacial example opens up further ways of shaping superconductivity by suppressing competing instabilities, with direct perspectives for designing devices. PMID:27482542

  8. Single reconstructed Fermi surface pocket in an underdoped single-layer cuprate superconductor

    PubMed Central

    Chan, M. K.; Harrison, N.; McDonald, R. D.; Ramshaw, B. J.; Modic, K. A.; Barišić, N.; Greven, M.

    2016-01-01

    The observation of a reconstructed Fermi surface via quantum oscillations in hole-doped cuprates opened a path towards identifying broken symmetry states in the pseudogap regime. However, such an identification has remained inconclusive due to the multi-frequency quantum oscillation spectra and complications accounting for bilayer effects in most studies. We overcome these impediments with high-resolution measurements on the structurally simpler cuprate HgBa2CuO4+δ (Hg1201), which features one CuO2 plane per primitive unit cell. We find only a single oscillatory component with no signatures of magnetic breakdown tunnelling to additional orbits. Therefore, the Fermi surface comprises a single quasi-two-dimensional pocket. Quantitative modelling of these results indicates that a biaxial charge density wave within each CuO2 plane is responsible for the reconstruction and rules out criss-crossed charge stripes between layers as a viable alternative in Hg1201. Lastly, we determine that the characteristic gap between reconstructed pockets is a significant fraction of the pseudogap energy. PMID:27448102

  9. Self-optimized superconductivity attainable by interlayer phase separation at cuprate interfaces

    PubMed Central

    Misawa, Takahiro; Nomura, Yusuke; Biermann, Silke; Imada, Masatoshi

    2016-01-01

    Stabilizing superconductivity at high temperatures and elucidating its mechanism have long been major challenges of materials research in condensed matter physics. Meanwhile, recent progress in nanostructuring offers unprecedented possibilities for designing novel functionalities. Above all, thin films of cuprate and iron-based high-temperature superconductors exhibit remarkably better superconducting characteristics (for example, higher critical temperatures) than in the bulk, but the underlying mechanism is still not understood. Solving microscopic models suitable for cuprates, we demonstrate that, at an interface between a Mott insulator and an overdoped nonsuperconducting metal, the superconducting amplitude is always pinned at the optimum achieved in the bulk, independently of the carrier concentration in the metal. This is in contrast to the dome-like dependence in bulk superconductors but consistent with the astonishing independence of the critical temperature from the carrier density x observed at the interfaces of La2CuO4 and La2−xSrxCuO4. Furthermore, we identify a self-organization mechanism as responsible for the pinning at the optimum amplitude: An emergent electronic structure induced by interlayer phase separation eludes bulk phase separation and inhomogeneities that would kill superconductivity in the bulk. Thus, interfaces provide an ideal tool to enhance and stabilize superconductivity. This interfacial example opens up further ways of shaping superconductivity by suppressing competing instabilities, with direct perspectives for designing devices. PMID:27482542

  10. Single reconstructed Fermi surface pocket in an underdoped single-layer cuprate superconductor.

    PubMed

    Chan, M K; Harrison, N; McDonald, R D; Ramshaw, B J; Modic, K A; Barišić, N; Greven, M

    2016-01-01

    The observation of a reconstructed Fermi surface via quantum oscillations in hole-doped cuprates opened a path towards identifying broken symmetry states in the pseudogap regime. However, such an identification has remained inconclusive due to the multi-frequency quantum oscillation spectra and complications accounting for bilayer effects in most studies. We overcome these impediments with high-resolution measurements on the structurally simpler cuprate HgBa2CuO4+δ (Hg1201), which features one CuO2 plane per primitive unit cell. We find only a single oscillatory component with no signatures of magnetic breakdown tunnelling to additional orbits. Therefore, the Fermi surface comprises a single quasi-two-dimensional pocket. Quantitative modelling of these results indicates that a biaxial charge density wave within each CuO2 plane is responsible for the reconstruction and rules out criss-crossed charge stripes between layers as a viable alternative in Hg1201. Lastly, we determine that the characteristic gap between reconstructed pockets is a significant fraction of the pseudogap energy. PMID:27448102

  11. p-Orbital Density Wave with d Symmetry in High-Tc Cuprate Superconductors

    NASA Astrophysics Data System (ADS)

    Tsuchiizu, Masahisa; Yamakawa, Youichi; Kontani, Hiroshi

    Emergence of the nematic density wave is a fundamental unsolved problem in cuprate superconductors. To understand the origin of the nematicity, we employ the recently-developed functional renormalization-group method with high numerical accuracy, and discover the critical development of the p-orbital-density-wave (p-ODW) instability in the strong-spin-fluctuation region. The obtained p-ODW state possesses the key characteristics of the charge ordering pattern in Bi- and Y-based superconductors, such as the wavevector parallel to the nearest Cu-Cu direction, and the d-symmetry form factor with the antiphase correlation between px and py orbitals in the same unit cell. From the beautiful scaling relation between the spin susceptibility and the p-ODW susceptibility, we conclude that the p-ODW is driven by the strong interference between spin and charge fluctuations. It is clarified that the strong charge-spin interference, which is the origin of the nematicity, is the hidden but significant characteristics of the electronic states in cuprate superconductors.

  12. Quasi-particles ultrafastly releasing kink bosons to form Fermi arcs in a cuprate superconductor

    PubMed Central

    Ishida, Y.; Saitoh, T.; Mochiku, T.; Nakane, T.; Hirata, K.; Shin, S.

    2016-01-01

    In a conventional framework, superconductivity is lost at a critical temperature (Tc) because, at higher temperatures, gluing bosons can no longer bind two electrons into a Cooper pair. In high-Tc cuprates, it is still unknown how superconductivity vanishes at Tc. We provide evidence that the so-called ≲70-meV kink bosons that dress the quasi-particle excitations are playing a key role in the loss of superconductivity in a cuprate. We irradiated a 170-fs laser pulse on Bi2Sr2CaCu2O8+δ and monitored the responses of the superconducting gap and dressed quasi-particles by time- and angle-resolved photoemission spectroscopy. We observe an ultrafast loss of superconducting gap near the d-wave node, or light-induced Fermi arcs, which is accompanied by spectral broadenings and weight redistributions occurring within the kink binding energy. We discuss that the underlying mechanism of the spectral broadening that induce the Fermi arc is the undressing of quasi-particles from the kink bosons. The loss mechanism is beyond the conventional framework, and can accept the unconventional phenomena such as the signatures of Cooper pairs remaining at temperatures above Tc. PMID:26728626

  13. Power-law Optical Conductivity from Unparticles: Application to the Cuprates

    NASA Astrophysics Data System (ADS)

    Limtragool, Kridsanaphong; Phillips, Philip

    We calculate the optical conductivity using several models for unparticle or scale-invariant matter. Within a Gaussian action for unparticles that is gauged with Wilson lines, we find that the conductivity computed from the Kubo formalism with vertex corrections yields no non-trivial deviation from the free-theory result. This result obtains because at the Gaussian level, unparticles are just a superposition of particle fields and hence any transport property must be consistent with free theory. Beyond the Gaussian approach, we adopt the continuous mass formulation of unparticles and calculate the Drude conductivity directly. We show that unparticles in this context can be tailored to yield an algebraic conductivity that scales as ω - 2 / 3 with the associated phase angle between the imaginary and real parts of arctanσ2/σ1 =60° as is seen in the cuprates. Our results indicate that at each frequency in the scaling regime, excitations on all energy scales contribute. Hence, incoherence is at the heart of the power-law in the optical conductivity in strongly correlated systems such as the cuprates. We thank NSF DMR-1461952 for partial funding of this project. KL is supported by a scholarship from the Ministry of Science and Technology, Royal Thai Government. PP thanks the Guggenheim Foundation for a 2015-2016 Fellowship.

  14. Spin-fermion model with overlapping hot spots and charge modulation in cuprates

    NASA Astrophysics Data System (ADS)

    Volkov, Pavel A.; Efetov, Konstantin B.

    We study particle-hole instabilities in the framework of the spin-fermion model. In contrast to previous studies, we assume that adjacent hot spots can overlap due to a shallow dispersion of the electron spectrum in the antinodal region and take the effects of a remnant Coulomb interaction into account. We demonstrate that at sufficiently small values | ɛ (π , 0) - EF | < Γ , where Γ is a characteristic energy of the fermion-fermion interaction due to the paramagnons, the leading particle-hole instability is a d-form factor Fermi surface deformation rather than the charge modulation along the Brillouin zone diagonals. At lower temperatures, we find that the deformed Fermi surface is further unstable to formation of a d-form factor charge density wave (CDW) with a wave vector along one of the Brillouin zone axes. These findings can explain the robustness of this order in hole-doped cuprates. The approximations made are justified by a small parameter that allows one an Eliashberg-like treatment. Comparison with experiments suggests that in many cuprate compounds the prerequisites for the proposed scenario are indeed fulfilled and the results obtained may explain important features of the charge modulations observed recently.

  15. Random field disorder and charge order driven quantum oscillations in cuprates

    NASA Astrophysics Data System (ADS)

    Russo, Antonio; Chakravarty, Sudip

    In the pseudogap regime of the cuprates, charge order breaks a ℤ2 symmetry. Therefore, the interaction of charge order and quenched disorder due to potential scattering, can, in principle, be treated as a random field Ising model. A numerical analysis of the ground state of such a random field Ising model reveals local, glassy dynamics in both 2 D and 3 D . The glassy dynamics are treated as a heat bath which couple to the itinerant electrons, leading to an unusual electronic non-Fermi liquid. If the dynamics are strong enough, the electron spectral function has no quasiparticle peak and the effective mass diverges at the Fermi surface, precluding quantum oscillations. In contrast to charge density, d-density wave order (reflecting staggered circulating currents) does not directly couple to potential disorder, allowing it to support quantum oscillations. At fourth order in Landau theory, there is a term consisting of the square of the d-density wave order parameter, and the square of the charge order. This coupling could induce parasitic charge order, which may be weak enough for the Fermi liquid behavior to remain uncorrupted. Here, we argue that this distinction must be made clear, as one interprets quantum oscillations in cuprates.

  16. Raman and fluorescence characteristics of resonant inelastic X-ray scattering from doped superconducting cuprates

    DOE PAGESBeta

    Huang, H. Y.; Jia, C. J.; Chen, Z. Y.; Wohlfeld, K.; Moritz, B.; Devereaux, T. P.; Wu, W. B.; Okamoto, J.; Lee, W. S.; Hashimoto, M.; et al

    2016-01-22

    Measurements of spin excitations are essential for an understanding of spin-mediated pairing for superconductivity; and resonant inelastic X-ray scattering (RIXS) provides a considerable opportunity to probe high-energy spin excitations. However, whether RIXS correctly measures the collective spin excitations of doped superconducting cuprates remains under debate. Here we demonstrate distinct Raman- and fluorescence-like RIXS excitations of Bi1.5Pb0.6Sr1.54CaCu2O8+δ. Combining photon-energy and momentum dependent RIXS measurements with theoretical calculations using exact diagonalization provides conclusive evidence that the Raman-like RIXS excitations correspond to collective spin excitations, which are magnons in the undoped Mott insulators and evolve into paramagnons in doped superconducting compounds. In contrast,more » the fluorescence-like shifts are due primarily to the continuum of particle-hole excitations in the charge channel. Our results show that under the proper experimental conditions RIXS indeed can be used to probe paramagnons in doped high-Tc cuprate superconductors.« less

  17. Disentangling Cooper-pair formation above the transition temperature from the pseudogap state in the cuprates

    SciTech Connect

    Kondo, Takeshi; Hamaya, Yoichiro; Palczewski, Ari D.; Takeuchi, Tsunehiro; Wen, J. S.; Xu, Z. J.; Gu, Genda; Schmalian, Joerg; Kaminski, Adam

    2010-12-05

    The discovery of the pseudogap in the cuprates created significant excitement as it was believed to be a signature of pairing, in some cases above room temperature. Indeed, a number of experiments detected phase-fluctuating superconductivity above the transition temperature T{sub c}. However, several recent experiments reported that the pseudogap and superconducting state are characterized by different energy scales and probably compete with each other, leaving open the question of whether the pseudogap is caused by pair formation. Here we report the discovery of a spectroscopic signature of pair formation and demonstrate that in a region commonly referred to as the pseudogap, two distinct states coexist: one that is due to pair formation and persists to an intermediate temperature T{sub pair} < T* and a second - the 'proper' pseudogap - characterized by the loss of spectral weight and anomalies in transport properties that extends up to T*. T{sub pair} has a value around 120-150 K even for materials with very different T{sub c} values and it probably sets a limit on the highest attainable T{sub c} in the cuprates

  18. Disentangling Cooper-pair formation above the transition temperature from the pseudogap state in the cuprates

    SciTech Connect

    Kondo, Takeshi; Hamaya, Yoichiro; Palczewski, Ari D.; Takeuchi, Tsunehiro; Wen, J. S.; Xu, Z. J.; Gu, Genda; Schmalian, Jorg; Kaminski, Adam

    2010-12-05

    The discovery of the pseudogap in the cuprates created significant excitement as it was believed to be a signature of pairing, in some cases above room temperature. Indeed, a number of experiments detected phase-fluctuating superconductivity above the transition temperature T{sub c}. However, several recent experiments reported that the pseudogap and superconducting state are characterized by different energy scales, and probably compete with each other, leaving open the question of whether the pseudogap is caused by pair formation. Here we report the discovery of a spectroscopic signature of pair formation and demonstrate that in a region commonly referred to as the pseudogap, two distinct states coexist: one that is due to pair formation and persists to an intermediate temperature T{sub pair}cuprates.

  19. Magnetic proximity effect at the interface between a cuprate superconductor and an oxide spin valve

    NASA Astrophysics Data System (ADS)

    Ovsyannikov, G. A.; Demidov, V. V.; Khaydukov, Yu. N.; Mustafa, L.; Constantinian, K. Y.; Kalabukhov, A. V.; Winkler, D.

    2016-04-01

    A heterostructure that consists of the YBa2Cu3O7-δ cuprate superconductor and the SrRuO3/La0.7Sr0.3MnO3 ruthenate/manganite spin valve is investigated using SQUID magnetometry, ferromagnetic resonance, and neutron reflectometry. It is shown that a magnetic moment is induced due to the magnetic proximity effect in the superconducting part of the heterostructure, while the magnetic moment in the composite ferromagnetic interlayer is suppressed. The magnetization emerging in the superconductor coincides in order of magnitude with the results of calculations taking into account the induced magnetic moment of Cu atoms because of orbital reconstruction at the interface between the superconductor and the ferromagnet, as well as with the results of the model taking into account the variations in the density of states at a distance on the order of the coherence length in the superconductor. The experimentally obtained characteristic penetration depth of the magnetic moment in the superconductor considerably exceeds the coherence length of the cuprate superconductor, which indicates the predominance of the mechanism of induced magnetic moment of Cu atoms.

  20. Nodal bilayer-splitting controlled by spin-orbit interactions in underdoped high-Tc cuprates

    PubMed Central

    Harrison, N.; Ramshaw, B. J.; Shekhter, A.

    2015-01-01

    The highest superconducting transition temperatures in the cuprates are achieved in bilayer and trilayer systems, highlighting the importance of interlayer interactions for high Tc. It has been argued that interlayer hybridization vanishes along the nodal directions by way of a specific pattern of orbital overlap. Recent quantum oscillation measurements in bilayer cuprates have provided evidence for a residual bilayer-splitting at the nodes that is sufficiently small to enable magnetic breakdown tunneling at the nodes. Here we show that several key features of the experimental data can be understood in terms of weak spin-orbit interactions naturally present in bilayer systems, whose primary effect is to cause the magnetic breakdown to be accompanied by a spin flip. These features can now be understood to include the equidistant set of three quantum oscillation frequencies, the asymmetry of the quantum oscillation amplitudes in c-axis transport compared to ab-plane transport, and the anomalous magnetic field angle dependence of the amplitude of the side frequencies suggestive of small effective g-factors. We suggest that spin-orbit interactions in bilayer systems can further affect the structure of the nodal quasiparticle spectrum in the superconducting phase. PACS numbers: 71.45.Lr, 71.20.Ps, 71.18.+y PMID:26039222

  1. Raman and fluorescence characteristics of resonant inelastic X-ray scattering from doped superconducting cuprates

    PubMed Central

    Huang, H. Y.; Jia, C. J.; Chen, Z. Y.; Wohlfeld, K.; Moritz, B.; Devereaux, T. P.; Wu, W. B.; Okamoto, J.; Lee, W. S.; Hashimoto, M.; He, Y.; Shen, Z. X.; Yoshida, Y.; Eisaki, H.; Mou, C. Y.; Chen, C. T.; Huang, D. J.

    2016-01-01

    Measurements of spin excitations are essential for an understanding of spin-mediated pairing for superconductivity; and resonant inelastic X-ray scattering (RIXS) provides a considerable opportunity to probe high-energy spin excitations. However, whether RIXS correctly measures the collective spin excitations of doped superconducting cuprates remains under debate. Here we demonstrate distinct Raman- and fluorescence-like RIXS excitations of Bi1.5Pb0.6Sr1.54CaCu2O8+δ. Combining photon-energy and momentum dependent RIXS measurements with theoretical calculations using exact diagonalization provides conclusive evidence that the Raman-like RIXS excitations correspond to collective spin excitations, which are magnons in the undoped Mott insulators and evolve into paramagnons in doped superconducting compounds. In contrast, the fluorescence-like shifts are due primarily to the continuum of particle-hole excitations in the charge channel. Our results show that under the proper experimental conditions RIXS indeed can be used to probe paramagnons in doped high-Tc cuprate superconductors. PMID:26794437

  2. Emergent non-Fermi liquid in the pseudogap phase of the underdoped cuprates

    NASA Astrophysics Data System (ADS)

    Das, Tanmoy; Markiewicz, R. S.; Bansil, A.

    2010-03-01

    As the cuprates approach the Mott insulator limit, they display a remarkable gossamer-like structure: the near-Fermi level dispersion remains nearly unrenormalized while the corresponding spectral weight tends to vanish at half filling[1]. This unusual behavior cannot be understood by conventional Fermi liquid theory where both features are controlled by a single renormalization factor. We find that while the fluctuation spectrum remains nearly isotropic in cuprates, the competing order pseudogap (here modelled as antiferromagnetism) breaks the crystal symmetry and thus promotes a strong momentum dependence in the self-energy term[2]. At half-filling, this yields an essentially unrenormalized quasiparticle dispersion which approaches the uncorrelated limit, while in sharp contrast the quasiparticle spectral weight renormalizes to zero. These opposing tendencies of dispersion and spectral weight renormalization conspire in such a way that the specific heat remains Fermi liquid like in character at all dopings in accord with experiments. Work supported in part by the USDOE. [1] S. Sahrakorpi, et al., Phys. Rev. B 78, 104513 (2008). [2] T. Das, et al., arXiv:0807.4257.

  3. Exact phase diagram of multi-orbital spin-fermion model for hole doped cuprates

    NASA Astrophysics Data System (ADS)

    Meetei, Oinam Nganba; Fischer, Mark; Lawler, Michael; Paramekanti, Arun; Kim, Eun-Ah

    2015-03-01

    Recent experiments revealing the ubiquitous presence of spin and charge ordered states in hole-doped cuprates have placed the study of broken symmetry states at the center of high Tc superconductivity research. Here we aim to understand the phase diagram of broken symmetry states using a simple model that captures the essence of hole doped cuprates. The model consists of itinerant quantum holes on oxygen p-orbitals coupled to classical Cu spins. It is amenable to sign problem free Monte-Carlo simulation allowing us to study finite temperature properties as well as unbiased determination of ground state spin and charge configuration. As a function of system parameters, we obtain a rich phase diagram. Our analysis provides a transparent and unifying picture for various charge and spin ordered states as arising from frustration of antiferromagnetic order due to hole doping, through exact finite temperature phase diagram of the model. Supported by the U.S. Department of Energy Grant DE-SC0010313.

  4. Emergence of Complex States in CMR Manganites and High-Tc Cuprates

    NASA Astrophysics Data System (ADS)

    Dagotto, Elbio

    2005-03-01

    Recent developments in the context of theory and experiments for manganites and cuprates will be discussed. It will be argued that the presence of nanoscale phase separation is at the heart of the colossal magnetoresistance phenomenon [1]. Simulation results support this view, as well as experimental data. These effects are not limited to manganites, but they may appear in other compounds as well, such as the high-Tc cuprates. New results will be presented in this area, on the phenomenological competition between antiferromagnetism and d-wave superconductivity, suggesting the possibility of ``colossal'' effects in this context [2]. This is compatible with the recent discovery of ``giant proximity effects'' in Cu-oxides [3]. All this suggests that clustered or mixed-phase states could form a new paradigm for the understanding of compounds in condensed matter physics. Work in collaboration with G. Alvarez, M. Mayr, A. Moreo, C. Sen, and I. Sergienko, supported by NSF DMR. [1] A. Moreo et al., Science 283, 2034 (1999); E.D., T. Hotta and A. Moreo, Physics Reports 344,1 (2001); E.D., ``Nanoscale Phase Separation and Colossal Magnetoresistance'', Springer-Verlag, 2002. [2] G. Alvarez et al., cond-mat/0401474, PRB to appear. [3] I. Bozovic et al., Phys. Rev. Lett. 93, 157002 (2004)

  5. The Meissner effect in a strongly underdoped cuprate above its critical temperature.

    PubMed

    Morenzoni, Elvezio; Wojek, Bastian M; Suter, Andreas; Prokscha, Thomas; Logvenov, Gennady; Božović, Ivan

    2011-01-01

    The Meissner effect and associated perfect 'bulk' diamagnetism together with zero resistance and gap opening are characteristic features of the superconducting state. In the pseudogap state of cuprates, unusual diamagnetic signals and anomalous proximity effects have been detected, but a Meissner effect has never been observed. Here we probe the local diamagnetic response in the normal state of an underdoped La(1.94)Sr(0.06)CuO(4) layer (T(c)'≤5 K), which is brought into close contact with two nearly optimally doped La(1.84)Sr(0.16)CuO(4) layers (T(c)≈32 K). We show that the entire 'barrier' layer of thickness, much larger than the typical c axis coherence lengths of cuprates, exhibits a Meissner effect at temperatures above T(c)' but below T(c). The temperature dependence of the effective penetration depth and superfluid density in different layers indicates that superfluidity with long-range phase coherence is induced in the underdoped layer by the proximity to optimally doped layers, but this induced order is sensitive to thermal excitation. PMID:21505428

  6. The Meissner effect in a strongly underdoped cuprate above its critical temperature

    PubMed Central

    Morenzoni, Elvezio; Wojek, Bastian M.; Suter, Andreas; Prokscha, Thomas; Logvenov, Gennady; Božović, Ivan

    2011-01-01

    The Meissner effect and associated perfect 'bulk' diamagnetism together with zero resistance and gap opening are characteristic features of the superconducting state. In the pseudogap state of cuprates, unusual diamagnetic signals and anomalous proximity effects have been detected, but a Meissner effect has never been observed. Here we probe the local diamagnetic response in the normal state of an underdoped La1.94Sr0.06CuO4 layer (Tc′≤5 K), which is brought into close contact with two nearly optimally doped La1.84Sr0.16CuO4 layers (Tc≈32 K). We show that the entire 'barrier' layer of thickness, much larger than the typical c axis coherence lengths of cuprates, exhibits a Meissner effect at temperatures above Tc′ but below Tc. The temperature dependence of the effective penetration depth and superfluid density in different layers indicates that superfluidity with long-range phase coherence is induced in the underdoped layer by the proximity to optimally doped layers, but this induced order is sensitive to thermal excitation. PMID:21505428

  7. Single reconstructed Fermi surface pocket in an underdoped single-layer cuprate superconductor

    NASA Astrophysics Data System (ADS)

    Chan, M. K.; Harrison, N.; McDonald, R. D.; Ramshaw, B. J.; Modic, K. A.; Barišić, N.; Greven, M.

    2016-07-01

    The observation of a reconstructed Fermi surface via quantum oscillations in hole-doped cuprates opened a path towards identifying broken symmetry states in the pseudogap regime. However, such an identification has remained inconclusive due to the multi-frequency quantum oscillation spectra and complications accounting for bilayer effects in most studies. We overcome these impediments with high-resolution measurements on the structurally simpler cuprate HgBa2CuO4+δ (Hg1201), which features one CuO2 plane per primitive unit cell. We find only a single oscillatory component with no signatures of magnetic breakdown tunnelling to additional orbits. Therefore, the Fermi surface comprises a single quasi-two-dimensional pocket. Quantitative modelling of these results indicates that a biaxial charge density wave within each CuO2 plane is responsible for the reconstruction and rules out criss-crossed charge stripes between layers as a viable alternative in Hg1201. Lastly, we determine that the characteristic gap between reconstructed pockets is a significant fraction of the pseudogap energy.

  8. The Meissner effect in a Strongly Underdoped Cuprate Above its Critical Temperature

    SciTech Connect

    Morenzoni, E.; Bozovic, I.; Wojek, B.M.; Suter, A.; Prokscha, T.; Logvenov, G.

    2011-04-01

    The Meissner effect and associated perfect 'bulk' diamagnetism together with zero resistance and gap opening are characteristic features of the superconducting state. In the pseudogap state of cuprates, unusual diamagnetic signals and anomalous proximity effects have been detected, but a Meissner effect has never been observed. Here we probe the local diamagnetic response in the normal state of an underdoped La{sub 1.94}Sr{sub 0.06}CuO{sub 4} layer (T'{sub c} {le} 5 K), which is brought into close contact with two nearly optimally doped La{sub 1.84}Sr{sub 0.16}CuO{sub 4} layers (T{sub c} {approx} 32 K). We show that the entire 'barrier' layer of thickness, much larger than the typical c axis coherence lengths of cuprates, exhibits a Meissner effect at temperatures above T{sub c}' but below T{sub c}. The temperature dependence of the effective penetration depth and superfluid density in different layers indicates that superfluidity with long-range phase coherence is induced in the underdoped layer by the proximity to optimally doped layers, but this induced order is sensitive to thermal excitation.

  9. Possible enhancements of AFM spin-fluctuations in high-TC cuprates

    NASA Astrophysics Data System (ADS)

    Jarlborg, Thomas

    2009-03-01

    Ab-initio band calculations for high-TC cuprates, together with modelling based of a free electron like band, show a strong interaction between anti-ferromagnetic (AFM) spin waves and periodic lattice distortions as for phonons, even though this type of spin-phonon coupling (SPC) is underestimated in calculations using the local density approximation. The SPC has a direct influence on the properties of the HTC cuprates and it can explain many observations. The strongest effects are seen for modulated waves in the CuO bond direction, and a band gap is formed near the X,Y points, but unusal band dispersion (like ``waterfalls'') might also be induced below the Fermi energy (EF) in the diagonal direction. The band results are used to propose different ways of increasing AFM spin-fluctuations locally, and to have a higher density-of-states (DOS) at EF. Static potential modulations, via periodic distribution of dopants or lattice distortions, can be tuned to increase the DOS. This opens for possibilities to enhance coupling for spin fluctuations (λsf) and superconductivity. The exchange enhancement is in general increased near a surface, which suggests a tendency towards static spin configurations. The sensivity of the band results to corrections of the local density potential are discussed.

  10. Nodal bilayer-splitting controlled by spin-orbit interactions in underdoped high-Tc cuprates

    DOE PAGESBeta

    Harrison, N.; Ramshaw, B. J.; Shekhter, A.

    2015-06-03

    The highest superconducting transition temperatures in the cuprates are achieved in bilayer and trilayer systems, highlighting the importance of interlayer interactions for high Tc. It has been argued that interlayer hybridization vanishes along the nodal directions by way of a specific pattern of orbital overlap. Recent quantum oscillation measurements in bilayer cuprates have provided evidence for a residual bilayer-splitting at the nodes that is sufficiently small to enable magnetic breakdown tunneling at the nodes. Here we show that several key features of the experimental data can be understood in terms of weak spin-orbit interactions naturally present in bilayer systems, whosemore » primary effect is to cause the magnetic breakdown to be accompanied by a spin flip. These features can now be understood to include the equidistant set of three quantum oscillation frequencies, the asymmetry of the quantum oscillation amplitudes in c-axis transport compared to ab-plane transport, and the anomalous magnetic field angle dependence of the amplitude of the side frequencies suggestive of small effective g-factors. We suggest that spin-orbit interactions in bilayer systems can further affect the structure of the nodal quasiparticle spectrum in the superconducting phase. PACS numbers: 71.45.Lr, 71.20.Ps, 71.18.+y« less

  11. Origins of large critical temperature variations in single-layer cuprates

    SciTech Connect

    Palczewski, A.D.; Kondo, T.; Khasanov, R.; Kolesikov, N.N.; Timonina; Rotenberg, E.; Ohta, T.; Bendounan, A.; Sassa, Y.; Fedorov, A.; Paihes, S.; Santander-Syro, A.F.; Chang, J.; Shi, M.; Mesot, J.; Fretwell, H.M.; Kaminski, A.

    2008-08-26

    We study the electronic structures of two single-layer superconducting cuprates, Tl{sub 2}Ba{sub 2}CuO{sub 6+{delta}} (Tl2201) and (Bi{sub 1.35}Pb{sub 0.85}) (Sr{sub 1.47}La{sub 0.38}) CuO{sub 6+{delta}} (Bi2201) which have very different maximum critical temperatures (90 K and 35 K, respectively) using angular-resolved photoemission spectroscopy (ARPES). We are able to identify two main differences in their electronic properties. First, the shadow band that is present in double-layer and low T{sub c,max} single-layer cuprates is absent in Tl2201. Recent studies have linked the shadow band to structural distortions in the lattice and the absence of these in Tl2201 may be a contributing factor in its T{sub c,max}. Second, Tl2201's Fermi surface (FS) contains long straight parallel regions near the antinode, while in Bi2201 the antinodal region is much more rounded. Since the size of the superconducting gap is largest in the antinodal region, differences in the band dispersion at the antinode may play a significant role in the pairing and therefore affect the maximum transition temperature.

  12. Raman and fluorescence characteristics of resonant inelastic X-ray scattering from doped superconducting cuprates

    NASA Astrophysics Data System (ADS)

    Huang, H. Y.; Jia, C. J.; Chen, Z. Y.; Wohlfeld, K.; Moritz, B.; Devereaux, T. P.; Wu, W. B.; Okamoto, J.; Lee, W. S.; Hashimoto, M.; He, Y.; Shen, Z. X.; Yoshida, Y.; Eisaki, H.; Mou, C. Y.; Chen, C. T.; Huang, D. J.

    2016-01-01

    Measurements of spin excitations are essential for an understanding of spin-mediated pairing for superconductivity; and resonant inelastic X-ray scattering (RIXS) provides a considerable opportunity to probe high-energy spin excitations. However, whether RIXS correctly measures the collective spin excitations of doped superconducting cuprates remains under debate. Here we demonstrate distinct Raman- and fluorescence-like RIXS excitations of Bi1.5Pb0.6Sr1.54CaCu2O8+δ. Combining photon-energy and momentum dependent RIXS measurements with theoretical calculations using exact diagonalization provides conclusive evidence that the Raman-like RIXS excitations correspond to collective spin excitations, which are magnons in the undoped Mott insulators and evolve into paramagnons in doped superconducting compounds. In contrast, the fluorescence-like shifts are due primarily to the continuum of particle-hole excitations in the charge channel. Our results show that under the proper experimental conditions RIXS indeed can be used to probe paramagnons in doped high-Tc cuprate superconductors.

  13. Substantial T-dependences of the Cu-NMR relaxation rates in the underdoped cuprates

    NASA Astrophysics Data System (ADS)

    Goto, Atsushi; Shimizu, Tadashi

    2001-03-01

    We discuss two distinct effects observed in the spin-spin relaxation process in the planar Cu sites of the underdoped high-Tc cuprates. One originates from the interlayer spin correlations in bi- and tri-layered CuO2 planes [1,2], which introduce relaxation in addition to that of a single CuO2 plane. These processes become more significant at low T, i.e., in the pseudogap T region [2]. The other is from T1 fluctuations of the nuclear spins in the vicinity of the nucleus of interest [3], which change the characteristic of the relaxation process from a static to a dynamical one. We demonstrate the principal roles of these effects in the underdoped cuprate (HgRe)Ba_2Ca_2Cu_3O8 and show that, although the total 1/T_2G increases with decreasing T, its intraplane contribution decreases as T is reduced in the pseudogap region, as does 1/T_1T [4]. [1] J. Kishine, Thesis, Univ. of Tokyo, 1996. [2] A. Goto and T. Shimizu, Phys. Rev. B 57 (1998) 7977. [3] R. E. Walstedt and S-W. Cheong, Phys. Rev. B 51 (1995) 3163. [4] A. Goto et al., Phys. Rev. B 59 (1999) R14169.

  14. Atomic-scale electronic structure of the cuprate d-symmetry form factor density wave state

    NASA Astrophysics Data System (ADS)

    Hamidian, M. H.; Edkins, S. D.; Kim, Chung Koo; Davis, J. C.; MacKenzie, A. P.; Eisaki, H.; Uchida, S.; Lawler, M. J.; Kim, E.-A.; Sachdev, S.; Fujita, K.

    2016-02-01

    Research on high-temperature superconducting cuprates is at present focused on identifying the relationship between the classic `pseudogap’ phenomenon and the more recently investigated density wave state. This state is generally characterized by a wavevector Q parallel to the planar Cu-O-Cu bonds along with a predominantly d-symmetry form factor (dFF-DW). To identify the microscopic mechanism giving rise to this state, one must identify the momentum-space states contributing to the dFF-DW spectral weight, determine their particle-hole phase relationship about the Fermi energy, establish whether they exhibit a characteristic energy gap, and understand the evolution of all these phenomena throughout the phase diagram. Here we use energy-resolved sublattice visualization of electronic structure and reveal that the characteristic energy of the dFF-DW modulations is actually the `pseudogap’ energy Δ1. Moreover, we demonstrate that the dFF-DW modulations at E = -Δ1 (filled states) occur with relative phase π compared to those at E = Δ1 (empty states). Finally, we show that the conventionally defined dFF-DW Q corresponds to scattering between the `hot frontier’ regions of momentum-space beyond which Bogoliubov quasiparticles cease to exist. These data indicate that the cuprate dFF-DW state involves particle-hole interactions focused at the pseudogap energy scale and between the four pairs of `hot frontier’ regions in momentum space where the pseudogap opens.

  15. Phase separation of electrons strongly coupled with phonons in cuprates and manganites

    NASA Astrophysics Data System (ADS)

    Alexandrov, Sasha

    2009-03-01

    Recent advanced Monte Carlo simulations have not found superconductivity and phase separation in the Hubbard model with on-site repulsive electron-electron correlations. I argue that microscopic phase separations in cuprate superconductors and colossal magnetoresistance (CMR) manganites originate from a strong electron-phonon interaction (EPI) combined with unavoidable disorder. Attractive electron correlations, caused by an almost unretarded EPI, are sufficient to overcome the direct inter-site Coulomb repulsion in these charge-transfer Mott-Hubbard insulators, so that low energy physics is that of small polarons and small bipolarons. They form clusters localized by disorder below the mobility edge, but propagate as the Bloch states above the mobility edge. I identify the Froehlich EPI as the most essential for pairing and phase separation in superconducting layered cuprates. The pairing of oxygen holes into heavy bipolarons in the paramagnetic phase (current-carrier density collapse (CCDC)) explains also CMR and high and low-resistance phase coexistence near the ferromagnetic transition of doped manganites.

  16. Electronic structure of hole centers in CuO2 planes of cuprates

    NASA Astrophysics Data System (ADS)

    Moskvin, A. S.; Panov, Yu. D.

    2011-03-01

    A theoretical analysis and a large amount of experimental data indicate that the structure of the valence hole states in doped cuprates is more complicated than assumed in the simple Zhang-Rice singlet model. In fact, we are dealing with a competition between a hybrid Cu3d -O2pb1g∝dx2-y2-state and purely oxygen nonbonding states with a2g- and eux ,y∝px ,y-symmetries. Thus, as a cluster analog of a Cu3+ ion, the ground state of a non-Zhang-Rice CuO45- hole center of this sort should be described by complicated A1g1-B2g1,3-Eu1,3 multiplet with a set of charge, orbital, and spin order parameters, some of which are well known (e.g., spin moment or "ferromagnetic" Ising orbital momentum localized on oxygen ions) while others are unconventional or hidden (e.g., "antiferromagnetic" ordering of Ising orbital momenta localized on four oxygen atoms or a combined spin-orbital-quadrupole ordering). The non-Zhang-Rice CuO45- centers are actually singlet-triplet pseudo-Jahn-Teller centers with strong vibron coupling to the lattice. The complicated structure of the ground-state multiplet of the hole centers shows up in many of the unusual properties of doped cuprates, in particular, their pseudo-gap phase.

  17. Vestigial nematicity from spin and/or charge order in the cuprates

    NASA Astrophysics Data System (ADS)

    Nie, Laimei; Maharaj, Akash; Fradkin, Eduardo; Kivelson, Steven

    Nematic order (C4 rotation symmetry breaking) has manifested itself in a variety of materials in the cuprates family, yet its origin remains debatable, with possible links to lattice, charge, and spin degrees of freedom across different doping regimes. We propose an effective field theory of a layered system with incommensurate, intertwined spin- and charge-density wave (SDW and CDW) orders, each of which consists of two components related by C4 rotations. Using a variational free energy approach, we study the growth of the associated nematicity from partially melting those density waves by either increasing temperature or adding quenched disorder. Under the assumption that the zero-disorder, zero-interaction SDW transition temperature is higher than CDW at small doping (and vice versa for large doping), we find that for the general case with finite disorder and interactions there is a universal nematic transition across the entire doping range, accompanied by SDW and CDW transitions (or strong fluctuations at large enough disorder) at lower temperatures. We also discuss the issues concerning the difference between La-based materials and the other hole-doped cuprates.

  18. η collective mode as A1 g Raman resonance in cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Montiel, X.; Kloss, T.; Pépin, C.; Benhabib, S.; Gallais, Y.; Sacuto, A.

    2016-01-01

    We discuss the possible existence of a spin singlet excitation with charge ±2 (η mode) originating the A1 g Raman resonance in cuprate superconductors. This η mode relates the d -wave superconducting singlet pairing channel to a d -wave charge channel. We show that the η boson forms a particle-particle bound state below the 2 Δ threshold of the particle-hole continuum where Δ is the maximum d -wave gap. Within a generalized random phase approximation and Bethe-Salpeter approximation study, we find that this mode has energies similar to the resonance observed with inelastic neutron scattering below the superconducting (SC) coherent peak at 2 Δ in various SC cuprate compounds. We show that it is a very good candidate for the resonance observed in Raman scattering below the 2 Δ peak in the A1 g symmetry. Since the η mode sits in the S =0 channel, it may be observable via Raman, x-ray, or electron energy loss spectroscopy probes.

  19. Change of carrier density at the pseudogap critical point of a cuprate superconductor.

    PubMed

    Badoux, S; Tabis, W; Laliberté, F; Grissonnanche, G; Vignolle, B; Vignolles, D; Béard, J; Bonn, D A; Hardy, W N; Liang, R; Doiron-Leyraud, N; Taillefer, Louis; Proust, Cyril

    2016-03-10

    The pseudogap is a partial gap in the electronic density of states that opens in the normal (non-superconducting) state of cuprate superconductors and whose origin is a long-standing puzzle. Its connection to the Mott insulator phase at low doping (hole concentration, p) remains ambiguous and its relation to the charge order that reconstructs the Fermi surface at intermediate doping is still unclear. Here we use measurements of the Hall coefficient in magnetic fields up to 88 tesla to show that Fermi-surface reconstruction by charge order in the cuprate YBa2Cu3Oy ends sharply at a critical doping p = 0.16 that is distinctly lower than the pseudogap critical point p* = 0.19 (ref. 11). This shows that the pseudogap and charge order are separate phenomena. We find that the change in carrier density n from n = 1 + p in the conventional metal at high doping (ref. 12) to n = p at low doping (ref. 13) starts at the pseudogap critical point. This shows that the pseudogap and the antiferromagnetic Mott insulator are linked. PMID:26901870

  20. In-plane resistivity anisotropy in underdoped cuprates due to scattering by charge and spin fluctuations

    NASA Astrophysics Data System (ADS)

    Schütt, Michael; Fernandes, Rafael M.

    2015-03-01

    The existence of strong in-plane electronic anisotropies in underdoped cuprates has been reported by a variety of experimental probes, such as transport measurements, scanning tunneling microscopy, and x-ray and neutron scattering. Understanding the origin of these anisotropies and their interplay is fundamental to elucidate the role played by electronic nematicity in the phase diagram of the cuprates. Here we employ a Boltzmann equation approach to investigate the resistivity anisotropy due to scattering by anisotropic spin and charge fluctuations. We show that while spin fluctuations give rise to larger resistivity along the a direction, charge fluctuations promote larger resistivity along the b direction. Because anisotropic charge and spin fluctuations compete, these behaviors give rise to a particular dependence of the resistivity anisotropy with doping, which is consistent with transport experiments performed in YBa2Cu3O7. We discuss the important role played by the CuO chains in YBCO to select the observed type of nematic domains, and propose transport measurements in strained HgBa2CuO4 and Bi2Sr2CaCu2O8 to shed light on the interplay between anisotropic fluctuations and anisotropic resistivity. MS acknowledges the support from the Humboldt Foundation. RMF is supported by the Department of Energy under Award Number DE-SC0012336.

  1. Raman and fluorescence characteristics of resonant inelastic X-ray scattering from doped superconducting cuprates.

    PubMed

    Huang, H Y; Jia, C J; Chen, Z Y; Wohlfeld, K; Moritz, B; Devereaux, T P; Wu, W B; Okamoto, J; Lee, W S; Hashimoto, M; He, Y; Shen, Z X; Yoshida, Y; Eisaki, H; Mou, C Y; Chen, C T; Huang, D J

    2016-01-01

    Measurements of spin excitations are essential for an understanding of spin-mediated pairing for superconductivity; and resonant inelastic X-ray scattering (RIXS) provides a considerable opportunity to probe high-energy spin excitations. However, whether RIXS correctly measures the collective spin excitations of doped superconducting cuprates remains under debate. Here we demonstrate distinct Raman- and fluorescence-like RIXS excitations of Bi1.5Pb0.6Sr1.54CaCu2O(8+δ). Combining photon-energy and momentum dependent RIXS measurements with theoretical calculations using exact diagonalization provides conclusive evidence that the Raman-like RIXS excitations correspond to collective spin excitations, which are magnons in the undoped Mott insulators and evolve into paramagnons in doped superconducting compounds. In contrast, the fluorescence-like shifts are due primarily to the continuum of particle-hole excitations in the charge channel. Our results show that under the proper experimental conditions RIXS indeed can be used to probe paramagnons in doped high-Tc cuprate superconductors. PMID:26794437

  2. Quasi-particles ultrafastly releasing kink bosons to form Fermi arcs in a cuprate superconductor.

    PubMed

    Ishida, Y; Saitoh, T; Mochiku, T; Nakane, T; Hirata, K; Shin, S

    2016-01-01

    In a conventional framework, superconductivity is lost at a critical temperature (Tc) because, at higher temperatures, gluing bosons can no longer bind two electrons into a Cooper pair. In high-Tc cuprates, it is still unknown how superconductivity vanishes at Tc. We provide evidence that the so-called ≲ 70-meV kink bosons that dress the quasi-particle excitations are playing a key role in the loss of superconductivity in a cuprate. We irradiated a 170-fs laser pulse on Bi2Sr2CaCu2O(8+δ) and monitored the responses of the superconducting gap and dressed quasi-particles by time- and angle-resolved photoemission spectroscopy. We observe an ultrafast loss of superconducting gap near the d-wave node, or light-induced Fermi arcs, which is accompanied by spectral broadenings and weight redistributions occurring within the kink binding energy. We discuss that the underlying mechanism of the spectral broadening that induce the Fermi arc is the undressing of quasi-particles from the kink bosons. The loss mechanism is beyond the conventional framework, and can accept the unconventional phenomena such as the signatures of Cooper pairs remaining at temperatures above Tc. PMID:26728626

  3. Random field disorder and charge order driven quantum oscillations in cuprates

    NASA Astrophysics Data System (ADS)

    Russo, Antonio; Chakravarty, Sudip

    2016-03-01

    In the pseudogap regime of the cuprates, a period-2 charge order breaks a Z2 symmetry, reflecting a broken translational symmetry. Therefore, the interaction of charge order and quenched disorder due to potential scattering, can, in principle, be treated as a random field Ising model. A numerical analysis of the ground state of such a random field Ising model reveals local, glassy dynamics in both two and three dimensions. The dynamics are treated in the glassy limit as a heat bath which couples to the itinerant electrons, leading to an unusual electronic non-Fermi-liquid. If the dynamics are strong enough, the electron spectral function has no quasiparticle peak and the effective mass diverges at the Fermi surface, precluding quantum oscillations. In contrast to charge density, d -density wave order (reflecting staggered circulating currents) does not directly couple to potential disorder, allowing it to support quantum oscillations. At fourth order in Landau theory, there is a term consisting of the square of the d -density wave order parameter, and the square of the charge order. This coupling could induce parasitic charge order, which may be weak enough for the Fermi liquid behavior to remain uncorrupted. Here, we argue that this distinction must be made clear, as one interprets quantum oscillations in cuprates.

  4. Ultrasonic signatures at the superconducting and the pseudogap phase boundaries in YBCO cuprates.

    SciTech Connect

    Shehter, Arkady; Migliori, Albert; Betts, Jonathan B.; Balakirev, Fedor F.; McDonald, Ross David; Riggs, Scott C.; Ramshaw, Brad; Liang, Ruixing; Hardy, Walter N.; Bonn, Doug A.

    2012-08-28

    A major issue in the understanding of cuprate superconductors is the nature of the metallic state from which high temperature superconductivity emerges. Central to this issue is the pseudogap region of the doping-temperature phase diagram that extends from room temperature to the superconducting transition. Although polarized neutron scattering studies hint at magnetic order associated with the pseudogap, there is no clear thermodynamic evidence for a phase boundary. Such evidence has a straightforward physical interpretation, however, it is difficult to obtain over a temperature range wide enough to encompass both the pseudogap and superconducting phases. We address this by measuring the elastic response of detwinned single crystals, an underdoped YBCO{sub 6.60} with superconducting transition at T{sub c} = 61.6K and a slightly overdoped YBCO{sub 6.98} with T{sub c} = 88.0K. We observe a discontinuity in the elastic moduli across the superconducting transition. Its magnitude requires that pair formation is coincident with superconducting coherence (the onset of the Meissner effect). For both crystals the elastic response reveals a phase transition at the pseudogap boundary. In slightly overdoped YBCO that transition is 20K below T{sub c}, extending the pseudogap phase boundary inside the superconducting dome. This supports a description of the metallic state in cuprates where a pseudogap phase boundary evolves into a quantum critical point masked by the superconducting dome.

  5. Change of carrier density at the pseudogap critical point of a cuprate superconductor

    NASA Astrophysics Data System (ADS)

    Badoux, S.; Tabis, W.; Laliberté, F.; Grissonnanche, G.; Vignolle, B.; Vignolles, D.; Béard, J.; Bonn, D. A.; Hardy, W. N.; Liang, R.; Doiron-Leyraud, N.; Taillefer, Louis; Proust, Cyril

    2016-03-01

    The pseudogap is a partial gap in the electronic density of states that opens in the normal (non-superconducting) state of cuprate superconductors and whose origin is a long-standing puzzle. Its connection to the Mott insulator phase at low doping (hole concentration, p) remains ambiguous and its relation to the charge order that reconstructs the Fermi surface at intermediate doping is still unclear. Here we use measurements of the Hall coefficient in magnetic fields up to 88 tesla to show that Fermi-surface reconstruction by charge order in the cuprate YBa2Cu3Oy ends sharply at a critical doping p = 0.16 that is distinctly lower than the pseudogap critical point p* = 0.19 (ref. 11). This shows that the pseudogap and charge order are separate phenomena. We find that the change in carrier density n from n = 1 + p in the conventional metal at high doping (ref. 12) to n = p at low doping (ref. 13) starts at the pseudogap critical point. This shows that the pseudogap and the antiferromagnetic Mott insulator are linked.

  6. A simple model for normal state in- and out-of-plane resistivities of hole doped cuprates

    NASA Astrophysics Data System (ADS)

    Naqib, S. H.; Azam, M. Afsana; Uddin, M. Borhan; Cole, J. R.

    2016-05-01

    The highly anisotropic and qualitatively different nature of the normal state in- and out-of-plane charge dynamics in high-Tc cuprates cannot be accommodated within the conventional Boltzmann transport theory. The variation of in-plane and out-of-plane resistivities with temperature and hole content are anomalous and cannot be explained by Fermi-liquid theory. In this study, we have proposed a simple phenomenological model for the dc resistivity of cuprates by incorporating two firmly established generic features of all hole doped cuprate superconductors-(i) the pseudogap in the quasiparticle energy spectrum and (ii) the T-linear resistivity at high temperatures. This T-linear behavior over an extended temperature range can be attributed to a quantum criticality, affecting the electronic phase diagram of cuprates. Experimental in-plane and out-of-plane resistivities (ρp(T) and ρc(T), respectively) of double-layer Y(Ca)123 have been analyzed using the proposed model. This phenomenological model describes the temperature and the hole content dependent resistivity over a wide range of temperature and hole content, p. The characteristic PG energy scale, εg(p), extracted from the analysis of the resistivity data, agrees quite well with those found in variety of other experiments. Various other extracted parameters from the analysis of ρp(T) and ρc(T) data showed systematic trends with changing hole concentration. We have discussed important features found from the analysis in detail in this paper.

  7. Discover Earth

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Discover Earth is a NASA-funded project for teachers of grades 5-12 who want to expand their knowledge of the Earth system, and prepare to become master teachers who promote Earth system science in their own schools, counties, and throughout their state. Participants from the following states are invited to apply: Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, and Washington, DC. Teachers selected for the project participate in a two-week summer workshop conducted at the University of Maryland, College Park; develop classroom-ready materials during the workshop for broad dissemination; conduct a minimum of two peer training activities during the coming school year; and participate in other enrichment/education opportunities as available and desired. Discover Earth is a team effort that utilizes expertise from a range of contributors, and balances science content with hands-on classroom applications.

  8. Discover Earth

    NASA Technical Reports Server (NTRS)

    Steele, Colleen

    1996-01-01

    Discover Earth is a NASA-funded project for teachers of grades 5-12 who want to expand their knowledge of the Earth system, and prepare to become master teachers who promote Earth system science in their own schools, counties, and throughout their state. Participants from the following states are invited to apply: Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, and Washington, DC. Teachers selected for the project participate in a two-week summer workshop conducted at the University of Maryland, College Park; develop classroom-ready materials during the workshop for broad dissemination; conduct a minimum of two peer training activities during the coming school year; and participate in other enrichment/education opportunities as available and desired. Discover Earth is a team effort that utilizes expertise from a range of contributors, and balances science content with hands-on classroom applications.

  9. Earth Rotation

    NASA Technical Reports Server (NTRS)

    Dickey, Jean O.

    1995-01-01

    The study of the Earth's rotation in space (encompassing Universal Time (UT1), length of day, polar motion, and the phenomena of precession and nutation) addresses the complex nature of Earth orientation changes, the mechanisms of excitation of these changes and their geophysical implications in a broad variety of areas. In the absence of internal sources of energy or interactions with astronomical objects, the Earth would move as a rigid body with its various parts (the crust, mantle, inner and outer cores, atmosphere and oceans) rotating together at a constant fixed rate. In reality, the world is considerably more complicated, as is schematically illustrated. The rotation rate of the Earth's crust is not constant, but exhibits complicated fluctuations in speed amounting to several parts in 10(exp 8) [corresponding to a variation of several milliseconds (ms) in the Length Of the Day (LOD) and about one part in 10(exp 6) in the orientation of the rotation axis relative to the solid Earth's axis of figure (polar motion). These changes occur over a broad spectrum of time scales, ranging from hours to centuries and longer, reflecting the fact that they are produced by a wide variety of geophysical and astronomical processes. Geodetic observations of Earth rotation changes thus provide insights into the geophysical processes illustrated, which are often difficult to obtain by other means. In addition, these measurements are required for engineering purposes. Theoretical studies of Earth rotation variations are based on the application of Euler's dynamical equations to the problem of finding the response of slightly deformable solid Earth to variety of surface and internal stresses.

  10. Earth materials and earth dynamics

    SciTech Connect

    Bennett, K; Shankland, T.

    2000-11-01

    In the project ''Earth Materials and Earth Dynamics'' we linked fundamental and exploratory, experimental, theoretical, and computational research programs to shed light on the current and past states of the dynamic Earth. Our objective was to combine different geological, geochemical, geophysical, and materials science analyses with numerical techniques to illuminate active processes in the Earth. These processes include fluid-rock interactions that form and modify the lithosphere, non-linear wave attenuations in rocks that drive plate tectonics and perturb the earth's surface, dynamic recrystallization of olivine that deforms the upper mantle, development of texture in high-pressure olivine polymorphs that create anisotropic velocity regions in the convecting upper mantle and transition zone, and the intense chemical reactions between the mantle and core. We measured physical properties such as texture and nonlinear elasticity, equation of states at simultaneous pressures and temperatures, magnetic spins and bonding, chemical permeability, and thermal-chemical feedback to better characterize earth materials. We artificially generated seismic waves, numerically modeled fluid flow and transport in rock systems and modified polycrystal plasticity theory to interpret measured physical properties and integrate them into our understanding of the Earth. This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

  11. On d+id Density Wave and Superconducting Orderings in Hole-Doped Cuprates

    NASA Astrophysics Data System (ADS)

    Goswami, Partha; Gahlot, Ajay Pratap Singh; Singh, Pankaj

    2013-05-01

    The d+id-density wave (chiral DDW) order, at the anti-ferromagnetic wave vector Q = (π, π), is assumed to represent the pseudo-gap (PG) state of a hole-doped cuprate superconductor. The pairing interaction U(k, k‧) required for d+id ordering comprises of (Ux2-y2(k, k‧), Uxy(k, k‧)), where Ux2-y2(k, k') = U1(cos kxa-cos kya)(cos k'xa- cos k'ya) and Uxy(k, k') = U2sin(kxa)sin(kya) sin(k'xa) sin(k'ya) with U1 > U2. The d-wave superconductivity (DSC), driven by an assumed attractive interaction of the form V(k, k') = -ěrt V1ěrt(cos kxa-cos kya)(cos k'xa- cos k'ya) where V1 is a model parameter, is discussed within the mean-field framework together with the d+id ordering. The single-particle excitation spectrum in the CDDW + DSC state is characterized by the Bogoluibov quasi-particle bands — a characteristic feature of SC state. The coupled gap equations are solved self-consistently together with the equation to determine the chemical potential (μ). With the pinning of the van Hove-singularities close to μ, one is able to calculate the thermodynamic and transport properties of the under-doped cuprates in a consistent manner. The electron specific heat displays non-Fermi liquid feature in the CDDW state. The CDDW and DSC are found to represent two competing orders as the former brings about a depletion of the spectral weight (and Raman response function density) available for pairing in the anti-nodal region of momentum space. It is also shown that the depletion of the spectral weight below Tc at energies larger than the gap amplitude occurs. This is an indication of the strong-coupling superconductivity in cuprates. The calculation of the ratio of the quasi-particle thermal conductivity αxx and temperature in the superconducting phase is found to be constant in the limit of near-zero quasi-particle scattering rate.

  12. Earth: Earth Science and Health

    NASA Technical Reports Server (NTRS)

    Maynard, Nancy G.

    2001-01-01

    A major new NASA initiative on environmental change and health has been established to promote the application of Earth science remote sensing data, information, observations, and technologies to issues of human health. NASA's Earth Sciences suite of Earth observing instruments are now providing improved observations science, data, and advanced technologies about the Earth's land, atmosphere, and oceans. These new space-based resources are being combined with other agency and university resources, data integration and fusion technologies, geographic information systems (GIS), and the spectrum of tools available from the public health community, making it possible to better understand how the environment and climate are linked to specific diseases, to improve outbreak prediction, and to minimize disease risk. This presentation is an overview of NASA's tools, capabilities, and research advances in this initiative.

  13. Physics of {pi}-meson condensation and high temperature cuprate superconductors

    SciTech Connect

    Sushkov, O. P.

    2009-08-15

    The idea of condensation of the Goldstone {pi}-meson field in nuclear matter had been put forward a long time ago. However, it was established that the normal nuclear density is too low, it is not sufficient to condensate {pi} mesons. This is why the {pi} condensation has never been observed. Recent experimental and theoretical studies of high-temperature cuprate superconductors have revealed condensation of Goldstone magnons, the effect fully analogous to the {pi} condensation. The magnon condensation has been observed. It is clear now that quantum fluctuations play a crucial role in the condensation, in particular they drive a quantum phase transition that destroys the condensate at some density of fermions.

  14. Formation of Gapless Fermi Arcs and Fingerprints of Order in the Pseudogap State of Cuprate Superconductors

    SciTech Connect

    Kondo, Takeshi; Palczewski, Ari D.; Hamaya, Yoichiro; Takeuchi, Tsunehiro; Wen, J. S.; Gu, Genda; Kaminski, Adam

    2013-10-11

    We use angle-resolved photoemission spectroscopy and a new quantitative approach based on the partial density of states to study properties of seemingly disconnected portions of the Fermi surface (FS) that are present in the pseudogap state of cuprates called Fermi arcs. We find that the normal state FS collapses very abruptly into Fermi arcs at the pseudogap temperature (T∗). Surprisingly, the length of the Fermi arcs remains constant over an extended temperature range between T∗ and Tpair, consistent with the presence of an ordered state below T∗. These arcs collapse again at the temperature below which pair formation occurs (Tpair) either to a point or a very short arc, whose length is limited by our experimental resolution. The tips of the arcs span between points defining a set of wave vectors in momentum space, which are the fingerprints of the ordered state that causes the pseudogap.

  15. Formation of Gapless Fermi Arcs and Fingerprints of Order in the Pseudogap State of Cuprate Superconductors

    SciTech Connect

    Kondo, Takeshi; Palczewski, Ari; Hamaya, Yoichiro; Takeuchi, Tsunehiro; Wen, J. S.; Xu, Z. J.; Gu, Genda; Kaminski, Adam

    2013-10-08

    We use angle-resolved photoemission spectroscopy and a new quantitative approach based on the partial density of states to study properties of seemingly disconnected portions of the Fermi surface (FS) that are present in the pseudogap state of cuprates called Fermi arcs. We find that the normal state FS collapses very abruptly into Fermi arcs at the pseudogap temperature (T*). Surprisingly, the length of the Fermi arcs remains constant over an extended temperature range between (T*) and Tpair, consistent with the presence of an ordered state below T*. These arcs collapse again at the temperature below which pair formation occurs (Tpair) either to a point or a very short arc, whose length is limited by our experimental resolution. The tips of the arcs span between points defining a set of wave vectors in momentum space, which are the fingerprints of the ordered state that causes the pseudogap.

  16. High-energy anomalies in covalent high-Tc cuprates with large Hubbard Ud on copper

    NASA Astrophysics Data System (ADS)

    Barišić, O. S.; Barišić, S.

    2015-03-01

    A large Ud theory is constructed for the metallic state of high-Tc cuprates. The Emery three-band model, extended with Ox-Oy hopping tpp, and with Ud → ∞, is mapped on slave fermions. The Dyson time-dependent diagrammatic theory in terms of the Cu-O hopping tpd, starting from the nondegenerate unperturbed ground state, is translationally and asymptotically locally gauge invariant. The small parameter of the theory is the average hole occupation of Cu sites nd. The lowest order of the theory generates the single particle propagators of the hybridized pdp- and dpd-fermions with the exact covalent three band structure. The leading many-body effect is band narrowing, accompanied by Landau-like damping of the single particle propagation, due to incoherent local charge Cu-O fluctuations. The corresponding continuum is found below and above the Fermi level.

  17. Role of Lattice Coupling in Establishing Electronic and Magnetic Properties in Quasi-One-Dimensional Cuprates

    NASA Astrophysics Data System (ADS)

    Lee, W. S.; Johnston, S.; Moritz, B.; Lee, J.; Yi, M.; Zhou, K. J.; Schmitt, T.; Patthey, L.; Strocov, V.; Kudo, K.; Koike, Y.; van den Brink, J.; Devereaux, T. P.; Shen, Z. X.

    2013-06-01

    High resolution resonant inelastic x-ray scattering has been performed to reveal the role of lattice coupling in a family of quasi-1D insulating cuprates, Ca2+5xY2-5xCu5O10. Site-dependent low-energy excitations arising from progressive emissions of a 70 meV lattice vibrational mode are resolved for the first time, providing a direct measurement of electron-lattice coupling strength. We show that such electron-lattice coupling causes doping-dependent distortions of the Cu-O-Cu bond angle, which sets the intrachain spin exchange interactions. Our results indicate that the lattice degrees of freedom are fully integrated into the electronic behavior in low-dimensional systems.

  18. Universality class of the structural phase transition in the normal phase of cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Najafi, M. N.; Tavana, A.

    2016-08-01

    The tetragonal-orthorhombic structural phase transition of oxygen atoms in the basal plane of YBa2Cu3O6 +δ high-TC cuprate superconductors is studied numerically. By mapping the system onto the asymmetric next-nearest-neighbor Ising model, we characterize this phase transition. Results indicate the degrees of critical behavior. We show that this phase transition occurs at the temperature TC≃0.148 eV in the thermodynamic limit. By analyzing the critical exponents, it is found that this universality class displays some common features, with the two-dimensional three-state Potts model universality class, although the possibility of other universality classes cannot be ruled out. Conformal invariance at T =Tc is investigated using the Schramm-Loewner evolution (SLE) technique, and it is found that the SLE diffusivity parameter for this system is 3.34 ±0.01 .

  19. Fully consistent theory of response functions in the cuprate pseudogap phase: Implementing the Ward Takahashi identity

    NASA Astrophysics Data System (ADS)

    Wu, Chien-Te; Boyack, Rufus; Scherpelz, Peter; Levin, Kathryn

    2015-03-01

    There is a multiplicity of pairing-based theories of the cuprate pseudogap associated with Fermi surface reconstruction or charge ordering, which have a simple mean-field-like self energy. These include the scenario of Yang, Rice and Zhang and the recent Amperean pairing scenario of Lee. We demonstrate here how to arrive at precise response functions for this class of theories which include vertex corrections, where necessary. Thus one can address two body physics experiments at the same level of accuracy that one addresses the one body physics of photoemission spectroscopy. We do so by exploiting the Ward Takahashi identity. As an illustration, we present the spin dynamical response functions of neutron scattering for three different scenarios, finding that a recently proposed pair Amperean pairing scheme is readily distinguishable from other related scenarios. This work is supported by NSF-MRSEC Grant 0820054.

  20. Weak phase stiffness and nature of the quantum critical point in underdoped cuprates

    SciTech Connect

    Yildirim, Yucel; Ku, Wei

    2015-11-02

    We demonstrate that the zero-temperature superconducting phase diagram of underdoped cuprates can be quantitatively understood in the strong binding limit, using only the experimental spectral function of the “normal” pseudogap phase without any free parameter. In the prototypical (La1–xSrx)2CuO4, a kinetics-driven d-wave superconductivity is obtained above the critical doping δc ~ 5.2%, below which complete loss of superfluidity results from local quantum fluctuation involving local p-wave pairs. Near the critical doping, an enormous mass enhancement of the local pairs is found responsible for the observed rapid decrease of phase stiffness. Lastly, a striking mass divergence is predicted at δc that dictates the occurrence of the observed quantum critical point and the abrupt suppression of the Nernst effects in the nearby region.

  1. Coexistence of Midgap Antiferromagnetic and Mott States in Undoped, Hole- and Electron-Doped Ambipolar Cuprates.

    PubMed

    Yin, Xinmao; Zeng, Shengwei; Das, Tanmoy; Baskaran, G; Asmara, Teguh Citra; Santoso, Iman; Yu, Xiaojiang; Diao, Caozheng; Yang, Ping; Breese, Mark B H; Venkatesan, T; Lin, Hsin; Ariando; Rusydi, Andrivo

    2016-05-13

    We report the first observation of the coexistence of a distinct midgap state and a Mott state in undoped and their evolution in electron and hole-doped ambipolar Y_{0.38}La_{0.62}(Ba_{0.82}La_{0.18})_{2}Cu_{3}O_{y} films using spectroscopic ellipsometry and x-ray absorption spectroscopies at the O K and Cu L_{3,2} edges. Supported by theoretical calculations, the midgap state is shown to originate from antiferromagnetic correlation. Surprisingly, while the magnetic state collapses and its correlation strength weakens with dopings, the Mott state in contrast moves toward a higher energy and its correlation strength increases. Our result provides important clues to the mechanism of electronic correlation strengths and superconductivity in cuprates. PMID:27232036

  2. Inequivalence of single-particle and population lifetimes in a cuprate superconductor

    SciTech Connect

    Yang, Shuolong; Sobota, J. A.; Leuenberger, D.; He, Y.; Hashimoto, M.; Lu, D. H.; Eisaki, H.; Kirchmann, P. S.; Shen, Z. -X.

    2015-06-15

    We study optimally doped Bi-2212 (Tc=96 K) using femtosecond time- and angle-resolved photoelectron spectroscopy. Energy-resolved population lifetimes are extracted and compared with single-particle lifetimes measured by equilibrium photoemission. The population lifetimes deviate from the single-particle lifetimes in the low excitation limit by 1–2 orders of magnitude. Fundamental considerations of electron scattering unveil that these two lifetimes are in general distinct, yet for systems with only electron-phonon scattering they should converge in the low-temperature, low-fluence limit. As a result, the qualitative disparity in our data, even in this limit, suggests that scattering channels beyond electron-phonon interactions play a significant role in the electron dynamics of cuprate superconductors.

  3. Thermal transport in the cuprates: Changes with doping across the phase diagram

    SciTech Connect

    Cohn, J.L.

    1996-12-31

    An overview of recent developments in the understanding of thermal conduction in the cuprates is presented. Anomalous phonon damping underlies an unusual temperature dependence of the in-plane thermal conductivity ({kappa}{sub ab}) for the insulating phases of some materials. This damping is sensitive to light oxygen doping in YBa{sub 2}Cu{sub 3}O{sub 6+x} (YBCO), is possibly related to local structural distortions, and may persist in superconducting compositions. New systematics for the superconducting-state enhancement of {kappa}{sub ab} are discussed. For YBCO the oxygen-doping dependence of the enhancement correlates with that of the pair density as determined by specific heat jumps. The large enhancements observed for fully-oxygenated specimens are attributed to pair condensation on the CuO chains. The implications of this finding and its possible connection with the emergence of the normal-state pseudogap are examined.

  4. Coexistence of Midgap Antiferromagnetic and Mott States in Undoped, Hole- and Electron-Doped Ambipolar Cuprates

    NASA Astrophysics Data System (ADS)

    Yin, Xinmao; Zeng, Shengwei; Das, Tanmoy; Baskaran, G.; Asmara, Teguh Citra; Santoso, Iman; Yu, Xiaojiang; Diao, Caozheng; Yang, Ping; Breese, Mark B. H.; Venkatesan, T.; Lin, Hsin; Ariando; Rusydi, Andrivo

    2016-05-01

    We report the first observation of the coexistence of a distinct midgap state and a Mott state in undoped and their evolution in electron and hole-doped ambipolar Y0.38 La0.62 (Ba0.82 La0.18 )2Cu3 Oy films using spectroscopic ellipsometry and x-ray absorption spectroscopies at the O K and Cu L3 ,2 edges. Supported by theoretical calculations, the midgap state is shown to originate from antiferromagnetic correlation. Surprisingly, while the magnetic state collapses and its correlation strength weakens with dopings, the Mott state in contrast moves toward a higher energy and its correlation strength increases. Our result provides important clues to the mechanism of electronic correlation strengths and superconductivity in cuprates.

  5. Fluctuating charge order in the cuprates: Spatial anisotropy and feedback from superconductivity

    NASA Astrophysics Data System (ADS)

    Wang, Yuxuan; Chowdhury, Debanjan; Chubukov, Andrey V.

    2015-10-01

    We analyze the form of static charge susceptibility χ (q ) in underdoped cuprates near axial momenta (Q ,0 ) and (0 ,Q ) at which short-range static charge order has been observed. We show that the momentum dependence of χ (q ) is anisotropic, and the correlation length in the longitudinal direction is larger than in the transverse direction. We show that correlation lengths in both directions decrease once the system evolves into a superconductor, as a result of the competition between superconductivity and charge order. These results are in agreement with resonant x-ray scattering data [R. Comin et al., Science 347, 1335 (2015), 10.1126/science.1258399]. We also argue that density and current components of the charge order parameter are affected differently by superconductivity: the charge density component is reduced less than the current component and hence extends deeper into the superconducting state. This gives rise to two distinct charge order transitions at zero temperature.

  6. Weak phase stiffness and nature of the quantum critical point in underdoped cuprates

    DOE PAGESBeta

    Yildirim, Yucel; Ku, Wei

    2015-11-02

    We demonstrate that the zero-temperature superconducting phase diagram of underdoped cuprates can be quantitatively understood in the strong binding limit, using only the experimental spectral function of the “normal” pseudogap phase without any free parameter. In the prototypical (La1–xSrx)2CuO4, a kinetics-driven d-wave superconductivity is obtained above the critical doping δc ~ 5.2%, below which complete loss of superfluidity results from local quantum fluctuation involving local p-wave pairs. Near the critical doping, an enormous mass enhancement of the local pairs is found responsible for the observed rapid decrease of phase stiffness. Lastly, a striking mass divergence is predicted at δc thatmore » dictates the occurrence of the observed quantum critical point and the abrupt suppression of the Nernst effects in the nearby region.« less

  7. Tunneling evidence of strong cooper-pair-breaking near T c in cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Wolf, E. L.; Tao, H. J.; Susla, B.

    1991-02-01

    The superconductive tunneling density of states obtained from conventional metal film-insulator tunnel junctions on cleaved (ab) basal planes of single crystal Bi 2Sr 2CaCu 2O 8+y (2212) reveals a rising pair breaking rate Γ(T) near T c, as predicted by Lee and Read. We obtain Γ(T)=2.3 kT c(T/T c) 3, which confirms a recent calculation by Coffey and also recent tunneling results of Takada et al on YBa 2Cu 3O 6. This implies a pair lifetime at T c of about 40 fs in 2212. The results indicate that the T 3 pairbreaking near T c is an intrinsic feature of superconductivity in the cuprate planes.

  8. Electronic polymers and soft-matter-like broken symmetries in underdoped cuprates

    PubMed Central

    Capati, M.; Caprara, S.; Di Castro, C.; Grilli, M.; Seibold, G.; Lorenzana, J.

    2015-01-01

    Empirical evidence in heavy fermion, pnictide and other systems suggests that unconventional superconductivity appears associated to some form of real-space electronic order. For the cuprates, despite several proposals, the emergence of order in the phase diagram between the commensurate antiferromagnetic state and the superconducting state is not well understood. Here we show that in this regime doped holes assemble in ‘electronic polymers'. Within a Monte Carlo study, we find that in clean systems by lowering the temperature the polymer melt condenses first in a smectic state and then in a Wigner crystal both with the addition of inversion symmetry breaking. Disorder blurs the positional order leaving a robust inversion symmetry breaking and a nematic order, accompanied by vector chiral spin order and with the persistence of a thermodynamic transition. Such electronic phases, whose properties are reminiscent of soft-matter physics, produce charge and spin responses in good accord with experiments. PMID:26144868

  9. Doping Dependent Charge Transfer Gap and Realistic Electronic Model of n-type Cuprate Superconductors

    SciTech Connect

    Xiang, T.

    2010-05-03

    Based on the analysis of the measurement data of angle-resolved photoemission spectroscopy (ARPES) and optics, we show that the charge transfer gap is significantly smaller than the optical one and is reduced by doping in electron doped cuprate superconductors. This leads to a strong charge fluctuation between the Zhang-Rice singlet and the upper Hubbard bands. The basic model for describing this system is a hybridized two-band t-J model. In the symmetric limit where the corresponding intra- and inter-band hopping integrals are equal to each other, this two-band model is equivalent to the Hubbard model with an antiferromagnetic exchange interaction (i.e. the t-U-J model). The mean-field result of the t-U-J model gives a good account for the doping evolution of the Fermi surface and the staggered magnetization.

  10. Hall effect and Fermi surface reconstruction via electron pockets in the high-Tc cuprates

    NASA Astrophysics Data System (ADS)

    Storey, J. G.

    2016-01-01

    The mechanism by which the Fermi surface of high-T c cuprates undergoes a dramatic change from a large hole-like barrel to small arcs or pockets on entering the pseudogap phase remains a question of fundamental importance. Here we calculate the normal-state Hall coefficient from the resonating-valence-bond spin-liquid model developed by Yang, Rice and Zhang. In this model, reconstruction of the Fermi surface occurs via an intermediate regime where the Fermi surface consists of both hole- and electron-like pockets. We find that the doping (x) dependence of the Hall number transitions from 1+x to (x) over this narrow doping range. At low temperatures, a switch from a downturn to an upturn in the Hall coefficient signals the departure of the electron-like pockets from the Fermi surface.

  11. Tracking Cooper pairs in a cuprate superconductor by ultrafast angle-resolved photoemission.

    PubMed

    Smallwood, Christopher L; Hinton, James P; Jozwiak, Christopher; Zhang, Wentao; Koralek, Jake D; Eisaki, Hiroshi; Lee, Dung-Hai; Orenstein, Joseph; Lanzara, Alessandra

    2012-06-01

    In high-temperature superconductivity, the process that leads to the formation of Cooper pairs, the fundamental charge carriers in any superconductor, remains mysterious. We used a femtosecond laser pump pulse to perturb superconducting Bi(2)Sr(2)CaCu(2)O(8+δ) and studied subsequent dynamics using time- and angle-resolved photoemission and infrared reflectivity probes. Gap and quasiparticle population dynamics revealed marked dependencies on both excitation density and crystal momentum. Close to the d-wave nodes, the superconducting gap was sensitive to the pump intensity, and Cooper pairs recombined slowly. Far from the nodes, pumping affected the gap only weakly, and recombination processes were faster. These results demonstrate a new window into the dynamical processes that govern quasiparticle recombination and gap formation in cuprates. PMID:22654053

  12. Mutual synchronization of two stacks of intrinsic Josephson junctions in cuprate superconductors

    SciTech Connect

    Lin, Shi-Zeng

    2014-05-07

    Certain high-T{sub c} cuprate superconductors, which naturally realize a stack of Josephson junctions, thus can be used to generate electromagnetic waves in the terahertz region. A plate-like single crystal with 10{sup 4} junctions without cavity resonance was proposed to achieve strong radiation. For this purpose, it is required to synchronize the Josephson plasma oscillation in all junctions. In this work, we propose to use two stacks of junctions shunted in parallel to achieve synchronization. The two stacks are mutually synchronized in the whole IV curve, and there is a phase shift between the plasma oscillation in the two stacks. The phase shift is nonzero when the number of junctions in different stacks is the same, while it can be arbitrary when the number of junctions is different. This phase shift can be tuned continuously by applying a magnetic field when all the junctions are connected by superconducting wires.

  13. Effective single-band Hubbard model for the cuprates: Coulomb interactions and apical oxygen

    NASA Astrophysics Data System (ADS)

    Feiner, L. F.; Jefferson, J. H.; Raimondi, R.

    1995-02-01

    Starting with the three-band d-p model representing the high- Tc cuprates, we make a systematic reduction to an effective single-band model using a previously developed cell-perturbation method. In particular, we consider the effect of Coulomb repulsions on oxygen ( Up) and between copper and oxygen ( Vpd), and show that the resulting net Coloumb interaction between doped holes on neighbouring cells can be attractive due to locally enhanced pd hybridization, while this cannot occur for electrons. Extending to a five-band model, by including d 3 z2- r2 and apex p z orbitals, we show that there is, in addition to the usual Zhang-Rice singlet, a two-hole cell state which can be low in energy (depending on the proximity of the apicals), and may lead to a breakdown of the effective single-band model.

  14. Giant phonon anomaly associated with superconducting fluctuations in the pseudogap phase of cuprates

    DOE PAGESBeta

    Liu, Ye-Hua; Konik, Robert M.; Rice, T. M.; Zhang, Fu-Chun

    2016-01-20

    The pseudogap in underdoped cuprates leads to significant changes in the electronic structure, and was later found to be accompanied by anomalous fluctuations of superconductivity and certain lattice phonons. Here we propose that the Fermi surface breakup due to the pseudogap, leads to a breakup of the pairing order into two weakly coupled sub-band amplitudes, and a concomitant low energy Leggett mode due to phase fluctuations between them. This increases the temperature range of superconducting fluctuations containing an overdamped Leggett mode. In this range inter-sub-band phonons show strong damping due to resonant scattering into an intermediate state with a pairmore » of overdamped Leggett modes. In the ordered state, the Leggett mode develops a finite energy, changing the anomalous phonon damping into an anomaly in the dispersion. Finally, this proposal explains the intrinsic connection between the anomalous pseudogap phase, enhanced superconducting fluctuations and giant anomalies in the phonon spectra.« less

  15. Scaling relation for the superfluid density of cuprate superconductors: Origins and limits

    NASA Astrophysics Data System (ADS)

    Tallon, J. L.; Cooper, J. R.; Naqib, S. H.; Loram, J. W.

    2006-05-01

    A universal scaling relation, ρs∝σ(Tc)×Tc has been reported by Homes [Nature (London) 430, 539 (2004)] where ρs is the superfluid density and σ(T) is the dc conductivity. The relation was shown to apply to both c -axis and in-plane dynamics for high- Tc superconductors as well as to the more conventional superconductors Nb and Pb, suggesting common physics in these systems. We show quantitatively that the scaling behavior has several possible origins, including marginal Fermi-liquid behavior, Josephson coupling, dirty-limit superconductivity, and unitary impurity scattering for a d -wave order parameter. However, the relation breaks down seriously in overdoped cuprates, and possibly even at lower doping.

  16. Angular fluctuations of a multi-component order describe the pseudogap regime of the cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Sachdev, Subir

    2014-03-01

    The hole-doped cuprate high temperature superconductors enter the pseudogap regime as their superconducting critical temperature, Tc, falls with decreasing hole density. Experiments have probed this regime for over two decades, but we argue that decisive new information has emerged from recent X-ray scattering experiments. The experiments observe incommensurate charge density wave fluctuations whose strength rises gradually over a wide temperature range above Tc, but then decreases as the temperature is lowered below Tc. We propose a theory in which the superconducting and charge-density wave orders exhibit angular fluctuations in a 6-dimensional space. The theory provides a natural quantitative fit to the X-ray data, and is consistent with other observed characteristics of the pseudogap. Results will also be presented on the microscopic origins of these order parameters. Work in collaboration with Lauren Hayward, Roger Melko, David Hawthorn, and Jay Sau.

  17. Andreev nanoprobe of half-metallic CrO2 films using superconducting cuprate tips

    NASA Astrophysics Data System (ADS)

    Turel, C. S.; Guilaran, I. J.; Xiong, P.; Wei, J. Y. T.

    2011-11-01

    Superconducting tips of YBa2Cu3O7-x were used to perform point-contact Andreev reflection spectroscopy on half-metallic CrO2 thin films. At 4.2 K, strong suppression of the d-wave Andreev reflection characteristics was observed, consistent with the high spin polarization of CrO2. Our technique was validated by comparison with data taken on non-magnetic Au films and with data taken by superconducting Pb tips. The point contacts were estimated to be ≲10 nm in size, attesting to their ballistic and microscopic nature. Our results demonstrate the feasibility of using superconducting cuprate tips as spin-sensitive nanoprobes of ferromagnets.

  18. A simple theory for the cuprates: The antiferromagnetic van Hove scenario

    SciTech Connect

    Dagotto, E.; Nazarenko, A.; Moreo, A.

    1995-08-01

    A model of weakly interacting hole quasiparticles is proposed to describe the normal state of the high temperature superconductors. The effect of strong correlations is contained in the dispersion of the holes. Many-body effects induce anomalous quasiparticle flat bands similar to those observed in recent angle-resolved photoemission experiments. A model of weakly interacting hole quasiparticles is proposed to describe the physics of carriers in the cuprates. The model predicts superconductivity in the d{sub x{sup 2}{minus}y{sup 2}} channel, with a typical T{sub c} {approximately} 100K. The concept of {open_quotes}optimal doping{close_quotes} appears naturally in this model, as well as a large ratio 2{Delta}/kT{sub c}{approximately}5.

  19. Inequivalence of Single-Particle and Population Lifetimes in a Cuprate Superconductor.

    PubMed

    Yang, S-L; Sobota, J A; Leuenberger, D; He, Y; Hashimoto, M; Lu, D H; Eisaki, H; Kirchmann, P S; Shen, Z-X

    2015-06-19

    We study optimally doped Bi-2212 (T(c)=96  K) using femtosecond time- and angle-resolved photoelectron spectroscopy. Energy-resolved population lifetimes are extracted and compared with single-particle lifetimes measured by equilibrium photoemission. The population lifetimes deviate from the single-particle lifetimes in the low excitation limit by 1-2 orders of magnitude. Fundamental considerations of electron scattering unveil that these two lifetimes are in general distinct, yet for systems with only electron-phonon scattering they should converge in the low-temperature, low-fluence limit. The qualitative disparity in our data, even in this limit, suggests that scattering channels beyond electron-phonon interactions play a significant role in the electron dynamics of cuprate superconductors. PMID:26196996

  20. Scattering rates and specific heat jumps in high-Tc cuprates

    NASA Astrophysics Data System (ADS)

    Storey, James

    Inspired by recent ARPES and tunneling studies on high-Tc cuprates, we examine the effect of a pair-breaking term in the self-energy on the shape of the electronic specific heat jump. It is found that the observed specific heat jump can be described in terms of a superconducting gap, that persists above the observed Tc, in the presence of a strongly temperature dependent pair-breaking scattering rate. An increase in the scattering rate is found to explain the non-BCS-like suppression of the specific heat jump with magnetic field. A discussion of these results in the context of other properties such as the superfluid density and Raman spectra will also be presented. Supported by the Marsden Fund Council from Government funding, administered by the Royal Society of New Zealand.

  1. Quasistatic magnetoelectric multipoles as order parameter for pseudogap phase in cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Fechner, M.; Fierz, M. J. A.; Thöle, F.; Staub, U.; Spaldin, N. A.

    2016-05-01

    We introduce a mechanism in which coupling between fluctuating spin magnetic dipole moments and polar optical phonons leads to a nonzero ferroic ordering of quasistatic magnetoelectric multipoles. Using first-principles calculations within the LSDA +U method of density functional theory, we calculate the magnitude of the effect for the prototypical cuprate superconductor HgBa2CuO4 . We show that our proposed mechanism is consistent, to our knowledge, with all experimental data for the onset of the pseudogap phase and therefore propose the quasistatic magnetoelectric multipole as a possible pseudogap order parameter. Finally, we show that our mechanism embraces some key aspects of previous theoretical models, in particular the description of the pseudogap phase in terms of orbital currents.

  2. Giant phonon anomaly associated with superconducting fluctuations in the pseudogap phase of cuprates

    PubMed Central

    Liu, Ye-Hua; Konik, Robert M.; Rice, T. M.; Zhang, Fu-Chun

    2016-01-01

    The pseudogap in underdoped cuprates leads to significant changes in the electronic structure, and was later found to be accompanied by anomalous fluctuations of superconductivity and certain lattice phonons. Here we propose that the Fermi surface breakup due to the pseudogap, leads to a breakup of the pairing order into two weakly coupled sub-band amplitudes, and a concomitant low energy Leggett mode due to phase fluctuations between them. This increases the temperature range of superconducting fluctuations containing an overdamped Leggett mode. In this range inter-sub-band phonons show strong damping due to resonant scattering into an intermediate state with a pair of overdamped Leggett modes. In the ordered state, the Leggett mode develops a finite energy, changing the anomalous phonon damping into an anomaly in the dispersion. This proposal explains the intrinsic connection between the anomalous pseudogap phase, enhanced superconducting fluctuations and giant anomalies in the phonon spectra. PMID:26785835

  3. Optical conductivity of single plane cuprate superconductor HgBa2CuO4

    NASA Astrophysics Data System (ADS)

    Lobo, R. P. S. M.; Bontemps, N.; Hwang, J.; Yang, J.; Timusk, T.; Colson, D.; Forget, A.

    2007-03-01

    We investigated the ab-plane infrared and visible spectra of a HgBa2CuO4 single crystal close to optimal doping (Tc= 90 K) from 100 to 40000 cm-1. Data as a function of temperature (down to 30 K) was limited to frequencies below 10000 cm-1. The low frequency scattering rate has a linear frequency dependence. Under 120 K a supplementary small drop below 1000 cm-1 suggests the presence of a pseudogap. This is the same frequency at which the optical conductivity shows a clear loss of spectral weight in the superconducting state. The low frequency effective mass is temperature dependent and increases from 1.5 at room temperature to 2.5 just above Tc. We will compare our results to other single plane cuprates.

  4. Evolution des quasiparticules nodales du cuprate supraconducteur YBa2Cu3Oy en conductivite thermique

    NASA Astrophysics Data System (ADS)

    Rene de Cotret, Samuel

    Ce memoire presente des mesures de conductivite thermique sur les supraconducteurs YBCO et Tl-2201 afin de statuer sur la presence possible d'un point critique quantique (QCP) dans le diagramme de phase de cuprates. Ce point critique quantique serait a l'origine de la reconstruction de la surface de Fermi, d'un large cylindre de trous en de petites poches de trous et d'electrons. La conductivite thermique dans le regime T → 0 permet d'extraire une quantite purement electronique liee aux vitesses de Fermi et du gap, au noeud. Une discontinuite dans cette quantite pourrait signaler la traversee du dopage critique qui reconstruit la surface de Fermi. Plusieurs sondes experimentales distinguent une transition de phase ou un crossover a T* a temperature finie. D'autres sondes mettent en evidence une transition de phase sous l'effet d'un champ magnetique. La presence ou non de cet ordre, a temperature et champ magnetique nul questionne la communaute depuis plusieurs annees. Dans cette etude, nous detectons une variation brusque de kappa0/T a p = 0.18 dans YBCO et a p = 0.20 dans Tl-2201. Ces sauts sont interpretes comme un signe de la transition a temperature nulle et sont en faveur d'un QCP. Le manque de donnees d'un meme materiau a ces dopages ne permet pas de valider hors de tout doute l'existence d'un point critique quantique. Le modele theorique YRZ decrit aussi bien les donnees de conductivite thermique. Des pistes de travaux experimentaux a poursuivre sont proposees pour determiner la presence ou non du QCP de facon franche. Mots-cles : Supraconducteurs, cuprates, conductivite thermique, point critique quantique.

  5. Quenched disorder and vestigial nematicity in the pseudogap regime of the cuprates

    PubMed Central

    Nie, Laimei; Tarjus, Gilles; Kivelson, Steven Allan

    2014-01-01

    The cuprate high-temperature superconductors have been the focus of unprecedentedly intense and sustained study not only because of their high superconducting transition temperatures, but also because they represent the most exquisitely investigated examples of highly correlated electronic materials. In particular, the pseudogap regime of the phase diagram exhibits a variety of mysterious emergent behaviors. In the last few years, evidence from NMR and scanning tunneling microscopy (STM) studies, as well as from a new generation of X-ray scattering experiments, has accumulated, indicating that a general tendency to short-range–correlated incommensurate charge density wave (CDW) order is “intertwined” with the superconductivity in this regime. Additionally, transport, STM, neutron-scattering, and optical experiments have produced evidence—not yet entirely understood—of the existence of an associated pattern of long-range–ordered point-group symmetry breaking with an electron-nematic character. We have carried out a theoretical analysis of the Landau–Ginzburg–Wilson effective field theory of a classical incommensurate CDW in the presence of weak quenched disorder. Although the possibilities of a sharp phase transition and long-range CDW order are precluded in such systems, we show that any discrete symmetry-breaking aspect of the charge order—nematicity in the case of the unidirectional (stripe) CDW we consider explicitly—generically survives up to a nonzero critical disorder strength. Such “vestigial order,” which is subject to unambiguous macroscopic detection, can serve as an avatar of what would be CDW order in the ideal, zero disorder limit. Various recent experiments in the pseudogap regime of the hole-doped cuprates are readily interpreted in light of these results. PMID:24799709

  6. The high temperature superconductivity in cuprates: physics of the pseudogap region

    NASA Astrophysics Data System (ADS)

    Cea, Paolo

    2016-08-01

    We discuss the physics of the high temperature superconductivity in hole doped copper oxide ceramics in the pseudogap region. Starting from an effective reduced Hamiltonian relevant to the dynamics of holes injected into the copper oxide layers proposed in a previous paper, we determine the superconductive condensate wavefunction. We show that the low-lying elementary condensate excitations are analogous to the rotons in superfluid 4He. We argue that the rotons-like excitations account for the specific heat anomaly at the critical temperature. We discuss and compare with experimental observations the London penetration length, the Abrikosov vortices, the upper and lower critical magnetic fields, and the critical current density. We give arguments to explain the origin of the Fermi arcs and Fermi pockets. We investigate the nodal gap in the cuprate superconductors and discuss both the doping and temperature dependence of the nodal gap. We suggest that the nodal gap is responsible for the doping dependence of the so-called nodal Fermi velocity detected in angle resolved photoemission spectroscopy studies. We discuss the thermodynamics of the nodal quasielectron liquid and their role in the low temperature specific heat. We propose that the ubiquitous presence of charge density wave in hole doped cuprate superconductors in the pseudogap region originates from instabilities of the nodal quasielectrons driven by the interaction with the planar CuO2 lattice. We investigate the doping dependence of the charge density wave gap and the competition between charge order and superconductivity. We discuss the effects of external magnetic fields on the charge density wave gap and elucidate the interplay between charge density wave and Abrikosov vortices. Finally, we examine the physics underlying quantum oscillations in the pseudogap region.

  7. Spin-fermion model with overlapping hot spots and charge modulation in cuprates

    NASA Astrophysics Data System (ADS)

    Volkov, Pavel A.; Efetov, Konstantin B.

    2016-02-01

    We study particle-hole instabilities in the framework of the spin-fermion (SF) model. In contrast to previous studies, we assume that adjacent hot spots can overlap due to a shallow dispersion of the electron spectrum in the antinodal region. In addition, we take into account effects of a remnant low energy and momentum Coulomb interaction. We demonstrate that at sufficiently small values |ɛ (π ,0 ) - EF|≲Γ , where EF is the Fermi energy, ɛ (π ,0 ) is the energy in the middle of the Brillouin zone edge, and Γ is a characteristic energy of the fermion-fermion interaction due to the antiferromagnetic fluctuations, the leading particle-hole instability is a d -form factor Fermi surface deformation (the Pomeranchuk instability) rather than the charge modulation along the Brillouin zone diagonals predicted within the standard SF model previously. At lower temperatures, we find that the deformed Fermi surface is further unstable to formation of a d -form factor charge density wave (CDW) with a wave vector along the Cu-O-Cu bonds (axes of the Brillouin zone). We show that the remnant Coulomb interaction enhances the d -form-factor symmetry of the CDW. These findings can explain the robustness of this order in the cuprates. The approximations made in the paper are justified by a small parameter that allows one to implement an Eliashberg-like treatment. Comparison with experiments suggests that in many cuprate compounds the prerequisites for the proposed scenario are indeed fulfilled and the results obtained may explain important features of the charge modulations observed recently.

  8. Specific heat of underdoped cuprate superconductors from a phenomenological layered Boson-Fermion model

    NASA Astrophysics Data System (ADS)

    Salas, P.; Fortes, M.; Solís, M. A.; Sevilla, F. J.

    2016-05-01

    We adapt the Boson-Fermion superconductivity model to include layered systems such as underdoped cuprate superconductors. These systems are represented by an infinite layered structure containing a mixture of paired and unpaired fermions. The former, which stand for the superconducting carriers, are considered as noninteracting zero spin composite-bosons with a linear energy-momentum dispersion relation in the CuO2 planes where superconduction is predominant, coexisting with the unpaired fermions in a pattern of stacked slabs. The inter-slab, penetrable, infinite planes are generated by a Dirac comb potential, while paired and unpaired electrons (or holes) are free to move parallel to the planes. Composite-bosons condense at a critical temperature at which they exhibit a jump in their specific heat. These two values are assumed to be equal to the superconducting critical temperature Tc and the specific heat jump reported for YBa2Cu3O6.80 to fix our model parameters namely, the plane impenetrability and the fraction of superconducting charge carriers. We then calculate the isochoric and isobaric electronic specific heats for temperatures lower than Tc of both, the composite-bosons and the unpaired fermions, which matches the latest experimental curves. From the latter, we extract the linear coefficient (γn) at Tc, as well as the quadratic (αT2) term for low temperatures. We also calculate the lattice specific heat from the ARPES phonon spectrum, and add it to the electronic part, reproducing the experimental total specific heat at and below Tc within a 5% error range, from which the cubic (ßT3) term for low temperatures is obtained. In addition, we show that this model reproduces the cuprates mass anisotropies.

  9. Atomic-scale electronic structure of the cuprate d-symmetry form factor density wave state

    DOE PAGESBeta

    M. H. Hamidian; Kim, Chung Koo; Edkins, S. D.; Davis, J. C.; Mackenzie, A. P.; Eisaki, H.; Uchida, S.; Lawler, M. J.; Kim, E. -A.; Sachdev, S.; et al

    2015-10-26

    Research on high-temperature superconducting cuprates is at present focused on identifying the relationship between the classic ‘pseudogap’ phenomenon1, 2 and the more recently investigated density wave state3–13. This state is generally characterized by a wavevector Q parallel to the planar Cu–O–Cu bonds 4–13 along with a predominantly d-symmetry form factor 14–17 (dFF-DW). To identify the microscopic mechanism giving rise to this state 18–30, one must identify the momentum-space states contributing to the dFF-DW spectral weight, determine their particle–hole phase relationship about the Fermi energy, establish whether they exhibit a characteristic energy gap, and understand the evolution of all these phenomenamore » throughout the phase diagram. Here we use energy-resolved sublattice visualization14 of electronic structure and reveal that the characteristic energy of the dFF-DW modulations is actually the ‘pseudogap’ energy Δ1. Moreover, we demonstrate that the dFF-DW modulations at E = –Δ1 (filled states) occur with relative phase π compared to those at E = Δ1 (empty states). Lastly, we show that the conventionally defined dFF-DW Q corresponds to scattering between the ‘hot frontier’ regions of momentum-space beyond which Bogoliubov quasiparticles cease to exist30–32. These data indicate that the cuprate dFF-DW state involves particle–hole interactions focused at the pseudogap energy scale and between the four pairs of ‘hot frontier’ regions in momentum space where the pseudogap opens.« less

  10. Quenched disorder and vestigial nematicity in the pseudogap regime of the cuprates.

    PubMed

    Nie, Laimei; Tarjus, Gilles; Kivelson, Steven Allan

    2014-06-01

    The cuprate high-temperature superconductors have been the focus of unprecedentedly intense and sustained study not only because of their high superconducting transition temperatures, but also because they represent the most exquisitely investigated examples of highly correlated electronic materials. In particular, the pseudogap regime of the phase diagram exhibits a variety of mysterious emergent behaviors. In the last few years, evidence from NMR and scanning tunneling microscopy (STM) studies, as well as from a new generation of X-ray scattering experiments, has accumulated, indicating that a general tendency to short-range-correlated incommensurate charge density wave (CDW) order is "intertwined" with the superconductivity in this regime. Additionally, transport, STM, neutron-scattering, and optical experiments have produced evidence--not yet entirely understood--of the existence of an associated pattern of long-range-ordered point-group symmetry breaking with an electron-nematic character. We have carried out a theoretical analysis of the Landau-Ginzburg-Wilson effective field theory of a classical incommensurate CDW in the presence of weak quenched disorder. Although the possibilities of a sharp phase transition and long-range CDW order are precluded in such systems, we show that any discrete symmetry-breaking aspect of the charge order--nematicity in the case of the unidirectional (stripe) CDW we consider explicitly--generically survives up to a nonzero critical disorder strength. Such "vestigial order," which is subject to unambiguous macroscopic detection, can serve as an avatar of what would be CDW order in the ideal, zero disorder limit. Various recent experiments in the pseudogap regime of the hole-doped cuprates are readily interpreted in light of these results. PMID:24799709

  11. Atomic-scale electronic structure of the cuprate d-symmetry form factor density wave state

    SciTech Connect

    M. H. Hamidian; Kim, Chung Koo; Edkins, S. D.; Davis, J. C.; Mackenzie, A. P.; Eisaki, H.; Uchida, S.; Lawler, M. J.; Kim, E. -A.; Sachdev, S.; Fujita, K.

    2015-10-26

    Research on high-temperature superconducting cuprates is at present focused on identifying the relationship between the classic ‘pseudogap’ phenomenon1, 2 and the more recently investigated density wave state3–13. This state is generally characterized by a wavevector Q parallel to the planar Cu–O–Cu bonds 4–13 along with a predominantly d-symmetry form factor 14–17 (dFF-DW). To identify the microscopic mechanism giving rise to this state 18–30, one must identify the momentum-space states contributing to the dFF-DW spectral weight, determine their particle–hole phase relationship about the Fermi energy, establish whether they exhibit a characteristic energy gap, and understand the evolution of all these phenomena throughout the phase diagram. Here we use energy-resolved sublattice visualization14 of electronic structure and reveal that the characteristic energy of the dFF-DW modulations is actually the ‘pseudogap’ energy Δ1. Moreover, we demonstrate that the dFF-DW modulations at E = –Δ1 (filled states) occur with relative phase π compared to those at E = Δ1 (empty states). Lastly, we show that the conventionally defined dFF-DW Q corresponds to scattering between the ‘hot frontier’ regions of momentum-space beyond which Bogoliubov quasiparticles cease to exist30–32. These data indicate that the cuprate dFF-DW state involves particle–hole interactions focused at the pseudogap energy scale and between the four pairs of ‘hot frontier’ regions in momentum space where the pseudogap opens.

  12. Reassessment of the electronic state, magnetism, and superconductivity in high-Tc cuprates with the Nd2CuO4 structure

    NASA Astrophysics Data System (ADS)

    Naito, Michio; Krockenberger, Yoshiharu; Ikeda, Ai; Yamamoto, Hideki

    2016-04-01

    The electronic phase diagram of the cuprates remains enigmatic and is still a key ingredient to understand the mechanism of high-Tc superconductivity. It has been believed for a long time that parent compounds of cuprates were universally antiferromagnetic Mott insulators (charge-transfer insulators) and that high-Tc superconductivity would develop upon doping holes or electrons in a Mott-Hubbard insulator ("doped Mott-insulator scenario"). However, our recent discovery of superconductivity in the parent compounds of square-planar cuprates with the Nd2CuO4 (T') structure and the revised electronic phase diagram in T' cuprates urged a serious reassessment to the above scenario. In this review, we present the main results derived from our synthesis and experiments on T' cuprates in the undoped or heavily underdoped regime over 20 years, including material issues and basic physics. The key material issue is how to remove excess oxygen ions at the apical site without introducing oxygen vacancies in the CuO2 planes. In order to put this into practice, the basic knowledge of complex solid-state chemistry in T' cuprates is required, which is also included in this review.

  13. Digital Earth - A sustainable Earth

    NASA Astrophysics Data System (ADS)

    Mahavir

    2014-02-01

    All life, particularly human, cannot be sustainable, unless complimented with shelter, poverty reduction, provision of basic infrastructure and services, equal opportunities and social justice. Yet, in the context of cities, it is believed that they can accommodate more and more people, endlessly, regardless to their carrying capacity and increasing ecological footprint. The 'inclusion', for bringing more and more people in the purview of development is often limited to social and economic inclusion rather than spatial and ecological inclusion. Economic investment decisions are also not always supported with spatial planning decisions. Most planning for a sustainable Earth, be at a level of rural settlement, city, region, national or Global, fail on the capacity and capability fronts. In India, for example, out of some 8,000 towns and cities, Master Plans exist for only about 1,800. A chapter on sustainability or environment is neither statutorily compulsory nor a norm for these Master Plans. Geospatial technologies including Remote Sensing, GIS, Indian National Spatial Data Infrastructure (NSDI), Indian National Urban Information Systems (NUIS), Indian Environmental Information System (ENVIS), and Indian National GIS (NGIS), etc. have potential to map, analyse, visualize and take sustainable developmental decisions based on participatory social, economic and social inclusion. Sustainable Earth, at all scales, is a logical and natural outcome of a digitally mapped, conceived and planned Earth. Digital Earth, in fact, itself offers a platform to dovetail the ecological, social and economic considerations in transforming it into a sustainable Earth.

  14. Earth Algebra.

    ERIC Educational Resources Information Center

    Schaufele, Christopher; Zumoff, Nancy

    Earth Algebra is an entry level college algebra course that incorporates the spirit of the National Council of Teachers of Mathematics (NCTM) Curriculum and Evaluation Standards for School Mathematics at the college level. The context of the course places mathematics at the center of one of the major current concerns of the world. Through…

  15. Earth Flats

    NASA Astrophysics Data System (ADS)

    Bohlin, R. C.; Mack, J.; Hartig, G.; Sirianni, M.

    2005-10-01

    Since the last ISR 2003-02 on the use of Earth observations for a source of flat field illumination, several hundred more observations have been obtained with the full set of HRC standard filters and four narrow band WFC filters. While most of these observation show streaks or other nonuniform illumination, a significant subset are defect free and can be used to construct complete LP-flats. Many of the existing pipeline flats are confirmed to a precision of ~1%, which validates the stellar L-flat technique. Exceptions are the WFC, where a shutter light leak causes a systematic central contamination of a few percent and limits the verification accuracy to ~2%. Other exceptions are the four longest wavelength HRC filters, which show systematic differences with the pipeline flats. This discrepancy is apparently caused by stray light originating from the detector surface, where most of the longest wavelength photons are reflected and then scattered back from nearby focal plane structures. Because this complete set of HRC Earth flats is more appropriate than the pipeline flats for large diffuse objects such as the Moon, Jupiter, or the Orion Nebula, the set is now available on the STScI/ACS website. Earth flats also measure the small and intermediate scale P-flat structure. Due to slight deviations from OTA like illumination in the lab, the flat field corrections in the dust mote regions are 1-2% better with Earth flats. The trend found in ACS ISR 2005-09 for an increase toward the UV for more pixels with non-Poisson statistical distributions is confirmed for the F330W Earth flats, where up to 3% of the pixels are in error by >1%. Most of this newly discovered population of deviant pixels are dark with low responses; however, the effect of these erroneous P-flat values on stellar photometry is less than 0.1%.

  16. Earth meandering

    NASA Astrophysics Data System (ADS)

    Asadiyan, H.; Zamani, A.

    2009-04-01

    In this paper we try to put away current Global Tectonic Model to look the tectonic evolution of the earth from new point of view. Our new dynamic model is based on study of river meandering (RM) which infer new concept as Earth meandering(EM). In a universal gravitational field if we consider a clockwise spiral galaxy model rotate above Ninety East Ridge (geotectonic axis GA), this system with applying torsion field (likes geomagnetic field) in side direction from Rocky Mt. (west geotectonic pole WGP) to Tibetan plateau TP (east geotectonic pole EGP),it seems that pulled mass from WGP and pushed it in EGP due to it's rolling dynamics. According to this idea we see in topographic map that North America and Green land like a tongue pulled from Pacific mouth toward TP. Actually this system rolled or meander the earth over itself fractaly from small scale to big scale and what we see in the river meandering and Earth meandering are two faces of one coin. River transport water and sediments from high elevation to lower elevation and also in EM, mass transport from high altitude-Rocky Mt. to lower altitude Himalaya Mt. along 'S' shape geodetic line-optimum path which connect points from high altitude to lower altitude as kind of Euler Elastica(EE). These curves are responsible for mass spreading (source) and mass concentration (sink). In this regard, tiltness of earth spin axis plays an important role, 'S' are part of sigmoidal shape which formed due to intersection of Earth rolling with the Earth glob and actual feature of transform fault and river meandering. Longitudinal profile in mature rivers as a part of 'S' curve also is a kind of EE. 'S' which bound the whole earth is named S-1(S order 1) and cube corresponding to this which represent Earth fracturing in global scale named C-1(cube order 1 or side vergence cube SVC), C-1 is a biggest cycle of spiral polygon, so it is not completely closed and it has separation about diameter of C-7. Inside SVC we introduce cone

  17. Intra unit cell electronic structure of the d-symmetry form factor density wave in the underdoped cuprates - Part I

    NASA Astrophysics Data System (ADS)

    Fujita, Kazuhiro; Hamidian, Mohammad; Edkins, Stephen; Kim, Chung Koo; MacKenzie, Andy; Eisaki, Hiroshi; Uchida, Shin-Ichi; Lawler, Michael; Kim, Eun-Ah; Sachdev, Subir; Davis, J. C.

    2015-03-01

    A central issue of cuprate superconductivity research is to understand the nature of the unknown phase called the pseudogap and its relationship to the d-wave superconductivity. To approach this we use spectroscopic imaging STM to study the electronic structure of Bi2Sr2CaCu2O8+δ. Using our recently developed technique of sub-lattice phase-resolved electronic structure visualization within each CuO2 unit-cell, we discovered a d-symmetry form factor density wave within the cuprate pseudogap state. In this talk, part I, we demonstrate that d-symmetry is the predominant form factor in the density wave within pseudogap states and show how this situation evolves upon doping.

  18. Bulk Magnetic Order in a Two Dimensional Ni1+/Ni2+ (d9/d8) Nickelate, Isoelectronic with Superconducting Cuprates

    SciTech Connect

    Poltavets, V.; Lokshin, K; Nevidomskyy, A; Croft, M; Tyson, T; Hadermann, J; Van Tendeloo, G; Egami, T; Kotliar, G; et al.

    2010-01-01

    The Ni{sup 1+}/Ni{sup 2+} states of nickelates have the identical (3d{sup 9}/3d{sup 8}) electronic configuration as Cu{sup 2+}/Cu{sup 3+} in the high temperature superconducting cuprates, and are expected to show interesting properties. An intriguing question is whether mimicking the electronic and structural features of cuprates would also result in superconductivity in nickelates. Here we report experimental evidence for a bulklike magnetic transition in La{sub 4}Ni{sub 3}O{sub 8} at 105 K. Density functional theory calculations relate the transition to a spin density wave nesting instability of the Fermi surface.

  19. Spin-Fluctuation-Driven Nematic Charge-Density Wave in Cuprate Superconductors: Impact of Aslamazov-Larkin Vertex Corrections.

    PubMed

    Yamakawa, Youichi; Kontani, Hiroshi

    2015-06-26

    We present a microscopic derivation of the nematic charge-density wave (CDW) formation in cuprate superconductors based on the three-orbital d-p Hubbard model by introducing the vertex correction (VC) into the charge susceptibility. The CDW instability at q=(Δ(FS),0), (0,Δ(FS)) appears when the spin fluctuations are strong, due to the strong charge-spin interference represented by the VC. Here, Δ(FS) is the wave number between the neighboring hot spots. The obtained spin-fluctuation-driven CDW is expressed as the "intra-unit-cell orbital order" accompanied by the charge transfer between the neighboring atomic orbitals, which is actually observed by the scanning tunneling microscope measurements. We predict that the cuprate CDW and the nematic orbital order in Fe-based superconductors are closely related spin-fluctuation-driven phenomena. PMID:26197139

  20. Material and Doping Dependence of the Nodal and Anti-Nodal Dispersion Renormalizations in Single- and Multi-Layer Cuprates

    SciTech Connect

    Johnston, S.; Lee, W.S.; Nowadnick, E.A.; Moritz, B.; Shen, Z.-X.; Devereaux, T.P.; /Stanford U., Geballe Lab. /SLAC

    2010-02-15

    In this paper we present a review of bosonic renormalization effects on electronic carriers observed from angle-resolved photoemission spectra in the cuprates. Specifically, we discuss the viewpoint that these renormalizations represent coupling of the electrons to the lattice and review how materials dependence, such as the number of CuO{sub 2} layers, and doping dependence can be understood straightforwardly in terms of several aspects of electron-phonon coupling in layered correlated materials.

  1. Is the pseudogap in the high T{sub c} cuprates evidence for dynamic van Hove Jahn-Teller effects?

    SciTech Connect

    Markiewicz, R.S.

    1995-10-01

    Angle-resolved photoemission has demonstrated that in optimally doped YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO) and Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}, the van Hove singularity (vHs) is pinned close to the Fermi level. Such a pinning was predicted by the vHs scenario, due to strong electron-phonon coupling. This coupling arises for a novel Jahn-Teller (JT) effect, in which a structural distortion splits the degeneracy of the two vHs`s. In the lanthanum cuprates, there appears to be a sequence of dynamic JT phases, possibly terminating in a low-temperature static JT phase. The highest-temperature JT phase corresponds to the onset of octahedral tilts in the La cuprates (pyramidal tilts in YBCO), can can be identified with the experimentally observed pseudogap phase. Here the author summarizes recent experimental evidence for such a dynamic JT effect in the cuprates.

  2. Effective single-band models for the high-Tc cuprates. I. Coulomb interactions

    NASA Astrophysics Data System (ADS)

    Feiner, L. F.; Jefferson, J. H.; Raimondi, R.

    1996-04-01

    Starting with the three-band extended Hubbard model (or d-p model) widely used to represent the CuO2 planes in the high-Tc cuprates, we make a systematic reduction to an effective single-band model using a previously developed cell-perturbation method. The range of parameters for which this mapping is a good approximation is explored in the full Zaanen-Sawatzky-Allen diagram (copper Coulomb repulsion Ud versus charge-transfer energy ɛ), together with an investigation of the validity of a further mapping to an effective charge-spin (t-J-V) model. The variation of the effective single-band parameters with the parameters of the underlying multi-band model is investigated in detail, and the parameter regime where the model represents the high-Tc cuprates is examined for specific features that might distinguish it from the general case. In particular, we consider the effect of Coulomb repulsions on oxygen (Up) and between copper and oxygen (Vpd). We find that the reduction to an effective single-band model is generally valid for describing the low-energy physics, and that Vpd and Up (unless unrealistically large) actually slightly improve the convergence of the cell-perturbation method. Unlike in the usual single-band Hubbard model, the effective intercell hopping and Coulomb interactions are different for electrons and holes. We find that this asymmetry, which vanishes in the extreme Mott-Hubbard regime (Ud<<ɛ), is quite appreciable in the charge-transfer regime (Ud>~ɛ), particularly for the effective Coulomb interactions. We show that for doped holes (forming Zhang-Rice singlets) on neighboring cells the interaction induced by Vpd can even be attractive due to locally enhanced pd hybridization, while this cannot occur for electrons. The Coulomb interaction induced by Up is always repulsive; in addition Up gives rise to a ferromagnetic spin-spin interaction which opposes antiferromagnetic superexchange. We show that for hole-doped systems this leads to a subtle

  3. Comparative studies of the scanning tunneling spectra in cuprate and iron-arsenide superconductors

    NASA Astrophysics Data System (ADS)

    Yeh, N.-C.; Teague, M. L.; Beyer, A. D.; Shen, B.; Wen, H.-H.

    2012-12-01

    We report scanning tunneling spectroscopic studies of cuprate and iron-arsenic superconductors, including YBa2Cu3O7-δ (Y-123, Tc = 93 K), Sr0.9La0.1CuO2 (La-112, Tc = 43 K), and the “122” compounds Ba(Fe1-xCox)2As2 (Co-122 with x = 0.06, 0.08, 0.12 for Tc = 14, 24, 20 K). In zero field (H = 0), spatially homogeneous coherence peaks at energies ω = ± ΔSC flanked by spectral “shoulders” at ±Δeff are found in hole-type Y-123. In contrast, only a pair of spatially homogeneous peaks is seen in electron-type La-112 at ± Δeff. For H > 0, pseudogap (ΔPG) features are revealed inside the vortices, with ΔPG = [(Δeff)2-(ΔSC)2]1/2 > ΔSC in Y-123 and ΔPG < ΔSC in La-112, suggesting that the physical origin of ΔPG is a competing order coexisting with superconductivity. Additionally, Fourier transformation (FT) of the Y-123 spectra exhibits two types of spectral peaks, one type is associated with ω-dependent quasiparticle interference (QPI) wave-vectors and the other consists of ω-independent wave-vectors due to competing orders and (π,π) magnetic resonances. For the multi-band Co-122 compounds, two-gap superconductivity is found for all doping levels. Magnetic resonant modes that follow the temperature dependence of the superconducting gaps are also identified. These findings, together with the ω- and x-dependent QPI spectra, are consistent with a sign-changing s-wave pairing symmetry in the Co-122 iron arsenides. Our comparative studies suggest that the commonalities among the cuprate and the ferrous superconductors include the proximity to competing orders, antiferromagnetic (AFM) spin fluctuations and magnetic resonances in the superconducting (SC) state, and the unconventional pairing symmetries with sign-changing order parameters on different parts of the Fermi surface.

  4. NMR Studies of the original magnetic properties of the cuprates: influence of impurities and defects.

    NASA Astrophysics Data System (ADS)

    Alloul, Henri

    1998-03-01

    The cuprates display original magnetic properties, both in their insulating and metallic phases. In underdoped metallic systems, a pseudo gap in the density of magnetic q=3D0 excitations is observed from local susceptibility measurements, as well as from specific heat and transport properties. A pseudo spin-gap in the AF excitations at the AF wave vector is detected both by NMR and inelastic neutron scattering. From the NMR measurements it can be concluded that these magnetic anomalies are quite similar in single layer(J. Bobroff, H.. Alloul, P. Mendels, V. Viallet, J. F. Marucco and D. Colson, Phys. Rev. Letters 78, 3757 (1997).), bilayer and trilayer underdoped cuprates. The modifications of magnetic properties induced by substitutions or defects in the planes, which do not modify appreciably the charge transfer have been studied. The spatial dependence of the spin susceptibility \\chi ' (r) of the pure material can be directly probed through the study of the modifications of the NMR spectra of various nuclei (^89Y, ^17O, ^63Cu) induced by such localised magnetic impurities. Large qualitative differences between the underdoped and slightly overdoped YBCO are evidenced from ^17O NMR line broadening in Ni substituted YBCO. This allows us to propose a quite powerful method for studying the q and T dependence of the static magnetic susceptibility (J. Bobroff et al, Phys. Rev. Letters 78, 3757 (1997).). The impurity magnetic state also directly reflects the occurence of electronic correlations in the metallic state. The case of Zn will be examined in some detail. ^89Y NMR has revealed that the substitution of this 3d^10 non magnetic atom on a Cu site induces a Curie like contribution to the local susceptibility on the near neighbour coppers ( A. V. Mahajan, H. Alloul, G. Collin and J. F. Marucco, Physical Review Letters 72, 3100 (1994).). The effective induced moment decreases with hole doping and becomes rather weak, but is still present for optimal doping

  5. Co-existence of spin fluctuation and superconductivity in electron doped cuprate Pr1-xLaCexCuO4

    NASA Astrophysics Data System (ADS)

    Song, Dongjoon; Park, S. R.; Kim, Chul; Choi, S. K.; Jung, W. S.; Koh, Y. Y.; Kim, Y. K.; Eisaki, H.; Yoshida, Y.; Kim, C.

    2012-02-01

    Even though spin fluctuation has been proposed to be as the pairing glue in the cuprate high temperature superconductivity, there is lack of a clear evidence for its coupling to electron. One of the reasons is that, for hole doped cuprates, both anti-ferromagnetism (AFM) and recently proposed charge ordering effects due to Fermi surface nesting occur in the same region of the momentum space (anti-nodal region). On the other hand, electron doped cuprates are known to have the pseudo gap effect at hot spots from AFM band renormalization. This fact makes it advantageous to investigate electron doped cuprates for the spin fluctuation issue. We performed ARPES studies on superconducting electron doped cuprates PLCCO (x=0.1, 0.15, 0.18) to investigate the relation between the spin fluctuation and superconductivity. We observe pseudo gap for all the dopings, which indicates that the short range AFM ordering survives far away from the AFM phase boundary. This coincidence of the short range AFM and superconductivity even in the over doped state may support the spin fluctuation scenarios at least in the electron doped side.

  6. Stimulated emission of Cooper pairs in a high-temperature cuprate superconductor

    PubMed Central

    Zhang, Wentao; Miller, Tristan; Smallwood, Christopher L.; Yoshida, Yoshiyuki; Eisaki, Hiroshi; Kaindl, R. A.; Lee, Dung-Hai; Lanzara, Alessandra

    2016-01-01

    The concept of stimulated emission of bosons has played an important role in modern science and technology, and constitutes the working principle for lasers. In a stimulated emission process, an incoming photon enhances the probability that an excited atomic state will transition to a lower energy state and generate a second photon of the same energy. It is expected, but not experimentally shown, that stimulated emission contributes significantly to the zero resistance current in a superconductor by enhancing the probability that scattered Cooper pairs will return to the macroscopically occupied condensate instead of entering any other state. Here, we use time- and angle-resolved photoemission spectroscopy to study the initial rise of the non-equilibrium quasiparticle population in a Bi2Sr2CaCu2O8+δ cuprate superconductor induced by an ultrashort laser pulse. Our finding reveals significantly slower buildup of quasiparticles in the superconducting state than in the normal state. The slower buildup only occurs when the pump pulse is too weak to deplete the superconducting condensate, and for cuts inside the Fermi arc region. We propose this is a manifestation of stimulated recombination of broken Cooper pairs, and signals an important momentum space dichotomy in the formation of Cooper pairs inside and outside the Fermi arc region. PMID:27364682

  7. Long-range charge-density-wave proximity effect at cuprate/manganate interfaces.

    PubMed

    Frano, A; Blanco-Canosa, S; Schierle, E; Lu, Y; Wu, M; Bluschke, M; Minola, M; Christiani, G; Habermeier, H U; Logvenov, G; Wang, Y; van Aken, P A; Benckiser, E; Weschke, E; Le Tacon, M; Keimer, B

    2016-08-01

    The interplay between charge density waves (CDWs) and high-temperature superconductivity is currently under intense investigation. Experimental research on this issue is difficult because CDW formation in bulk copper oxides is strongly influenced by random disorder, and a long-range-ordered CDW state in high magnetic fields is difficult to access with spectroscopic and diffraction probes. Here we use resonant X-ray scattering in zero magnetic field to show that interfaces with the metallic ferromagnet La2/3Ca1/3MnO3 greatly enhance CDW formation in the optimally doped high-temperature superconductor YBa2Cu3O6+δ (δ ∼ 1), and that this effect persists over several tens of nanometres. The wavevector of the incommensurate CDW serves as an internal calibration standard of the charge carrier concentration, which allows us to rule out any significant influence of oxygen non-stoichiometry, and to attribute the observed phenomenon to a genuine electronic proximity effect. Long-range proximity effects induced by heterointerfaces thus offer a powerful method to stabilize the charge-density-wave state in the cuprates and, more generally, to manipulate the interplay between different collective phenomena in metal oxides. PMID:27322824

  8. Ground state of underdoped cuprates in vicinity of superconductor-to-insulator transition

    DOE PAGESBeta

    Wu, Jie; Bollinger, Anthony T.; Sun, Yujie; Božović, Ivan

    2016-08-15

    When an insulating underdoped cuprate is doped beyond a critical concentration (xc), high-temperature superconductivity emerges. We have synthesized a series of La2–xSrxCuO4 (LSCO) samples using the combinatorial spread technique that allows us to traverse the superconductor-to-insulator transition (SIT) in extremely fine doping steps, Δx≈0.00008. We have measured the Hall resistivity (ρH) as a function of temperature down to 300 mK in magnetic fields up to 9 T. At very low temperatures, ρH shows an erratic behavior, jumps and fluctuations exceeding 100%, hysteresis, and memory effects, indicating that the insulating ground state is a charge-cluster glass (CCG). Furthermore, based on themore » phase diagram depicted in our experiment, we propose a unified picture to account for the anomalous electric transport in the vicinity of the SIT, suggesting that the CCG is in fact a disordered and glassy version of the charge density wave.« less

  9. Stimulated emission of Cooper pairs in a high-temperature cuprate superconductor.

    PubMed

    Zhang, Wentao; Miller, Tristan; Smallwood, Christopher L; Yoshida, Yoshiyuki; Eisaki, Hiroshi; Kaindl, R A; Lee, Dung-Hai; Lanzara, Alessandra

    2016-01-01

    The concept of stimulated emission of bosons has played an important role in modern science and technology, and constitutes the working principle for lasers. In a stimulated emission process, an incoming photon enhances the probability that an excited atomic state will transition to a lower energy state and generate a second photon of the same energy. It is expected, but not experimentally shown, that stimulated emission contributes significantly to the zero resistance current in a superconductor by enhancing the probability that scattered Cooper pairs will return to the macroscopically occupied condensate instead of entering any other state. Here, we use time- and angle-resolved photoemission spectroscopy to study the initial rise of the non-equilibrium quasiparticle population in a Bi2Sr2CaCu2O8+δ cuprate superconductor induced by an ultrashort laser pulse. Our finding reveals significantly slower buildup of quasiparticles in the superconducting state than in the normal state. The slower buildup only occurs when the pump pulse is too weak to deplete the superconducting condensate, and for cuts inside the Fermi arc region. We propose this is a manifestation of stimulated recombination of broken Cooper pairs, and signals an important momentum space dichotomy in the formation of Cooper pairs inside and outside the Fermi arc region. PMID:27364682

  10. Material-parameter Dependence of Superconductivity in High-temperature Cuprates

    NASA Astrophysics Data System (ADS)

    Yanagisawa, Takashi; Miyazaki, Mitake; Yamaji, Kunihiko

    We show that there is an interesting correlation between material parameters and critical temperature Tc in cuprate high temperature superconductors. Our analysis is based on the d-p model, that is, the three-band Hubbard model including d and p orbitals explicitly. This model contains many parameters; the transfer integrals tdp and tpp, the energy levels ɛp and ɛd, and the Coulomb interaction parameters Ud and Up. Our main results are the following: (a) Tc increases as ɛp-ɛd is increased for Up = 0, (2) Tc is lowered with increase of Up when ɛp-ɛd > 0, (3) Tc is increased with increase of Up when ɛp-ɛd < 0, (4) Tc has a minimum at near ɛp-ɛd = 0 as a function of ɛp-ɛd when Ud and Up are comparable, (5) Ud induces dx2-y2 pairing while Up induces dxy pairing, (6) Tc has a peak as a function of tpp. The results imply that Tc will increase if we can suppress Up. The role of Up is consistent with the experimental tendency that Tc increases as the relative ratio of the hole density at oxygen site to that at copper site is increased, which means that when Up increases, the number of p holes is decreased and Tc is also decreased.

  11. Two regimes in conductivity and the Hall coefficient of underdoped cuprates in strong magnetic fields.

    PubMed

    Gor'kov, L P; Teitel'baum, G B

    2014-01-29

    We address recent experiments shedding light on the energy spectrum of under and optimally doped cuprates at temperatures above the superconducting transition. Angle resolved photoemission reveals coherent excitation only near nodal points on parts of the 'bare' Fermi surface known as the Fermi arcs. The question debated in the literature is whether the small normal pocket, seen via quantum oscillations, exists at higher temperatures or forms below a charge order transition in strong magnetic fields. Assuming the former case as a possibility, expressions are derived for the resistivity and the Hall coefficient (in weak and strong magnetic fields) with both types of carriers participating in the transport. There are two regimes. At higher temperatures (at a fixed field) electrons are dragged by the Fermi arcs' holes. The pocket being small, its contribution to conductivity and the Hall coefficient is negligible. At lower temperatures electrons decouple from holes behaving as a Fermi gas in the magnetic field. As the mobility of holes on the arcs decreases in strong fields with a decrease of temperature, below a crossover point the pocket electrons prevail, changing the sign of the Hall coefficient in the low temperature limit. Such behavior finds its confirmation in recent high-field experiments. PMID:24389670

  12. 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.

  13. Gutzwiller charge phase diagram of cuprates, including electron–phonon coupling effects

    DOE PAGESBeta

    Markiewicz, R. S.; Seibold, G.; Lorenzana, J.; Bansil, A.

    2015-02-01

    Besides significant electronic correlations, high-temperature superconductors also show a strong coupling of electrons to a number of lattice modes. Combined with the experimental detection of electronic inhomogeneities and ordering phenomena in many high-Tc compounds, these features raise the question as to what extent phonons are involved in the associated instabilities. Here we address this problem based on the Hubbard model including a coupling to phonons in order to capture several salient features of the phase diagram of hole-doped cuprates. Charge degrees of freedom, which are suppressed by the large Hubbard U near half-filling, are found to become active at amore » fairly low doping level. We find that possible charge order is mainly driven by Fermi surface nesting, with competition between a near-(π, π) order at low doping and antinodal nesting at higher doping, very similar to the momentum structure of magnetic fluctuations. The resulting nesting vectors are generally consistent with photoemission and tunneling observations, evidence for charge density wave order in YBa₂Cu₃O7-δ including Kohn anomalies, and suggestions of competition between one- and two-q-vector nesting.« less

  14. Gutzwiller charge phase diagram of cuprates, including electron–phonon coupling effects

    SciTech Connect

    Markiewicz, R. S.; Seibold, G.; Lorenzana, J.; Bansil, A.

    2015-02-01

    Besides significant electronic correlations, high-temperature superconductors also show a strong coupling of electrons to a number of lattice modes. Combined with the experimental detection of electronic inhomogeneities and ordering phenomena in many high-Tc compounds, these features raise the question as to what extent phonons are involved in the associated instabilities. Here we address this problem based on the Hubbard model including a coupling to phonons in order to capture several salient features of the phase diagram of hole-doped cuprates. Charge degrees of freedom, which are suppressed by the large Hubbard U near half-filling, are found to become active at a fairly low doping level. We find that possible charge order is mainly driven by Fermi surface nesting, with competition between a near-(π, π) order at low doping and antinodal nesting at higher doping, very similar to the momentum structure of magnetic fluctuations. The resulting nesting vectors are generally consistent with photoemission and tunneling observations, evidence for charge density wave order in YBa₂Cu₃O7-δ including Kohn anomalies, and suggestions of competition between one- and two-q-vector nesting.

  15. Stimulated emission of Cooper pairs in a high-temperature cuprate superconductor

    NASA Astrophysics Data System (ADS)

    Zhang, Wentao; Miller, Tristan; Smallwood, Christopher L.; Yoshida, Yoshiyuki; Eisaki, Hiroshi; Kaindl, R. A.; Lee, Dung-Hai; Lanzara, Alessandra

    2016-07-01

    The concept of stimulated emission of bosons has played an important role in modern science and technology, and constitutes the working principle for lasers. In a stimulated emission process, an incoming photon enhances the probability that an excited atomic state will transition to a lower energy state and generate a second photon of the same energy. It is expected, but not experimentally shown, that stimulated emission contributes significantly to the zero resistance current in a superconductor by enhancing the probability that scattered Cooper pairs will return to the macroscopically occupied condensate instead of entering any other state. Here, we use time- and angle-resolved photoemission spectroscopy to study the initial rise of the non-equilibrium quasiparticle population in a Bi2Sr2CaCu2O8+δ cuprate superconductor induced by an ultrashort laser pulse. Our finding reveals significantly slower buildup of quasiparticles in the superconducting state than in the normal state. The slower buildup only occurs when the pump pulse is too weak to deplete the superconducting condensate, and for cuts inside the Fermi arc region. We propose this is a manifestation of stimulated recombination of broken Cooper pairs, and signals an important momentum space dichotomy in the formation of Cooper pairs inside and outside the Fermi arc region.

  16. Resonant Two-Magnon Raman Scattering in Cuprate Antiferromagnetic Insulators and Superconductors.

    NASA Astrophysics Data System (ADS)

    Blumberg, G.; Abbamonte, P.; Klein, M. V.

    1996-03-01

    We present results of low-temperature two-magnon resonance Raman excitation profile measurements for single layer Sr_2CuO_2Cl2 and bilayer YBa_2Cu_3O6 + δ antiferromagnets over the excitation region from 1.65 to 3.05 eV. These data reveal composite structure of the B_1g two-magnon line shape peaked at ~ 2.7J and ~ 4J and strong nonmonotonic dependence of the scattering intensity on excitation energy. Resonant magnetic scattering contributes also to A_1g and B_2g channels. We analyze these data using the triple resonance theory of Chubukov and Frenkel(A. Chubukov and D. Frenkel, Phys. Rev. Lett.74), 3057 (1995). and deduce information about magnetic interaction (J and J_⊥) and band parameters (NN hopping t and charge transfer gap 2Δ) in these antiferromagnets.(G. Blumberg et. al.), Preprint cond-mat/9511080. The ~ 3J spin superexchange excitation persists upon hole doping and is present in superconductors, proving the universality of the short wavelength magnetic excitations in the cuprate superconducting metals and the parent antiferromagnetic insulators.(G. Blumberg et. al.), Phys. Rev. B 49, 13 295 (1994).

  17. HTSC cuprate films doped with nanoparticles and their electrodynamics, determined by Abrikosov vortices

    NASA Astrophysics Data System (ADS)

    Flis, V. S.; Kalenyuk, A. A.; Kasatkin, A. L.; Moskalyuk, V. O.; Rebikov, A. I.; Svechnikov, V. L.; Tret'yachenko, K. G.; Pan, V. M.

    2010-01-01

    This paper presents the results of a comprehensive study of the relationship of the structural and electrodynamic characteristics of quasi-single-crystal films of the HTSC cuprate YBa2Cu3O7-δ (YBCO) with various concentrations (several mass percent) of nanosize inclusions of the perovskitelike phase of BaZrO3 (BZO). High-resolution electron microscopy is used to investigate the nanostructure of the fabricated films and to determine the main types of defects that cause strong pinning of Abrikosov vortices and, accordingly, large critical current densities. The results of theoretically modelling the genesis of the defect nanostructure that appears in such films and its influence on the critical current are presented. The magnetic and transport properties of HTSC films made from YBCO(BZO) have been experimentally studied. The temperature, magnetic-field, and magnetic-orientation dependences of the critical current density of the test films are found. The results of an experimental investigation of the high-frequency properties of YBZO(BZO) films—the surface microwave impedance of the films in the linear and nonlinear regimes—are also given. The experimental results are discussed, and the influence of the nanostructure of the impurity phase on the electrodynamic characteristics of the HTSC films is analyzed.

  18. The rate of quasiparticle recombination probes the onset of coherence in cuprate superconductors

    DOE PAGESBeta

    Hinton, J. P.; Thewalt, E.; Alpichshev, Z.; Mahmood, F.; Koralek, J. D.; Chan, M. K.; Veit, M. J.; Dorow, C. J.; Barisic, N.; Kemper, A. F.; et al

    2016-04-13

    In the underdoped copper-oxides, high-temperature superconductivity condenses from a nonconventional metallic ”pseudogap” phase that exhibits a variety of non-Fermi liquid properties. Recently, it has become clear that a charge density wave (CDW) phase exists within the pseudogap regime. This CDW coexists and competes with superconductivity (SC) below the transition temperature Tc, suggesting that these two orders are intimately related. Here we show that the condensation of the superfluid from this unconventional precursor is reflected in deviations from the predictions of BSC theory regarding the recombination rate of quasiparticles. We report a detailed investigation of the quasiparticle (QP) recombination lifetime, τqp,more » as a function of temperature and magnetic field in underdoped HgBa2CuO4+δ (Hg-1201) and YBa2Cu3O6+x (YBCO) single crystals by ultrafast time-resolved reflectivity. We find that τqp(T) exhibits a local maximum in a small temperature window near Tc that is prominent in underdoped samples with coexisting charge order and vanishes with application of a small magnetic field. We explain this unusual, non-BCS behavior by positing that Tc marks a transition from phase-fluctuating SC/CDW composite order above to a SC/CDW condensate below. Lastly, our results suggest that the superfluid in underdoped cuprates is a condensate of coherently-mixed particle-particle and particle-hole pairs.« less

  19. Random Walks in Anderson's Garden: A Journey from Cuprates to Cooper Pair Insulators and Beyond

    NASA Astrophysics Data System (ADS)

    Baskaran, G.

    Anderson's Garden is a drawing presented to Philip W. Anderson on the eve of his 60th birthday celebration, in 1983, by a colleague (author unknown). This cartoon (Fig. 1) succinctly depicts some of Anderson's pre-1983 works. As an avid reader of Anderson's papers, a random walk in Anderson's garden had become a part of my routine since graduate school days. This was of immense help and prepared me for a wonderful collaboration with Anderson on the theory of high-Tc cuprates and quantum spin liquids at Princeton. Here I narrate this story, ending with a brief summary of my ongoing theoretical efforts to extend Anderson's RVB theory for superconductivity to encompass the recently observed high-temperature (Tc ~ 203K) superconductivity in solid H2S at pressure ~200GPa. In H2S molecule, four valence electrons form two saturated covalent bonds, H-S-H. These bond singlets are confined Cooper pairs close to chemical potential. Solid H2S is a Cooper pair insulator. Pressure changes the structure and not the number of valence electrons. Bond singlet pairing tendency continues and new S-S and H-H bonds are formed. S-S bonds are mostly saturated. However, hydrogen sublattice has unsaturated H-H bonds. It prepares ground for a RVB superconducting state.

  20. Quantum oscillations and nodal pockets from Fermi surface reconstruction in the underdoped cuprates

    NASA Astrophysics Data System (ADS)

    Harrison, Neil

    2012-02-01

    Fermiology in the underdoped high Tc cuprates presents us with unique challenges, requiring experimentalists to look deeper into the data than is normally required for clues. Recent measurements of an oscillatory chemical potential affecting the oscillations at high magnetic fields provide a strong indication of a single type of carrier pocket. When considered in conjunction with photoemission and specific heat measurements, a Fermi surface comprised almost entirely of nodal pockets is suggested. The mystery of the Fermi surface is deepened, however, by a near doping-independent Fermi surface cross-sectional area and negative Hall and Seebeck coefficients. We explore ways in which these findings can be reconciled, taking an important hint from the diverging effective mass yielded by quantum oscillations at low dopings. The author wishes to thank Suchitra Sebastian, Moaz Atarawneh, Doug Bonn, Walter Hardy, Ruixing Liang, Charles Mielke and Gilbert Lonzarich who have contributed to this work. The work is supported by the NSF through the NHMFL and by the DOE project ``Science at 100 tesla.''

  1. Origin and consequences of the disorder-induced inhomogeneities in cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Chakraborty, Debmalya; Sensarma, Rajdeep; Ghosal, Amit

    The effect of potential impurities on cuprate superconductors are investigated within a formalism suitable for addressing the complex interplay of the bare repulsive electronic correlations and disorder, both being strong. We show that the mechanism governing the demise of superconductivity is rather subtle and differs from the conventional weak-coupling descriptions. While the superconductivity remains surprisingly robust for up to moderate disorder, it crashes down sharply at stronger disorders. The initial robustness is attributed to the strong repulsive correlations that smear out charge inhomogeneities by reorganizing the hopping on the bonds prohibiting formation of superconducting ``islands''. However, with increasing strength of disorder, the potential difference across some bonds reach the scale of the bandwidth and the overall energy of the system is reduced by prohibiting hopping on such links. Integrating this concept within our formalism, we show that the correlations fail to homogenize the system across these ``cut-bonds''. This produces Mott-insulating, Anderson-insulating, as well as locally superconducting regions interspersed among each other at strong disorder, eventually destroying the global superconductivity.

  2. The rate of quasiparticle recombination probes the onset of coherence in cuprate superconductors

    PubMed Central

    Hinton, J. P.; Thewalt, E.; Alpichshev, Z.; Mahmood, F.; Koralek, J. D.; Chan, M. K.; Veit, M. J.; Dorow, C. J.; Barišić, N.; Kemper, A. F.; Bonn, D. A.; Hardy, W. N.; Liang, Ruixing; Gedik, N.; Greven, M.; Lanzara, A.; Orenstein, J.

    2016-01-01

    In the underdoped copper-oxides, high-temperature superconductivity condenses from a nonconventional metallic ”pseudogap” phase that exhibits a variety of non-Fermi liquid properties. Recently, it has become clear that a charge density wave (CDW) phase exists within the pseudogap regime. This CDW coexists and competes with superconductivity (SC) below the transition temperature Tc, suggesting that these two orders are intimately related. Here we show that the condensation of the superfluid from this unconventional precursor is reflected in deviations from the predictions of BSC theory regarding the recombination rate of quasiparticles. We report a detailed investigation of the quasiparticle (QP) recombination lifetime, τqp, as a function of temperature and magnetic field in underdoped HgBa2CuO4+δ (Hg-1201) and YBa2Cu3O6+x (YBCO) single crystals by ultrafast time-resolved reflectivity. We find that τqp(T ) exhibits a local maximum in a small temperature window near Tc that is prominent in underdoped samples with coexisting charge order and vanishes with application of a small magnetic field. We explain this unusual, non-BCS behavior by positing that Tc marks a transition from phase-fluctuating SC/CDW composite order above to a SC/CDW condensate below. Our results suggest that the superfluid in underdoped cuprates is a condensate of coherently-mixed particle-particle and particle-hole pairs. PMID:27071712

  3. Interplay between pair density waves and random field disorders in the pseudogap regime of cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Chan, Cheung

    2016-05-01

    To capture various experimental results in the pseudogap regime of the underdoped cuprate superconductors for temperature T

  4. The rate of quasiparticle recombination probes the onset of coherence in cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Hinton, J. P.; Thewalt, E.; Alpichshev, Z.; Mahmood, F.; Koralek, J. D.; Chan, M. K.; Veit, M. J.; Dorow, C. J.; Barišić, N.; Kemper, A. F.; Bonn, D. A.; Hardy, W. N.; Liang, Ruixing; Gedik, N.; Greven, M.; Lanzara, A.; Orenstein, J.

    2016-04-01

    In the underdoped copper-oxides, high-temperature superconductivity condenses from a nonconventional metallic ”pseudogap” phase that exhibits a variety of non-Fermi liquid properties. Recently, it has become clear that a charge density wave (CDW) phase exists within the pseudogap regime. This CDW coexists and competes with superconductivity (SC) below the transition temperature Tc, suggesting that these two orders are intimately related. Here we show that the condensation of the superfluid from this unconventional precursor is reflected in deviations from the predictions of BSC theory regarding the recombination rate of quasiparticles. We report a detailed investigation of the quasiparticle (QP) recombination lifetime, τqp, as a function of temperature and magnetic field in underdoped HgBa2CuO4+δ (Hg-1201) and YBa2Cu3O6+x (YBCO) single crystals by ultrafast time-resolved reflectivity. We find that τqp(T ) exhibits a local maximum in a small temperature window near Tc that is prominent in underdoped samples with coexisting charge order and vanishes with application of a small magnetic field. We explain this unusual, non-BCS behavior by positing that Tc marks a transition from phase-fluctuating SC/CDW composite order above to a SC/CDW condensate below. Our results suggest that the superfluid in underdoped cuprates is a condensate of coherently-mixed particle-particle and particle-hole pairs.

  5. Long-range charge-density-wave proximity effect at cuprate/manganate interfaces

    NASA Astrophysics Data System (ADS)

    Frano, A.; Blanco-Canosa, S.; Schierle, E.; Lu, Y.; Wu, M.; Bluschke, M.; Minola, M.; Christiani, G.; Habermeier, H. U.; Logvenov, G.; Wang, Y.; van Aken, P. A.; Benckiser, E.; Weschke, E.; Le Tacon, M.; Keimer, B.

    2016-08-01

    The interplay between charge density waves (CDWs) and high-temperature superconductivity is currently under intense investigation. Experimental research on this issue is difficult because CDW formation in bulk copper oxides is strongly influenced by random disorder, and a long-range-ordered CDW state in high magnetic fields is difficult to access with spectroscopic and diffraction probes. Here we use resonant X-ray scattering in zero magnetic field to show that interfaces with the metallic ferromagnet La2/3Ca1/3MnO3 greatly enhance CDW formation in the optimally doped high-temperature superconductor YBa2Cu3O6+δ (δ ~ 1), and that this effect persists over several tens of nanometres. The wavevector of the incommensurate CDW serves as an internal calibration standard of the charge carrier concentration, which allows us to rule out any significant influence of oxygen non-stoichiometry, and to attribute the observed phenomenon to a genuine electronic proximity effect. Long-range proximity effects induced by heterointerfaces thus offer a powerful method to stabilize the charge-density-wave state in the cuprates and, more generally, to manipulate the interplay between different collective phenomena in metal oxides.

  6. High On/Off Ratio Memristive Switching of Manganite/Cuprate Bilayer by Interfacial Magnetoelectricity

    DOE PAGESBeta

    Shen, Xiao; Pennycook, Timothy J.; Hernandez-Martin, David; Pérez, Ana; Puzyrev, Yevgeniy S.; Liu, Yaohua; te Velthuis, Suzanne G. E.; Freeland, John W.; Shafer, Padraic; Zhu, Chenhui; et al

    2016-05-27

    Memristive switching serves as the basis for a new generation of electronic devices. Conventional memristors are two-terminal devices in which the current is turned on and off by redistributing point defects, e.g., vacancies. Memristors based on alternative mechanisms have been explored, but achieving both high on/off ratio and low switching energy, as needed in applications, remains a challenge. This paper reports memristive switching in La0.7Ca0.3MnO3/PrBa2Cu3O7 bilayers with an on/off ratio greater than 103 and results of density functional theory calculations in terms of which it is concluded that the phenomenon is likely the result of a new type of interfacialmore » magnetoelectricity. More specifically, this study shows that an external electric field induces subtle displacements of the interfacial Mn ions, which switches on/off an interfacial magnetic “dead layer”, resulting in memristive behavior for spin-polarized electron transport across the bilayer. The interfacial nature of the switching entails low energy cost, about of a tenth of atto Joule for writing/erasing a “bit”. To conclude, the results indicate new opportunities for manganite/cuprate systems and other transition metal oxide junctions in memristive applications.« less

  7. Signatures of strong correlation effects in resonant inelastic x-ray scattering studies on cuprates

    NASA Astrophysics Data System (ADS)

    Li, Wan-Ju; Lin, Cheng-Ju; Lee, Ting-Kuo

    2016-08-01

    Recently, spin excitations in doped cuprates have been measured using resonant inelastic x-ray scattering. The paramagnon dispersions show the large hardening effect in the electron-doped systems and seemingly doping independence in the hole-doped systems, with the energy scales comparable to that of the antiferromagnetic (AFM) magnons. This anomalous hardening effect and the lack of softening were partially explained by using the strong-coupling t -J model but with a three-site term [Nat. Commun. 5, 3314 (2014), 10.1038/ncomms4314], although the hardening effect is already present even without the latter. By considering the t -t'-t''-J model and using the slave-boson mean-field theory, we obtain, via the spin-spin susceptibility, the spin excitations in qualitative agreement with the experiments. The doping-dependent bandwidth due to the strong correlation physics is the origin of the hardening effect. We also show that dispersions in the AFM regime, different from those in the paramagnetic (PM) regime, hardly vary with dopant density. These excitations are mainly collective in nature instead of particle-hole-like. We further discuss the interplay and different contributions of these two kinds of excitations in the PM phase and show that the dominance of the collective excitation increases with decreasing dopant concentrations.

  8. Overview of recent magnetic studies of high T c cuprate parent compounds and related materials

    NASA Astrophysics Data System (ADS)

    Johnston, D. C.; Ami, T.; Borsa, F.; Canfield, P. C.; Carretta, P.; Cho, B. K.; Cho, J. H.; Chou, F. C.; Corti, M.; Crawford, M. K.; Dervenagas, P.; Erwin, R. W.; Fernandez-Baca, J. A.; Goldman, A. I.; Gooding, R. J.; Huang, Q.; Hundley, M. F.; Harlow, R. L.; Harmon, B. N.; Lascialfari, A.; Miller, L. L.; Ostenson, J. E.; Salem, N. M.; Stassis, C.; Sternlieb, B.; Suh, B. J.; Torgeson, D. R.; Vaknin, D.; Vos, K. J. E.; Wang, X.-L.; Wang, Z. R.; Xu, M.; Zarestky, J.

    Recent studies of the magnetic properties of several high superconducting transition temperature (T c ) cuprate parent compounds and related materials will be reviewed. The observations of a Heisenberg to XY-like crossover upon cooling below ˜ 300 K towards the Néel temperature T N =257 K and a subsequent magnetic field-induced XY-like to Ising-like crossover near T N in single crystals of the K2NiF4-type spin 1/2 model compound Sr2CuO2Cl2 will be described. The spin 1/2 linear chain compound Sr2CuO3, the parent of the Sr2CuO3+δ oxygen-doped superconductors, is found to exhibit classic Bonner-Fisher magnetic behavior, with a large antiferromagnetic Cu-Cu superexchange coupling constant. Studies of the evolution of La2-x SrxCuO4 with Sr doping in the insulating regime (x<0.05) will be summarized, which indicate that the doped holes reside in walls separating undoped domains. We have found that BaCuO2.1, a copper-oxygen cluster compound, exhibits ferromagnetic rather than antiferromagnetic Cu-Cu superexchange interactions. Finally, a summary of the magnetic properties of single crystals of the recently discovered RNi2B2C layered structure superconductors will be given.

  9. Stabilization of high Tc phase in bismuth cuprate superconductor by lead doping

    NASA Technical Reports Server (NTRS)

    Gupta, Ram. P.; Pachauri, J. P.; Khokle, W. S.; Nagpal, K. C.; Date, S. K.

    1991-01-01

    It has been widely ascertained that doping of lead in Bi-Sr-Ca-Cu-O systems promotes the growth of high T sub c (110 K) phase, improves critical current density, and lowers processing temperature. A systematic study was undertaken to determine optimum lead content and processing conditions to achieve these properties. A large number of samples with cationic compositions of Bi(2-x)Pb(x)Sr2Ca2Cu3 (x = 0.2 to 2.0) were prepared by conventional solid state reaction technique. Samples of all compositions were annealed together at a temperature and characterized through resistance temperature (R-T) measurements and x ray diffraction to determine the zero resistance temperature, T sub c(0) and to identify presence of phases, respectively. The annealing temperature was varied between 790 and 880 C to optimize processing parameters. Results are given. In brief, an optimum process is reported along with composition of leaded bismuth cuprate superconductor which yields nearly a high T sub c single phase with highly stable superconducting properties.

  10. Stabilization of high T(sub c) phase in bismuth cuprate superconductor by lead doping

    NASA Technical Reports Server (NTRS)

    Gupta, Ram. P.; Pachauri, J. P.; Khokle, W. S.; Nagpal, K. C.; Date, S. K.

    1990-01-01

    It has widely been ascertained that doping of lead in Bi:Sr:Ca:Cu:O systems promotes the growth of high T(sub c) (110 K) phase, improves critical current density, and lowers processing temperature. A systematic investigation is undertaken to determine optimum lead content and processing conditions to achieve these. A large number of samples with cationic compositions of Bi(2-x)Pb(x)Sr2Ca2Cu3 (x = 0.2 to 2.0) were prepared by conventional solid state reaction technique. Samples of all compositions were annealed together at a temperature and characterized through resistance-temperature (R-T) measurements and x ray diffraction (XRD) to determine the zero resistance temperature, T(sub c)(0) and to identify presence of phases, respectively. The annealing temperature was varied between 790 C to optimize processing parameters. Results are given. In brief, an optimum process is reported along with composition of leaded bismuth cuprate superconductor which yields nearly a high T(sub c) single phase with highly stable superconducting properties.

  11. d-Density Wave Scenario Description of the New Hidden Charge Order in Cuprates

    NASA Astrophysics Data System (ADS)

    Makhfudz, Imam

    2016-06-01

    In this paper, we show that the theory of high Tc superconductivity based on a microscopic model with d-density wave (DDW) scenario in the pseudogap phase is able to reproduce some of the most important features of the recent experimentally discovered hidden charge order in several families of Cuprates. In particular, by computing and comparing energies of charge orders of different modulation directions derived from a full microscopic theory with d-density wave scenario, the axial charge order ϕX(Y) with wavevector {Q} = (Q0,0)((0,Q0)) is shown to be unambiguously energetically more favorable over the diagonal charge order ϕX±Y with wavevector {Q} = (Q0, ± Q0) at least in commensurate limit, to be expected also to hold even to more general incommensurate case, in agreement with experiment. The two types of axial charge order ϕX and ϕY are degenerate by symmetry. We find that within the superconducting background, biaxial (checkerboard) charge order is energetically more favorable than uniaxial (stripe) charge order, and therefore checkerboard axial charge order should be the one observed in experiments, assuming a single domain of charge ordered state on each CuO2 plane.

  12. Photo-enhanced antinodal conductivity in the pseudogap state of high-Tc cuprates

    PubMed Central

    Cilento, F.; Dal Conte, S.; Coslovich, G.; Peli, S.; Nembrini, N.; Mor, S.; Banfi, F.; Ferrini, G.; Eisaki, H.; Chan, M. K.; Dorow, C. J.; Veit, M. J.; Greven, M.; van der Marel, D.; Comin, R.; Damascelli, A.; Rettig, L.; Bovensiepen, U.; Capone, M.; Giannetti, C.; Parmigiani, F.

    2014-01-01

    A major challenge in understanding the cuprate superconductors is to clarify the nature of the fundamental electronic correlations that lead to the pseudogap phenomenon. Here we use ultrashort light pulses to prepare a non-thermal distribution of excitations and capture novel properties that are hidden at equilibrium. Using a broadband (0.5–2 eV) probe, we are able to track the dynamics of the dielectric function and unveil an anomalous decrease in the scattering rate of the charge carriers in a pseudogap-like region of the temperature (T) and hole-doping (p) phase diagram. In this region, delimited by a well-defined T*neq(p) line, the photoexcitation process triggers the evolution of antinodal excitations from gapped (localized) to delocalized quasiparticles characterized by a longer lifetime. The novel concept of photo-enhanced antinodal conductivity is naturally explained within the single-band Hubbard model, in which the short-range Coulomb repulsion leads to a k-space differentiation between nodal quasiparticles and antinodal excitations. PMID:25014895

  13. A phenomenological description of an incoherent Fermi liquid near optimal doping in high Tc cuprates.

    PubMed

    Kim, Ki-Seok; Kim, Hyun-Chul

    2011-12-14

    Marginal Fermi-liquid physics near optimal doping in high T(c) cuprates has been explained within two competing scenarios such as the spin-fluctuation theory based on an itinerant picture and the slave-particle approach based on a localized picture. In this study we propose an alternative scenario for the anomalous transport within the context of the slave-particle approach. Although the marginal Fermi-liquid phenomenology was interpreted previously within deconfinement of the compact gauge theory, referred to as the strange metal phase, we start from confinement, introducing the Polyakov loop parameter into an SU(2) gauge theory formulation of the t-J model. The Polyakov loop parameter gives rise to incoherent electrons through the confinement of spinons and holons, which result from huge imaginary parts of self-energy corrections for spinons and holons. This confinement scenario serves a novel mechanism for the marginal Fermi-liquid transport in the respect that the scattering source has nothing to do with symmetry breaking. Furthermore, the incoherent Fermi-liquid state evolves into the Fermi-liquid phase through crossover instead of an artificial second-order transition as temperature is lowered, where the crossover phenomenon does not result from the Anderson-Higgs mechanism but originates from an energy scale in the holon sector. We fit experimental data for the electrical resistivity around the optimal doping and find a reasonable match between our theory and the experiment. PMID:22101360

  14. Synthesis and Magnetic, Thermal, and Electrical Measurements on Complex non-Cuprate Superconductors

    SciTech Connect

    Henry, Laurence L

    2006-02-27

    The project investigated superconductivity in non-cuprate materials with critical temperatures, T{sub c}, in excess of 20 K in order to understand the thermodynamics of several of these materials. The project is a cooperative effort between investigators at Southern University (SU), Louisiana State University (LSU), and Los Alamos National Laboratory (LANL). It involved synthesis of high quality samples, and subsequent detailed magnetic, thermal and electrical measurements on them. The project provided a PhD Thesis research experience and training for a graduate student, Ms. Robin Macaluso. High quality, single crystal samples were synthesized by Ms. Macaluso under the direction of one of the CO-PIS, John Sarao, during the summer while she was a visitor at LANL being supported by this grant. On these samples magnetic measurements were performed at SU, thermal and electrical measurements were made in the LSU Physics and Astronomy Department. The crystallographic properties were determined in the LSU Chemistry Department by Ms. Macaluso under the direction of her dissertation advisor, Dr. Julia Chan. Additional high field magnetic measurements on other samples were performed at the National High Magnetic Field Laboratory (NHMFL) both in Tallahassee and at LANL. These measurements involved another graduate student, Umit Alver, who used some of the measurements as part of his PhD dissertation in Physics at LSU.

  15. Interplay between uni-directional and bi-directional charge orders in underdoped cuprates

    NASA Astrophysics Data System (ADS)

    Wang, Yuxuan; Chubukov, Andrey

    We analyze the interplay between charge-density-wave (CDW) orders with axial momenta (Q , 0) and (0 , Q) (Δx and Δy respectively), detected in the underdoped cuprates. The CDW order in real space can be uni-directional (either Δx or Δy is non-zero) or bi-directional (both Δx and Δy are non-zero). To understand which of the two orders develop, we adopt the magnetic scenario, in which the CDW order appears due to spin-fluctuation exchange. We derive the Ginzburg-Landau action to the sixth order in Δx and Δy and argue that the CDW order is bi-directional at the onset but changes to uni-directional inside the CDW phase. This implies that, at a given temperature, CDW order is uni-directional at smaller dopings, but becomes bi-directional at larger dopings. These results are consistent with recent x-ray data on YBCO, which detected tendency towards bi-directional order at larger dopings. We also discuss for completeness the effect of yet unobserved intertwined pair-density-wave (PDW) order, which may appear along with CDW.

  16. The rate of quasiparticle recombination probes the onset of coherence in cuprate superconductors.

    PubMed

    Hinton, J P; Thewalt, E; Alpichshev, Z; Mahmood, F; Koralek, J D; Chan, M K; Veit, M J; Dorow, C J; Barišić, N; Kemper, A F; Bonn, D A; Hardy, W N; Liang, Ruixing; Gedik, N; Greven, M; Lanzara, A; Orenstein, J

    2016-01-01

    In the underdoped copper-oxides, high-temperature superconductivity condenses from a nonconventional metallic "pseudogap" phase that exhibits a variety of non-Fermi liquid properties. Recently, it has become clear that a charge density wave (CDW) phase exists within the pseudogap regime. This CDW coexists and competes with superconductivity (SC) below the transition temperature Tc, suggesting that these two orders are intimately related. Here we show that the condensation of the superfluid from this unconventional precursor is reflected in deviations from the predictions of BSC theory regarding the recombination rate of quasiparticles. We report a detailed investigation of the quasiparticle (QP) recombination lifetime, τqp, as a function of temperature and magnetic field in underdoped HgBa2CuO(4+δ) (Hg-1201) and YBa2Cu3O(6+x) (YBCO) single crystals by ultrafast time-resolved reflectivity. We find that τqp(T) exhibits a local maximum in a small temperature window near Tc that is prominent in underdoped samples with coexisting charge order and vanishes with application of a small magnetic field. We explain this unusual, non-BCS behavior by positing that Tc marks a transition from phase-fluctuating SC/CDW composite order above to a SC/CDW condensate below. Our results suggest that the superfluid in underdoped cuprates is a condensate of coherently-mixed particle-particle and particle-hole pairs. PMID:27071712

  17. Universal sheet resistance and revised phase diagram of the cuprate high-temperature superconductors

    PubMed Central

    Barišić, Neven; Chan, Mun K.; Li, Yuan; Yu, Guichuan; Zhao, Xudong; Dressel, Martin; Smontara, Ana; Greven, Martin

    2013-01-01

    Upon introducing charge carriers into the copper–oxygen sheets of the enigmatic lamellar cuprates, the ground state evolves from an insulator to a superconductor and eventually to a seemingly conventional metal (a Fermi liquid). Much has remained elusive about the nature of this evolution and about the peculiar metallic state at intermediate hole-carrier concentrations (p). The planar resistivity of this unconventional metal exhibits a linear temperature dependence (ρ ∝ T) that is disrupted upon cooling toward the superconducting state by the opening of a partial gap (the pseudogap) on the Fermi surface. Here, we first demonstrate for the quintessential compound HgBa2CuO4+δ a dramatic switch from linear to purely quadratic (Fermi liquid-like, ρ ∝ T2) resistive behavior in the pseudogap regime. Despite the considerable variation in crystal structures and disorder among different compounds, our result together with prior work gives insight into the p-T phase diagram and reveals the fundamental resistance per copper–oxygen sheet in both linear (ρ☐ = A1☐T) and quadratic (ρ☐ = A2☐T2) regimes, with A1☐ ∝ A2☐ ∝ 1/p. Theoretical models can now be benchmarked against this remarkably simple universal behavior. Deviations from this underlying behavior can be expected to lead to new insight into the nonuniversal features exhibited by certain compounds. PMID:23836669

  18. Sulfur Earth

    NASA Astrophysics Data System (ADS)

    de Jong, B. H.

    2007-12-01

    Variations in surface tension affect the buoyancy of objects floating in a liquid. Thus an object floating in water will sink deeper in the presence of dishwater fluid. This is a very minor but measurable effect. It causes for instance ducks to drown in aqueous solutions with added surfactant. The surface tension of liquid iron is very strongly affected by the presence of sulfur which acts as a surfactant in this system varying between 1.9 and 0.4 N/m at 10 mass percent Sulfur (Lee & Morita (2002), This last value is inferred to be the maximum value for Sulfur inferred to be present in the liquid outer core. Venting of Sulfur from the liquid core manifests itself on the Earth surface by the 105 to 106 ton of sulfur vented into the atmosphere annually (Wedepohl, 1984). Inspection of surface Sulfur emission indicates that venting is non-homogeneously distributed over the Earth's surface. The implication of such large variation in surface tension in the liquid outer core are that at locally low Sulfur concentration, the liquid outer core does not wet the predominantly MgSiO3 matrix with which it is in contact. However at a local high in Sulfur, the liquid outer core wets this matrix which in the fluid state has a surface tension of 0.4 N/m (Bansal & Doremus, 1986), couples with it, and causes it to sink. This differential and diapiric movement is transmitted through the essentially brittle mantle (1024 Pa.s, Lambeck & Johnson, 1998; the maximum value for ice being about 1030 Pa.s at 0 K, in all likely hood representing an upper bound of viscosity for all materials) and manifests itself on the surface by the roughly 20 km differentiation, about 0.1 % of the total mantle thickness, between topographical heights and lows with concomitant lateral movement in the crust and upper mantle resulting in thin skin tectonics. The brittle nature of the medium though which this movement is transmitted suggests that the extremes in topography of the D" layer are similar in range to

  19. Two-Dimensional Superconductivity in the Cuprates Revealed by Atomic-Layer-by- Layer Molecular Beam Epitaxy

    DOE PAGESBeta

    A. T. Bollinger; Bozovic, I.

    2016-08-12

    Various electronic phases displayed by cuprates that exhibit high temperature superconductivity continue to attract much interest. We provide a short review of several experiments that we have performed aimed at investigating the superconducting state in these compounds. Measurements on single-phase films, bilayers, and superlattices all point to the conclusion that the high-temperature superconductivity in these materials is an essentially quasi-two dimensional phenomenon. With proper control over the film growth, high-temperature superconductivity can exist in a single copper oxide plane with the critical temperatures as high as that achieved in the bulk samples.

  20. First observation for a cuprate superconductor of fluctuation-induced diamagnetism well inside the finite-magnetic-field regime

    PubMed

    Carballeira; Mosqueira; Revcolevschi; Vidal

    2000-04-01

    For the first time for a cuprate superconductor, measurements performed above T(c) in high quality grain aligned La1.9Sr0.1CuO4 samples have allowed the observation of the thermal fluctuation induced diamagnetism well inside the finite-magnetic-field fluctuation regime. These results may be explained in terms of the Gaussian Ginzburg-Landau approach for layered superconductors, but only if the finite field contributions are estimated by taking off the short-wavelength fluctuations. PMID:11019036

  1. Overview of recent magnetic studies of high T{sub c} cuprate parent compounds and related materials

    SciTech Connect

    Johnston, D.C.; Ami, T.; Borsa, F.

    1995-12-01

    Recent studies of the magnetic properties of several high superconducting transition temperature (T{sub c}) cuprate parent compounds and related materials will be reviewed. The observations of a Heisenberg to XY-like crossover upon cooling below {approximately}300K towards the Neel temperature T{sub N} = 257 K and a subsequent magnetic field-induced XY-like to Ising-like crossover near TN in single crystals of the K{sub 2}NiF{sub 4} type spin 1/2 model compound Sr{sub 2}CuO{sub 2}Cl{sub 2} will be described.

  2. Separation of charge-order and magnetic QCPs in heavy fermions and high Tc cuprates

    NASA Astrophysics Data System (ADS)

    Harrison, Neil

    2010-03-01

    The Fermi surface topology of high temperature superconductors inferred from magnetic quantum oscillation measurements provides clues for the origin of unconventional pairing thus previously not accessed by other spectroscopy techniques. While the overdoped regime of the high Tc phase diagram has a large Fermi surface consistent with bandstructure calculations, the underdoped regime of YBa2Cu2O6+x is found to be composed of small pockets. There is considerable debate as to whether the small observed ``pocket'' is hole-like or electron-like- whether the Fermi surface is best described by a t-J model or a conventional band folding picture- whether or not a Fermi liquid description applies- or- whether bilayer coupling splits the degeneracy of the observed pockets. We (myself and collaborators) have now collected an extensive body of experimental data that brings this debate to rest, but raises new questions about the nature of itinerant magnetism in underdoped high Tc cuprates. Quantum oscillation measurements are performed on multiple samples in magnetic fields extending to 85 T, temperatures between 30 mK (dilution fridge in dc fields to 45 T) and 18 K, over a range of hole dopings and with samples rotated in-situ about multiple axes with respect to the magnetic field. We perform a topographical map of the Fermi surface, enabling the in-plane shape of one of the pockets to be determined- imposing stringent constraints on the origin of the Fermi surface. While quantum oscillations measurements are consistent with a topological Fermi surface change associated with magnetism near optimal doping, they also point to a secondary instability deep within the underdoped regime beneath a high Tc superconducting sub-dome. An steep upturn in the quasiparticle effective mass is observed on underdoping, suggestive of a quantum critical point near x= 0.46 separating the metallic regime (composed of small pockets) from a more underdoped insulating charge-ordered regime (earlier

  3. Magnetization Studies of Oxides Related to the High Temperature Cuprate Superconductors

    NASA Astrophysics Data System (ADS)

    Wang, Zhaorong

    An Oxford Instruments Faraday magnetometer, capable of operating in the temperature range between 1.5 K and 1000 K, and magnetic field range between 0 T to 8 T, with a sensitivity of 3times10^{-8 }rm cm^3G, was assembled and calibrated. The pumping station which supported this magnetometer was designed and built. Software for reducing the raw data and generating calibration files was written. The magnetic properties of several oxides related to the high temperature cuprate superconductors BaCuO_{2+x}, La_2CuO_4, Sr _2IrO_4, Sr_2RhO_4, Sr_2VO _4, and Sr_2CuO_3 were measured using the Faraday magnetometer. AC and DC magnetization, neutron diffraction, and heat capacity measurements on polycrystalline BaCuO _{2+x} revealed a combination of magnetic behaviors. The Cu_6 ring clusters and Cu_{18}^here clusters in this compound were found to have ferromagnetic ground states with large spins 3 and 9, respectively. The Cu_6 rings ordered antiferromagnetically below the Neel temperature T_ N = 15 +/- 0.5 Kelvin, whereas the Cu _{18}^heres remained paramagnetic down to 2 Kelvin. The ordered moment below T_ N was 0.89(5) Bohr magnetons per Cu in the Cu_6 rings, demonstrating that quantum fluctuation effects are small in these atomic clusters. The Cu_{18} clusters are predicted to exhibit ferromagnetic intercluster order below about 1 Kelvin. Heat capacity C_ P data for BaCuO_{2+x} show a sharp second order transition at the Neel 2 temperature. The value of the discontinuity in the heat capacity at Neel is close to that expected for antiferromagnetic ordering of the ring clusters, according to the mean field theory. An additional maximum in C_ P at about 0.8 K may correspond to the ferromagnetic ordering of the sphere clusters postulated above. Understanding the magnetic behavior of BaCuO_{2+x } is relevant to the pairing mechanism in high T_ c cuprates. Magnetic susceptibility measurements for Sr _2CuO_{3+/-delta} were made from 2 K to 800 K, and a strong dependence upon

  4. Thermodynamic Critical Field and Superconducting Fluctuation of Vortices for High Temperature Cuprate Superconductor: La-214

    SciTech Connect

    Yung Moo Huh

    2001-05-01

    Thermodynamics has been studied systematically for the high temperature cuprate superconductor La{sub 2-x}Sr{sub x}CuO{sub 4-{delta}}, La-214, in the entire superconductive region from strongly underdoped to strongly overdoped regimes. Magnetization studies with H{parallel}c have been made in order to investigate the changes in free energy of the system as the number of carriers is reduced. Above the superconducting transition temperature, the normal-state magnetization exhibits a two-dimensional Heisenberg antiferromagnetic behavior. Below T{sub c}, magnetization data are thermodynamically reversible over large portions of the H-T plane, so the free energy is well defined in these regions. As the Sr concentration is varied over the wide range from 0.060 (strongly underdoped) to 0.234 (strongly overdoped), the free energy change goes through a maximum at the optimum doped in a manner similar to the T{sub c0} vs. x curve. The density of states, N(0), remains nearly constant in the overdoped and optimum doped regimes, taking a broad maximum around x = 0.188, and then drops abruptly towards zero in the underdoped regime. The La{sub 2-x}Sr{sub x}CuO{sub 4} (La-214) system displays the fluctuating vortex behavior with the characteristic of either 2D or 3D fluctuations as indicated by clearly identifiable crossing points T* close to T{sub c}. The dimensional character of the fluctuations depends on both applied magnetic fields and the density of charge carriers. The dimensional crossover from 2D to 3D occurs in the strongly underdoped regime when the c-axis coherence distance {zeta}{sub c} becomes comparable to the spacing between adjacent CuO{sub 2} layers s at sufficiently high magnetic fields near H{sub c2}.

  5. Quantitative determination of pairing interactions for high-temperature superconductivity in cuprates.

    PubMed

    Bok, Jin Mo; Bae, Jong Ju; Choi, Han-Yong; Varma, Chandra M; Zhang, Wentao; He, Junfeng; Zhang, Yuxiao; Yu, Li; Zhou, X J

    2016-03-01

    A profound problem in modern condensed matter physics is discovering and understanding the nature of fluctuations and their coupling to fermions in cuprates, which lead to high-temperature superconductivity and the invariably associated strange metal state. We report the quantitative determination of normal and pairing self-energies, made possible by laser-based angle-resolved photoemission measurements of unprecedented accuracy and stability. Through a precise inversion procedure, both the effective interactions in the attractive d-wave symmetry and the repulsive part in the full symmetry are determined. The latter is nearly angle-independent. Near T c, both interactions are nearly independent of frequency and have almost the same magnitude over the complete energy range of up to about 0.4 eV, except for a low-energy feature at around 50 meV that is present only in the repulsive part, which has less than 10% of the total spectral weight. Well below T c, they both change similarly, with superconductivity-induced features at low energies. Besides finding the pairing self-energy and the attractive interactions for the first time, these results expose the central paradox of the problem of high T c: how the same frequency-independent fluctuations can dominantly scatter at angles ±π/2 in the attractive channel to give d-wave pairing and lead to angle-independent repulsive scattering. The experimental results are compared with available theoretical calculations based on antiferromagnetic fluctuations, the Hubbard model, and quantum-critical fluctuations of the loop-current order. PMID:26973872

  6. Formation and properties of novel artificially-layered cuprate superconductors using pulsed-laser deposition

    SciTech Connect

    Norton, D.P.; Chakoumakos, B.C.; Budai, J.D.

    1996-03-01

    Pulsed-laser deposition and epitaxial stabilization have been effectively used to engineer artificially-layered thin-film materials. Novel cuprate compounds have been synthesized using the constraint of epitaxy to stabilize (Ca,Sr)CuO{sub 2}/(Ba,Ca,Sr)CuO{sub 2} superconducting superlattices in the infinite layer structure. Superlattice chemical modulation can be observed from the x-ray diffraction patterns for structures with SrCuO{sub 2} and (Ca, Sr)CuO{sub 2} layers as thin as a single unit cell ({approximately}3. 4 {angstrom}). X-ray diffraction intensity oscillations, due to the finite thickness of the film, indicate that (Ca,Sr)CuO{sub 2} films grown by pulsed-laser deposition are extremely flat with a thickness variation of only {approximately}20 {angstrom} over a length scale of several thousand angstroms. This enables the unit-cell control of (Ca, Sr)CuO{sub 2} film growth in an oxygen pressure regime in which in situ surface analysis using electron diffraction is not possible. With the incorporation of BaCuO{sub 2} layers, superlattice structures have been synthesized which superconduct at temperatures as high as 70 K. Dc transport measurements indicate that (Ca, Sr)CuO{sub 2}/BaCuO{sub 2} superlattices are two dimensional superconductors with the superconducting transition primarily associated with the BaCuO{sub 2} layers. Superconductivity is observed only for structures with BaCuO{sub 2} layers at least two unit cells thick with {Tc} decreasing as the (Ca,Sr)CuO{sub 2} layer thickness increases. Normalized resistance in the superconducting region collapse to the Ginzburg-Landau Coulomb gas universal resistance curve consistent with the two-dimensional vortex fluctuation model.

  7. Isotropic round-wire multifilament cuprate superconductor for generation of magnetic fields above 30 T.

    PubMed

    Larbalestier, D C; Jiang, J; Trociewitz, U P; Kametani, F; Scheuerlein, C; Dalban-Canassy, M; Matras, M; Chen, P; Craig, N C; Lee, P J; Hellstrom, E E

    2014-04-01

    Magnets are the principal market for superconductors, but making attractive conductors out of the high-temperature cuprate superconductors (HTSs) has proved difficult because of the presence of high-angle grain boundaries that are generally believed to lower the critical current density, J(c). To minimize such grain boundary obstacles, HTS conductors such as REBa2Cu3O(7-x) and (Bi, Pb)2Sr2Ca2Cu3O(10-x) are both made as tapes with a high aspect ratio and a large superconducting anisotropy. Here we report that Bi2Sr2CaCu2O(8-x) (Bi-2212) can be made in the much more desirable isotropic, round-wire, multifilament form that can be wound or cabled into arbitrary geometries and will be especially valuable for high-field NMR magnets beyond the present 1 GHz proton resonance limit of Nb3Sn technology. An appealing attribute of this Bi-2212 conductor is that, being without macroscopic texture, it contains many high-angle grain boundaries but nevertheless attains a very high J(c) of 2,500 A mm(-2) at 20 T and 4.2 K. The large potential of the conductor has been demonstrated by building a small coil that generated almost 2.6 T in a 31 T background field. This demonstration that grain boundary limits to high Jc can be practically overcome underlines the value of a renewed focus on grain boundary properties in non-ideal geometries. PMID:24608141

  8. Quantitative determination of pairing interactions for high-temperature superconductivity in cuprates

    PubMed Central

    Bok, Jin Mo; Bae, Jong Ju; Choi, Han-Yong; Varma, Chandra M.; Zhang, Wentao; He, Junfeng; Zhang, Yuxiao; Yu, Li; Zhou, X. J.

    2016-01-01

    A profound problem in modern condensed matter physics is discovering and understanding the nature of fluctuations and their coupling to fermions in cuprates, which lead to high-temperature superconductivity and the invariably associated strange metal state. We report the quantitative determination of normal and pairing self-energies, made possible by laser-based angle-resolved photoemission measurements of unprecedented accuracy and stability. Through a precise inversion procedure, both the effective interactions in the attractive d-wave symmetry and the repulsive part in the full symmetry are determined. The latter is nearly angle-independent. Near Tc, both interactions are nearly independent of frequency and have almost the same magnitude over the complete energy range of up to about 0.4 eV, except for a low-energy feature at around 50 meV that is present only in the repulsive part, which has less than 10% of the total spectral weight. Well below Tc, they both change similarly, with superconductivity-induced features at low energies. Besides finding the pairing self-energy and the attractive interactions for the first time, these results expose the central paradox of the problem of high Tc: how the same frequency-independent fluctuations can dominantly scatter at angles ±π/2 in the attractive channel to give d-wave pairing and lead to angle-independent repulsive scattering. The experimental results are compared with available theoretical calculations based on antiferromagnetic fluctuations, the Hubbard model, and quantum-critical fluctuations of the loop-current order. PMID:26973872

  9. Thermodynamic Critical Field and Superconducting Fluctuation of Vortices for High Temperature Cuprate Superconductor: La-214

    SciTech Connect

    Douglas K. Finnemore

    2001-06-25

    Thermodynamics has been studied systematically for the high temperature cuprate superconductor La{sub 2-x}Sr{sub x}CuO{sub 4-{delta}}, La-214, in the entire superconductive region from strongly underdoped to strongly overdoped regimes. Magnetization studies with H {parallel} c have been made in order to investigate the changes in free energy of the system as the number of carriers is reduced. Above the superconducting transition temperature, the normal-state magnetization exhibits a two-dimensional Heisenberg antiferromagnetic behavior. Below T{sub c}, magnetization data are thermodynamically reversible over large portions of the H-T plane, so the free energy is well defined in these regions. As the Sr concentration is varied over the wide range from 0.060 (strongly underdoped) to 0.234 (strongly overdoped), the free energy change goes through a maximum at the optimum doped in a manner similar to the T{sub c0} vs. x curve. The density of states, N(0), remains nearly constant in the overdoped and optimum doped regimes, taking a broad maximum around x = 0.188, and then drops abruptly towards zero in the underdoped regime. The La{sub 2-x}Sr{sub x}CuO{sub 4} (La-214) system displays the fluctuating vortex behavior with the characteristic of either 2D or 3D fluctuations as indicated by clearly identifiable crossing points T* close to T{sub c}. The dimensional character of the fluctuations depends on both applied magnetic fields and the density of charge carriers. The dimensional crossover from 2D to 3D occurs in the strongly underdoped regime when the c-axis coherence distance {xi}{sub c} becomes comparable to the spacing between adjacent CuO{sub 2} layers s at sufficiently high magnetic field near H{sub c2}.

  10. Earth Observation

    NASA Technical Reports Server (NTRS)

    1994-01-01

    For pipeline companies, mapping, facilities inventory, pipe inspections, environmental reporting, etc. is a monumental task. An Automated Mapping/Facilities Management/Geographic Information Systems (AM/FM/GIS) is the solution. However, this is costly and time consuming. James W. Sewall Company, an AM/FM/GIS consulting firm proposed an EOCAP project to Stennis Space Center (SSC) to develop a computerized system for storage and retrieval of digital aerial photography. This would provide its customer, Algonquin Gas Transmission Company, with an accurate inventory of rights-of-way locations and pipeline surroundings. The project took four years to complete and an important byproduct was SSC's Digital Aerial Rights-of-Way Monitoring System (DARMS). DARMS saves substantial time and money. EOCAP enabled Sewall to develop new products and expand its customer base. Algonquin now manages regulatory requirements more efficiently and accurately. EOCAP provides government co-funding to encourage private investment in and broader use of NASA remote sensing technology. Because changes on Earth's surface are accelerating, planners and resource managers must assess the consequences of change as quickly and accurately as possible. Pacific Meridian Resources and NASA's Stennis Space Center (SSC) developed a system for monitoring changes in land cover and use, which incorporated the latest change detection technologies. The goal of this EOCAP project was to tailor existing technologies to a system that could be commercialized. Landsat imagery enabled Pacific Meridian to identify areas that had sustained substantial vegetation loss. The project was successful and Pacific Meridian's annual revenues have substantially increased. EOCAP provides government co-funding to encourage private investment in and broader use of NASA remote sensing technology.

  11. Doping evolution of the electronic structure in the single-layer cuprates Bi2Sr2−xLaxCuO6 delta: Comparison with other single-layer cuprates

    SciTech Connect

    Hashimoto, M.

    2010-04-30

    We have performed angle-resolved photoemission and core-level x-ray photoemission studies of the single-layer cuprate Bi{sub 2}Sr{sub 2-x}La{sub x}CuO{sub 6+{delta}} (Bi2201) and revealed the doping evolution of the electronic structure from the lightly-doped to optimally-doped regions. We have observed the formation of the dispersive quasi-particle band, evolution of the Fermi 'arc' into the Fermi surface and the shift of the chemical potential with hole doping as in other cuprates. The doping evolution in Bi2201 is similar to that in Ca{sub 2-x}Na{sub x}CuO{sub 2}Cl{sub 2} (Na-CCOC), where a rapid chemical potential shift toward the lower Hubbard band of the parent insulator has been observed, but is quite different from that in La{sub 2-x}Sr{sub x}CuO{sub 4} (LSCO), where the chemical potential does not shift, yet the dispersive band and the Fermi arc/surface are formed around the Fermi level already in the lightly-doped region. The (underlying) Fermi surface shape and band dispersions are quantitatively analyzed using tightbinding fit, and the deduced next-nearest-neighbor hopping integral t also confirm the similarity to Na-CCOC and the difference from LSCO.

  12. The Lifeworld Earth and a Modelled Earth

    NASA Astrophysics Data System (ADS)

    Juuti, Kalle

    2014-08-01

    The goal of this paper is to study the question of whether a phenomenological view of the Earth could be empirically endorsed. The phenomenological way of thinking considers the Earth as a material entity, but not as an object as viewed in science. In the learning science tradition, tracking the process of the conceptual change of the shape of the Earth, science's view of the Earth as an object—a celestial body—has been applied. I reanalysed data published in Vosniadou and Brewer's (Cognit psychol 24:535-585, 1992) seminal paper. According to my reanalysis of their interview material, it is plausible to conclude that the Earth as an infinite surface is the way to experience the Earth. Further, the `dual Earth model' is the first model of the Earth as an object. I conclude that experiences in the lifeworld need to be taken into consideration more seriously in science education research.

  13. Possible Room-Tc Superconductor with in-plane Ginzburg Sandwichin Cuprate-and Pnictide-likefamilyof Compounds

    NASA Astrophysics Data System (ADS)

    Mazov, L. S.

    On the basis of detailed analysis of resistive, neutron and optical experimental data in doped cuprates it is demonstrated that high critical temperature Tc of superconducting transition in these compounds is provided by Cooper pairing of mobile charge carriers in conducting charge (C) stripes due to delocalized, in-plane, charge-transfer (CT) excitons, propagating in semi-insulating spin (S) stripes, adjacent with C-ones. Such stripe structure arises in the pseudogap state in result of magnetic phase transition from spin-disordered state to magnetically-ordered one, like to incommensurate: T:Tonset SDW in CuO2 planes at Tonset ≤ T', which transition is accompanied by opening of the SDW-gap c SDW (pseudogap) at symmetrical parts of the Fermi surface. So-formed SDWstate, because of its incommensurability with the lattice period, generates the CDWwith wavelength ACDW = AS DW/2and, hence, the wave of lattice distortion. The crucial rise of Tc in cuprates duetoexcitonsis precededby moderate riseof Tc due to phonons, characteristic for partial dielectrization of electron energy spectrum in itinerant electron systems with interplay between superconductivity and magnetism. The picture is consistent with the Little-Ginzburg(LG) exciton mechanism of high-Tc superconductivity in planar geometry of GinzburgHTS-sandwich: insulator-metal-insulator. The new way to synthesize room-Tc supercon-ductors(RTS)in similar transitional-metal compounds with higher energyof in-planeCT transitionis proposed.

  14. Phenomenology of the valence-fluctuation pairing mechanism: {Tc} systematics of cuprates, and evidence for this mechanism in other superconductors

    SciTech Connect

    Brandow, B.H.

    1994-12-15

    The phenomenology of the cuprate superconductors is unconventional in many respects, in addition to the high {Tc}`s. A number of these features have recently been explained, qualitatively and even semi-quantitatively, by means of a valence-fluctuation mechanism. They now examine the extent to which this mechanism can account, at a qualitative level, for the {Tc} systematics of the many known cuprate superconductors. They find that this mechanism is consistent with some major features of the {Tc} systematics: the strong dependence on the hole-doping concentration x, the strong correlation with the Madelung potential of the apical oxygens, and a strong dependence on the number of apical oxygens per planar copper ion. They also argue that the same mechanism should be operating (together with phonons) in a number of other superconductors, in particular in the other exotic superconductors of Uemura. The evidence is that typical features of these exotics include extremely short coherence length, very high (and often T{sup 2}) normal-state resistivity, a highly anomalous form of H{sub c2}(T), a large London penetration depth, and an often obvious suitability for representation by an Anderson lattice form of model Hamiltonian. The frequently-encountered cluster and/or reduced-dimensionality aspects are argued to be features which help to justify the latter form of model Hamiltonian. 81 refs.

  15. Frank Isakson Prize Talk: Superfluid and normal-fluid densities in the cuprate superconductors from infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Tanner, D. B.

    Measurements for a number of cuprate families of optical reflectance over a wide spectral range (far-infrared to ultraviolet) have been analyzed using Kramers-Kronig analysis to obtain the optical conductivity σ (ω) and (by integration of the real part of the conductivity) the spectral weight of low- and mid-energy excitations. For the Kramers-Kronig analysis to give reliable results, accurate high-frequency extrapolations, based on x-ray atomic scattering functions, were used. When the optical conductivities of the normal and superconducting states are compared, a transfer of spectral weight from finite frequencies to the zero-frequency delta-function conductivity of the superconductor is seen. The strength of this delta function gives the superfluid density, ρs. In a clean metallic superconductor the superfluid density is essentially equal to the conduction electron density. The cuprates in contrast have only about 20% of the a b-plane low-energy spectral weight in the superfluid. The rest remains in finite-frequency, midinfrared absorption. In underdoped materials the superfluid fraction is even smaller. There are two ways to measure ρs, using either the partial sum rule for the conductivity or by examination of σ2 (ω) . Comparison of these two estimates of the superfluid density shows that 98% of the a b-plane superfluid density comes from energies below 0.15 eV. Many students, postdocs, and materials preparers have contributed to this work; to all I am very grateful.

  16. Nodal bilayer-splitting controlled by spin-orbit interactions in underdoped high-Tc cuprates

    SciTech Connect

    Harrison, N.; Ramshaw, B. J.; Shekhter, A.

    2015-06-03

    The highest superconducting transition temperatures in the cuprates are achieved in bilayer and trilayer systems, highlighting the importance of interlayer interactions for high Tc. It has been argued that interlayer hybridization vanishes along the nodal directions by way of a specific pattern of orbital overlap. Recent quantum oscillation measurements in bilayer cuprates have provided evidence for a residual bilayer-splitting at the nodes that is sufficiently small to enable magnetic breakdown tunneling at the nodes. Here we show that several key features of the experimental data can be understood in terms of weak spin-orbit interactions naturally present in bilayer systems, whose primary effect is to cause the magnetic breakdown to be accompanied by a spin flip. These features can now be understood to include the equidistant set of three quantum oscillation frequencies, the asymmetry of the quantum oscillation amplitudes in c-axis transport compared to ab-plane transport, and the anomalous magnetic field angle dependence of the amplitude of the side frequencies suggestive of small effective g-factors. We suggest that spin-orbit interactions in bilayer systems can further affect the structure of the nodal quasiparticle spectrum in the superconducting phase. PACS numbers: 71.45.Lr, 71.20.Ps, 71.18.+y

  17. Thermodynamic and nonstoichiometric behavior of promising Hi-Tc cuprate systems via EMF measurements : a short review.

    SciTech Connect

    Tetenbaum, M.

    1999-02-24

    Electromotive force (EMF) measurements of oxygen fugacities as a function of stoichiometry have been made on the YBa{sub 2}Cu{sub 3}O{sub x}, GdBa{sub 2}Cu{sub 3}O{sub x}, NdBa{sub 2}Cu{sub 3}O{sub x} and bismuth cuprate systems in the temperature range {approximately}400-750 C by means of an oxygen titration technique with an yttria-stabilized zirconia electrolyte. The shapes of the 400 C isotherms as a function of oxygen stoichiometry for the Gd and Nd cuprate systems suggest the presence of miscibility gaps at values of x that are higher than those in the YBa{sub 2}Cu{sub 3}O{sub x} system. For a given oxygen stoichiometry, oxygen partial pressures above GdBa{sub 2}Cu{sub 3}O{sub x} and NdBa{sub 2}Cu{sub 3}O{sub x} are higher (above x=6.5) than that for the promising YBa{sub 2}Cu{sub 3}O{sub x} system. A thermodynamic assessment and intercomparison of our partial pressure measurements with the results of related measurements will be presented.

  18. Two-component energy spectrum of cuprates in the pseudogap phase and its evolution with temperature and at charge ordering

    PubMed Central

    Gor'kov, Lev P.; Teitel'baum, Gregory B.

    2015-01-01

    In the search for mechanisms of high-temperature superconductivity it is critical to know the electronic spectrum in the pseudogap phase from which superconductivity evolves. The lack of angle-resolved photoemission data for every cuprate family precludes an agreement as to its structure, doping and temperature dependence and the role of charge ordering. Here we show that, in the entire Fermi-liquid-like regime that is ubiquitous in underdoped cuprates, the spectrum consists of holes on the Fermi arcs and an electronic pocket. We argue that experiments on the Hall coefficient identify the latter as a permanent feature at doped hole concentration x > 0.08–0.10, in contrast to the idea of the Fermi surface reconstruction via charge ordering. The longstanding issue of the origin of the negative Hall coefficient in YBCO and Hg1201 at low temperature is resolved: the electronic contribution prevails as mobility of the latter (evaluated by the Dingle temperature) becomes temperature independent, while the mobility of holes scattered by the short-wavelength charge density waves decreases. PMID:25688011

  19. Two-component energy spectrum of cuprates in the pseudogap phase and its evolution with temperature and at charge ordering.

    PubMed

    Gor'kov, Lev P; Teitel'baum, Gregory B

    2015-01-01

    In the search for mechanisms of high-temperature superconductivity it is critical to know the electronic spectrum in the pseudogap phase from which superconductivity evolves. The lack of angle-resolved photoemission data for every cuprate family precludes an agreement as to its structure, doping and temperature dependence and the role of charge ordering. Here we show that, in the entire Fermi-liquid-like regime that is ubiquitous in underdoped cuprates, the spectrum consists of holes on the Fermi arcs and an electronic pocket. We argue that experiments on the Hall coefficient identify the latter as a permanent feature at doped hole concentration x > 0.08-0.10, in contrast to the idea of the Fermi surface reconstruction via charge ordering. The longstanding issue of the origin of the negative Hall coefficient in YBCO and Hg1201 at low temperature is resolved: the electronic contribution prevails as mobility of the latter (evaluated by the Dingle temperature) becomes temperature independent, while the mobility of holes scattered by the short-wavelength charge density waves decreases. PMID:25688011

  20. Local structural studies of oriented high-temperature superconducting cuprates by polarized XAFS spectroscopy

    NASA Astrophysics Data System (ADS)

    Haskel, Daniel

    1998-07-01

    Doping (Sr,Ba) in Lasb{2-x}(Sr,Ba)sb{x}CuOsb4 induces high Tsb{c} superconductivity in addition to profound changes in structural, magnetic and normal state electronic properties. The purpose of this thesis is to investigate the structural characteristics accompanying this doping by performing orientation dependent x-ray absorption fine structure (XAFS) measurements on magnetically aligned powders. This type of measurements allowed obtaining critical information at the La/(Sr,Ba) site previously unavailable, as detailed below. The measurements show that hole carriers introduced with Sr are polaronic in nature as evident from the two site configuration found for the O(2) apical neighboring Sr and the lack of temperature dependence in the O(2) distribution, which indicates that the hole states associated with each site are not discrete but rather broader than ksb{B}T up to T = 300K. There is a good theoretical argument suggesting each O(2) site is associated with holes being doped into O(1) 2psb{x,y}-Cu 3dsb{xsp2-ysp2} in-plane and O(2) 2psb{z}-Cu 3dsb{3zsp2-rsp2} out-of-plane electronic bands resulting in two different Jahn-Teller distortions of the CuOsb6 octahedra neighboring Sr, where the doped holes are peaked. Based on this argument, the predominance of out-of-plane character for the doped holes, as evidenced from the concentration dependence of the relative population of O(2) sites, would imply that theories of high Tsb{c} relying only on in-plane character of the doped holes are not complete in describing the properties of these cuprates. Our measurements showed that all structural phase transitions in Lasb{2-x}(Sr,Ba)sb{x}CuOsb4 have a significant order-disorder component, as opposed to the purely displacive models found in crystallographic studies. The CuOsb6 octahedra are locally tilted in the high-doping, high-temperature phases but fail to order over long range resulting in the average structures of the crystallographic studies. A critical parameter in

  1. Normal-state conductivity of underdoped to overdoped cuprate superconductors: Pseudogap effects on the in-plane and c-axis charge transports

    NASA Astrophysics Data System (ADS)

    Dzhumanov, S.; Ganiev, O. K.; Djumanov, Sh. S.

    2014-05-01

    We have developed a theory of the unusual in-plane and c-axis charge transports in hole-doped cuprate superconductors and explain the temperature- and doping-dependent in-plane resistivity ρab, c-axis resistivity ρc and resistivity anisotropy ρc/ρab seen experimentally above Tc. We argue that the relevant current carriers in these materials above Tc are hole-like. The in-plane conductivity of underdoped to overdoped cuprates is considered as the conductivity of hole polarons and preformed Cooper pairs at their scattering by lattice vibrations in hole-rich CuO2 layers (with nonzero thickness). The appropriate Boltzmann transport equations were used to calculate the conductivity of polaronic carriers and bosonic Cooper pairs above and below the pseudogap (PG) temperature T* in the relaxation time approximation. We show that the linearity of ρab(T) above T* is associated with the polaron-phonon scattering, while different deviations from the T-linear behavior in ρab(T) below T* are caused by transition to the BCS-like PG regime. The specific model for layered cuprates is used to simulate the c-axis transport and to calculate the c-axis conductivity associated with the thermal dissociation of localized bipolarons in carrier-poor regions between the CuO2 layers into hole polarons which subsequently move by hopping along the c-axis. It is shown that the bipolaronic PG and carrier-confinement together cause the insulating ρc(T) behavior in the cuprates. The calculated results for ρab(T), ρc(T) and ρc(T)/ρab(T) were compared with the experimental data obtained for various hole-doped cuprates. For all the considered cases, a good quantitative agreement was found between theory and experimental data.

  2. Why Earth Science?

    ERIC Educational Resources Information Center

    Smith, Michael J.

    2004-01-01

    This article briefly describes Earth science. The study of Earth science provides the foundation for an understanding of the Earth, its processes, its resources, and its environment. Earth science is the study of the planet in its entirety, how its lithosphere, atmosphere, hydrosphere, and biosphere work together as systems and how they affect…

  3. Crew Earth Observations

    NASA Technical Reports Server (NTRS)

    Runco, Susan

    2009-01-01

    Crew Earth Observations (CEO) takes advantage of the crew in space to observe and photograph natural and human-made changes on Earth. The photographs record the Earth's surface changes over time, along with dynamic events such as storms, floods, fires and volcanic eruptions. These images provide researchers on Earth with key data to better understand the planet.

  4. Earth Observing System, Introduction

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Much is known about the Earth, but the unifying concepts are still only beginning to be established. An exposition of the key issues in Earth science is neither simple or concise. From the scientific questions at hand there are many interconnections among them and the view of the Earth as a system is essential to their solution. The Earth science goals for the 1990's are presented for the following areas: hydrologic cycle; biogeochemical cycles; climatological processes; geophysical processes; oceanography; and solid earth.

  5. Quantum-critical fluctuations in 2D metals: strange metals and superconductivity in antiferromagnets and in cuprates.

    PubMed

    Varma, Chandra M

    2016-08-01

    The anomalous transport and thermodynamic properties in the quantum-critical region, in the cuprates, and in the quasi-two dimensional Fe-based superconductors and heavy-fermion compounds, have the same temperature dependences. This can occur only if, despite their vast microscopic differences, a common statistical mechanical model describes their phase transitions. The antiferromagnetic (AFM)-ic models for the latter two, just as the loop-current model for the cuprates, map to the dissipative XY model. The solution of this model in (2+1)D reveals that the critical fluctuations are determined by topological excitations, vortices and a variety of instantons, and not by renormalized spin-wave theories of the Landau-Ginzburg-Wilson type, adapted by Moriya, Hertz and others for quantum-criticality. The absorptive part of the fluctuations is a separable function of momentum [Formula: see text], measured from the ordering vector, and of the frequency ω and the temperature T which scale as [Formula: see text] at criticality. Direct measurements of the fluctuations by neutron scattering in the quasi-two-dimensional heavy fermion and Fe-based compounds, near their antiferromagnetic quantum critical point, are consistent with this form. Such fluctuations, together with the vertex coupling them to fermions, lead to a marginal fermi-liquid, with the imaginary part of the self-energy [Formula: see text] for all momenta, a resistivity [Formula: see text], a [Formula: see text] contribution to the specific heat, and other singular fermi-liquid properties common to these diverse compounds, as well as to d-wave superconductivity. This is explicitly verified, in the cuprates, by analysis of the pairing and the normal self-energy directly extracted from the recent high resolution angle resolved photoemission measurements. This reveals, in agreement with the theory, that the frequency dependence of the attractive irreducible particle-particle vertex in the d-wave channel is the same

  6. Quantum-critical fluctuations in 2D metals: strange metals and superconductivity in antiferromagnets and in cuprates

    NASA Astrophysics Data System (ADS)

    Varma, Chandra M.

    2016-08-01

    The anomalous transport and thermodynamic properties in the quantum-critical region, in the cuprates, and in the quasi-two dimensional Fe-based superconductors and heavy-fermion compounds, have the same temperature dependences. This can occur only if, despite their vast microscopic differences, a common statistical mechanical model describes their phase transitions. The antiferromagnetic (AFM)-ic models for the latter two, just as the loop-current model for the cuprates, map to the dissipative XY model. The solution of this model in (2+1)D reveals that the critical fluctuations are determined by topological excitations, vortices and a variety of instantons, and not by renormalized spin-wave theories of the Landau–Ginzburg–Wilson type, adapted by Moriya, Hertz and others for quantum-criticality. The absorptive part of the fluctuations is a separable function of momentum \\mathbf{q} , measured from the ordering vector, and of the frequency ω and the temperature T which scale as \\tanh (ω /2T) at criticality. Direct measurements of the fluctuations by neutron scattering in the quasi-two-dimensional heavy fermion and Fe-based compounds, near their antiferromagnetic quantum critical point, are consistent with this form. Such fluctuations, together with the vertex coupling them to fermions, lead to a marginal fermi-liquid, with the imaginary part of the self-energy \\propto \\text{max}(ω,T) for all momenta, a resistivity \\propto T , a T\\ln T contribution to the specific heat, and other singular fermi-liquid properties common to these diverse compounds, as well as to d-wave superconductivity. This is explicitly verified, in the cuprates, by analysis of the pairing and the normal self-energy directly extracted from the recent high resolution angle resolved photoemission measurements. This reveals, in agreement with the theory, that the frequency dependence of the attractive irreducible particle–particle vertex in the d-wave channel is the same as the irreducible

  7. Two types of nematicity in the phase diagram of the cuprate superconductor YBa2Cu3Oy

    NASA Astrophysics Data System (ADS)

    Cyr-Choinière, O.; Grissonnanche, G.; Badoux, S.; Day, J.; Bonn, D. A.; Hardy, W. N.; Liang, R.; Doiron-Leyraud, N.; Taillefer, Louis

    2015-12-01

    Nematicity has emerged as a key feature of cuprate superconductors, but its link to other fundamental properties such as superconductivity, charge order, and the pseudogap remains unclear. Here we use measurements of transport anisotropy in YBa2Cu3Oy to distinguish two types of nematicity. The first is associated with short-range charge-density-wave modulations in a doping region near p =0.12 . It is detected in the Nernst coefficient, but not in the resistivity. The second type prevails at lower doping, where there are spin modulations but no charge modulations. In this case, the onset of in-plane anisotropy—detected in both the Nernst coefficient and the resistivity—follows a line in the temperature-doping phase diagram that tracks the pseudogap energy. We discuss two possible scenarios for the latter nematicity.

  8. Short-ranged and short-lived charge-density-wave order and pseudogap features in underdoped cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Greco, Andrés; Bejas, Matías

    2011-06-01

    The pseudogap phase of high-Tc cuprates is controversially attributed to preformed pairs or to a phase which coexists and competes with superconductivity. One of the challenges is to develop theoretical and experimental studies in order to distinguish between both proposals. Very recently, researchers at Stanford have reported [M. Hashimoto , Nat. Phys.PRLTAO1745-247310.1038/nphys1632 6, 414 (2010); R.-H. He , ScienceSCIEAS0036-807510.1126/science.1198415 331, 1579 (2011)] angle-resolved photoemission spectroscopy experiments on Pb-Bi2201 supporting the point of view that the pseudogap is distinct from superconductivity and associated to a spacial symmetry breaking without long-range order. In this paper, we show that many features reported by these experiments can be described in the framework of the t-J model considering self-energy effects in the proximity to a d charge-density-wave instability.

  9. Optical conductivity of cuprates in the pseudogap state: Yang-Rice-Zhang model and antiferromagnetic spin waves

    SciTech Connect

    Singh, Navinder; Sharma, Raman

    2015-05-15

    In the underdoped regime of the cuprate phase diagram, the modified version of the Resonance Valence Bond (RVB) model by Yang, Rice and Zhang (YRZ) captures the strong electronic correlation effects very well as corroborated by the ARPES and many other experiments. However, under a non-equilibrium transport setting, YRZ says nothing about the scattering mechanisms of the charge carriers. In the present investigation we include, in a very simplified way, the scattering of charge carriers due to antiferromagnetic type spin waves (ASW). The effect of ASW excitations on conductivity has been studied by changing combined life times of the included process. It has been found that there is a qualitative change in the conductivity in the right direction. The theoretical conductivity reproduces qualitatively the experimental one.

  10. The roles of antiferromagnetic and nematic fluctuations in cuprate superconductors: a sign-free quantum Monte-Carlo study

    NASA Astrophysics Data System (ADS)

    Li, Zixiang; Yao, Hong; Wang, Fa; Lee, Dung-Hai

    Superconductivity is an emergent phenomena in the sense that the energy scale at which Cooper pairs form is generically much lower than the bare energy scale, namely the electron kinetic energy bandwidth. Addressing the mechanism of Cooper pairing amounts to finding out the effective interaction (or the renormalized interaction) that operates at the low energies. Finding such interaction from the bare microscopic Hamiltonian has not been possible for strong correlated superconductors such as the copper-oxide high temperature superconductor. In fact even one is given the effective interaction, determining its implied electronic instabilities without making any approximation has been a formidable task. Here, we perform sign-free quantum Monte-Carlo simulations to study the antiferromagnetic, superconducting, and the charge density wave instabilities which are ubiquitous in both electron and hole doped cuprates. Our result suggests only after including both the nematic and antiferromagnetic fluctuation, are the observed properties associated with these instabilities reproduced by the theory.

  11. Anomalous electronic susceptibility in Bi2Sr2CuO6+δ and comparison with other overdoped cuprates

    NASA Astrophysics Data System (ADS)

    Le Bras, G.; Konstantinovic, Z.; Colson, D.; Forget, A.; Carton, J.-P.; Ayache, C.; Jean, F.; Collin, G.; Dumont, Y.

    2002-11-01

    We report magnetic susceptibility performed on overdoped Bi2Sr2CuO6+δ powders as a function of oxygen doping δ and temperature T. The decrease of the spin susceptibility χs with increasing T is confirmed. At sufficiently high temperature, χs presents an unusual linear temperature dependence χs~χs0-χ1T. Moreover, a linear correlation between χ1 and χs0 for increasing hole concentration is displayed. A temperature Tχ=(dχs0/dχ1) independent of hole doping characterizes this scaling. Comparison with other cuprates of the literature (La2-xSrxCuO4, Tl2Ba2CuO6+δ, and Bi2Sr2CaCu2O8+δ), over the same overdoped range, shows similarities with above results. These nonconventional metal features will be discussed in terms of a singular narrow-band structure.

  12. Light-induced enhancement of superconductivity via melting of competing bond-density wave order in underdoped cuprates

    NASA Astrophysics Data System (ADS)

    Patel, Aavishkar A.; Eberlein, Andreas

    2016-05-01

    We develop a theory for light-induced superconductivity in underdoped cuprates in which the competing bond-density wave order is suppressed by driving phonons with light. Close to a bond-density wave instability in a system with a small Fermi surface, such as a fractionalized Fermi liquid, we show that the coupling of electrons to phonons is strongly enhanced at the bond-density wave ordering wave vectors, leading to a strong softening of phonons at these wave vectors. For a model of classical phonons with anharmonic couplings, we show that the combination of strong softening and driving can lead to large phonon oscillations. When coupled to a phenomenological model describing the competition between bond-density wave order and superconductivity, these phonon oscillations melt bond-density wave order, thereby enhancing pairing correlations.

  13. Angle-resolved photoemission studies of lattice polaron formation in the cuprate Ca2CuO2Cl2

    SciTech Connect

    Shen, K.M.

    2010-05-03

    To elucidate the nature of the single-particle excitations in the undoped parent cuprates, we have performed a detailed study of Ca{sub 2}CuO{sub 2}Cl{sub 2} using photoemission spectroscopy. The photoemission lineshapes of the lower Hubbard band are found to be well-described by a polaron model. By comparing the lineshape and temperature dependence of the lower Hubbard band with additional O 2p and Ca 3p states, we conclude that the dominant broadening mechanism arises from the interaction between the photohole and the lattice. The strength of this interaction was observed to be strongly anisotropic and may have important implications for the momentum dependence of the first doped hole states.

  14. Phenomenological study of the normal state angle resolved photoelectron spectroscopy line shapes of high temperature superconducting cuprates

    NASA Astrophysics Data System (ADS)

    Matsuyama, Kazue; Dilip, Rohit; Gweon, G.-H.

    2015-03-01

    Understanding the normal state properties of high temperature (high-Tc) superconducting cuprates remains a central mystery in the high-Tc problem. Standing out among those mysterious properties are the anomalous angle resolved photoelectron spectroscopy (ARPES) line shapes. The extremely correlated Fermi liquid (ECFL) theory recently introduced by Shastry has renewed interest in quantitatively understanding ARPES line shapes. In this talk, we combine certain phenomenological considerations with the ECFL framework in order to describe the ARPES data. Our phenomenological models have the property of preserving the universal property of the original ECFL theory, while introducing phenomenological changes in a non-universal property. Our models describe, with unprecedented fidelity, the key aspects of the dichotomy between momentum distribution curves (MDCs) and energy distribution curves (EDCs) of high-Tc ARPES data. Therefore, our study goes well beyond the prevailing studies that discuss only MDCs and EDCs.

  15. High-temperature superconductivity in space-charge regions of lanthanum cuprate induced by two-dimensional doping

    NASA Astrophysics Data System (ADS)

    Baiutti, F.; Logvenov, G.; Gregori, G.; Cristiani, G.; Wang, Y.; Sigle, W.; van Aken, P. A.; Maier, J.

    2015-10-01

    The exploitation of interface effects turned out to be a powerful tool for generating exciting material properties. Such properties include magnetism, electronic and ionic transport and even superconductivity. Here, instead of using conventional homogeneous doping to enhance the hole concentration in lanthanum cuprate and achieve superconductivity, we replace single LaO planes with SrO dopant planes using atomic-layer-by-layer molecular beam epitaxy (two-dimensional doping). Electron spectroscopy and microscopy, conductivity measurements and zinc tomography reveal such negatively charged interfaces to induce layer-dependent superconductivity (Tc up to 35 K) in the space-charge zone at the side of the planes facing the substrate, where the strontium (Sr) profile is abrupt. Owing to the growth conditions, the other side exhibits instead a Sr redistribution resulting in superconductivity due to conventional doping. The present study represents a successful example of two-dimensional doping of superconducting oxide systems and demonstrates its power in this field.

  16. High T{sub c} in cuprates as a universal property of the electron–phonon system

    SciTech Connect

    Mazur, E. A.; Kagan, Yu.

    2015-08-15

    The Eliashberg theory, which is generalized due to peculiar properties of the finite-width electron band for electron–phonon (EP) systems with a variable electron density of states (DOS), as well as with allowance for the electron–hole nonequivalence of the frequency behavior of the chemical potential renormalization depending on the doping level and electron correlations in the vertex function, is used to study T{sub c} in cuprates. The phonon contribution to the nodal anomalous electron Green’s function (GF) is considered. Pairing within the total width of the electron band, and not only in a narrow layer at the Fermi surface, is taken into account. The calculated frequency and temperature dependences, as well as the dependence on the doping level of the complex renormalization ReZ, ImZ of the mass, complex renormalization Reχ(ω), Imχ(ω) of the chemical potential, and DOS N(ε) renormalized due to the EP interaction are used to calculate the electron nodal anomalous GF. It is found that the effect of suppressing the high-frequency contribution to the Eliashberg equations derived anew for the EP system with a finite width of the electron band is a decisive factor for the manifestation of the effect of high-temperature superconductivity (HTSC). It is shown that in the vicinity of the optimal hole-type doping level in cuprates, the high value of T{sub c} is reproduced by the spectral function of the electron–phonon interaction, which is obtained from tunneling experiments. Upon an increase in the doping level, leading to an increase in the degree of electron–hole nonequivalence, the new logarithmic term appearing in the equations for T{sub c} has a tendency to increase T{sub c}, while intensification of damping of charge carriers (especially suppression of the cutoff factor) leads to a decrease in T{sub c}.

  17. The Lifeworld Earth and a Modelled Earth

    ERIC Educational Resources Information Center

    Juuti, Kalle

    2014-01-01

    The goal of this paper is to study the question of whether a phenomenological view of the Earth could be empirically endorsed. The phenomenological way of thinking considers the Earth as a material entity, but not as an object as viewed in science. In the learning science tradition, tracking the process of the conceptual change of the shape of the…

  18. Earth on the Move.

    ERIC Educational Resources Information Center

    Naturescope, 1987

    1987-01-01

    Provides background information on the layers of the earth, the relationship between changes on the surface of the earth and its insides, and plate tectonics. Teaching activities are included, with some containing reproducible worksheets and handouts to accompany them. (TW)

  19. Earth's changeable atmosphere

    NASA Astrophysics Data System (ADS)

    2016-06-01

    Billions of years ago, high atmospheric greenhouse gas concentrations were vital to life's tenuous foothold on Earth. Despite new constraints, the composition and evolution of Earth's early atmosphere remains hazy.

  20. The Dynamic Earth.

    ERIC Educational Resources Information Center

    Siever, Raymond

    1983-01-01

    Discusses how the earth is a dynamic system that maintains itself in a steady state. Areas considered include large/small-scale earth motions, geologic time, rock and hydrologic cycles, and other aspects dealing with the changing face of the earth. (JN)

  1. Earth Science, K-12.

    ERIC Educational Resources Information Center

    Finson, Kevin D.; Enochs, Larry G.

    1987-01-01

    Argues that the teaching of earth science is largely neglected in the elementary science curriculum. Provides examples of how more instruction in the earth sciences at all levels can enhance decision-making skills. Discusses the relationship between various learning theories and certain instructional strategies in earth science. (TW)

  2. Interior of the Earth

    NASA Technical Reports Server (NTRS)

    Phillips, R. J.

    1984-01-01

    Basic questions regarding the interior of the Earth in the 1990's are discussed. Research problems in the areas of plate tectonics, the Earth mantle the Earth core, and continental structure are discussed. Observational requirements of the GRAVSAT satellite mission are discussed.

  3. Commensurate antiferromagnetic excitations as a signature of the pseudogap in the tetragonal high-Tc cuprate HgBa2CuO4+δ

    PubMed Central

    Chan, M. K.; Dorow, C. J.; Mangin-Thro, L.; Tang, Y.; Ge, Y.; Veit, M. J.; Yu, G.; Zhao, X.; Christianson, A. D.; Park, J. T.; Sidis, Y.; Steffens, P.; Abernathy, D. L.; Bourges, P.; Greven, M.

    2016-01-01

    Antiferromagnetic correlations have been argued to be the cause of the d-wave superconductivity and the pseudogap phenomena exhibited by the cuprates. Although the antiferromagnetic response in the pseudogap state has been reported for a number of compounds, there exists no information for structurally simple HgBa2CuO4+δ. Here we report neutron-scattering results for HgBa2CuO4+δ (superconducting transition temperature Tc≈71 K, pseudogap temperature T*≈305 K) that demonstrate the absence of the two most prominent features of the magnetic excitation spectrum of the cuprates: the X-shaped ‘hourglass' response and the resonance mode in the superconducting state. Instead, the response is Y-shaped, gapped and significantly enhanced below T*, and hence a prominent signature of the pseudogap state. PMID:26940332

  4. Commensurate antiferromagnetic excitations as a signature of the pseudogap in the tetragonal high-Tc cuprate HgBa2CuO4+δ

    DOE PAGESBeta

    Chan, M. K.; Dorow, C. J.; Mangin-Thro, L.; Tang, Y.; Ge, Y.; Veit, M. J.; Yu, G.; Zhao, X.; Christianson, A. D.; Park, J. T.; et al

    2016-03-04

    We report that antiferromagnetic correlations have been argued to be the cause of the d-wave superconductivity and the pseudogap phenomena exhibited by the cuprates. Although the antiferromagnetic response in the pseudogap state has been reported for a number of compounds, there exists no information for structurally simple HgBa2CuO4+δ. We report neutron-scattering results for HgBa2CuO4+δ (superconducting transition temperature Tc≈71 K, pseudogap temperature T*≈305 K) that demonstrate the absence of the two most prominent features of the magnetic excitation spectrum of the cuprates: the X-shaped ‘hourglass’ response and the resonance mode in the superconducting state. Instead, the response is Y-shaped, gapped andmore » significantly enhanced below T*, and hence a prominent signature of the pseudogap state.« less

  5. Electron-Doped Sr2IrO4 : An Analogue of Hole-Doped Cuprate Superconductors Demonstrated by Scanning Tunneling Microscopy

    NASA Astrophysics Data System (ADS)

    Yan, Y. J.; Ren, M. Q.; Xu, H. C.; Xie, B. P.; Tao, R.; Choi, H. Y.; Lee, N.; Choi, Y. J.; Zhang, T.; Feng, D. L.

    2015-10-01

    Sr2Ir O4 was predicted to be a high-temperature superconductor upon electron doping since it highly resembles the cuprates in crystal structure, electronic structure, and magnetic coupling constants. Here, we report a scanning tunneling microscopy/spectroscopy (STM/STS) study of Sr2Ir O4 with surface electron doping by depositing potassium (K) atoms. We find that as the electron doping increases, the system gradually evolves from an insulating state to a normal metallic state, via a pseudogaplike phase, and a phase with a sharp, V-shaped low-energy gap with about 95% loss of density of state (DOS) at EF . At certain K coverage (0.5-0.6 monolayer), the magnitude of the low-energy gap is 25-30 meV, and it closes at around 50 K. Our observations show that the electron-doped Sr2Ir O4 remarkably resembles hole-doped cuprate superconductors.

  6. Commensurate antiferromagnetic excitations as a signature of the pseudogap in the tetragonal high-Tc cuprate HgBa2CuO(4+δ).

    PubMed

    Chan, M K; Dorow, C J; Mangin-Thro, L; Tang, Y; Ge, Y; Veit, M J; Yu, G; Zhao, X; Christianson, A D; Park, J T; Sidis, Y; Steffens, P; Abernathy, D L; Bourges, P; Greven, M

    2016-01-01

    Antiferromagnetic correlations have been argued to be the cause of the d-wave superconductivity and the pseudogap phenomena exhibited by the cuprates. Although the antiferromagnetic response in the pseudogap state has been reported for a number of compounds, there exists no information for structurally simple HgBa2CuO(4+δ). Here we report neutron-scattering results for HgBa2CuO(4+δ) (superconducting transition temperature Tc≈71 K, pseudogap temperature T*≈305 K) that demonstrate the absence of the two most prominent features of the magnetic excitation spectrum of the cuprates: the X-shaped 'hourglass' response and the resonance mode in the superconducting state. Instead, the response is Y-shaped, gapped and significantly enhanced below T*, and hence a prominent signature of the pseudogap state. PMID:26940332

  7. Commensurate antiferromagnetic excitations as a signature of the pseudogap in the tetragonal high-Tc cuprate HgBa2CuO4+δ

    NASA Astrophysics Data System (ADS)

    Chan, M. K.; Dorow, C. J.; Mangin-Thro, L.; Tang, Y.; Ge, Y.; Veit, M. J.; Yu, G.; Zhao, X.; Christianson, A. D.; Park, J. T.; Sidis, Y.; Steffens, P.; Abernathy, D. L.; Bourges, P.; Greven, M.

    2016-03-01

    Antiferromagnetic correlations have been argued to be the cause of the d-wave superconductivity and the pseudogap phenomena exhibited by the cuprates. Although the antiferromagnetic response in the pseudogap state has been reported for a number of compounds, there exists no information for structurally simple HgBa2CuO4+δ. Here we report neutron-scattering results for HgBa2CuO4+δ (superconducting transition temperature Tc~71 K, pseudogap temperature T*~305 K) that demonstrate the absence of the two most prominent features of the magnetic excitation spectrum of the cuprates: the X-shaped `hourglass' response and the resonance mode in the superconducting state. Instead, the response is Y-shaped, gapped and significantly enhanced below T*, and hence a prominent signature of the pseudogap state.

  8. STM sub-gap structure in cuprates is a consequence of density waves, according to Mean-Field Theory and CDMFT

    NASA Astrophysics Data System (ADS)

    Verret, Simon; Roy, Jyotirmoy; Sénéchal, David; Tremblay, A.-M. S.

    Much work has been done to find how the pseudogap is related to charge density waves in cuprates. In scanning tunneling microscopy (STM) measurements, the superconducting gap and pseudogap of cuprates are sometimes accompanied by a small sub-gap structure at very low energy. This was documented early in vortex cores studies, and has now been reported at zero field for YBCO.(1) Here, we show that this can be caused by density waves, first through a standard mean-field approach, and then with Cellular Dynamical Mean-Field Theory for the Hubbard model using an exact diagonalization solver. We comment on the implication of these results for the relation between pseudogap and charge order. (1) Jens Bruér et al. arXiv:1507.06775 Supported by NSERC, CIFAR and the Tier I Canada Research Chair Program.

  9. Mission to Planet Earth

    NASA Technical Reports Server (NTRS)

    Tilford, Shelby G.; Asrar, Ghassem; Backlund, Peter W.

    1994-01-01

    Mission to Planet Earth (MTPE) is NASA's concept for an international science program to produce the understanding needed to predict changes in the Earth's environment. NASA and its interagency and international partners will place satellites carrying advanced sensors in strategic Earth orbits to gather multidisciplinary data. A sophisticated data system will process and archive an unprecedented amount of information about the Earth and how it works as a system. Increased understanding of the Earth system is a basic human responsibility, a prerequisite to informed management of the planet's resources and to the preservation of the global environment.

  10. Mission to Planet Earth

    NASA Technical Reports Server (NTRS)

    Wilson, Gregory S.; Backlund, Peter W.

    1992-01-01

    Mission to Planet Earth (MTPE) is NASA's concept for an international science program to produce the understanding needed to predict changes in the earth's environment. NASA and its interagency and international partners will place satellites carrying advanced sensors in strategic earth orbits to gather multidisciplinary data. A sophisticated data system will process and archive an unprecedented amount of information about the earth and how it works as a system. Increased understanding of the earth system is a basic human responsibility, a prerequisite to informed management of the planet's resources and to the preservation of the global environment.

  11. Earth - Pacific Ocean

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This color image of the Earth was obtained by the Galileo spacecraft early Dec. 12, 1990, when the spacecraft was about 1.6 million miles from the Earth. The color composite used images taken through the red, green and violet filters. The Pacific Ocean covers virtually all of the visible disk of the Earth in this picture. The glint of the Sun reflected from smooth water is near the center. This is a frame of the Galileo Earth spin movie, a 500-frame time-lapse motion picture showing a 25-hour period of Earths rotation and atmospheric dynamics.

  12. Crystal structure of the thermochromic bis­(di­ethyl­ammonium) tetra­chlorido­cuprate(II) complex

    PubMed Central

    Aldrich, Emily P.; Bussey, Katherine A.; Connell, Jennifer R.; Reinhart, Erin F.; Oshin, Kayode D.; Mercado, Brandon Q.; Oliver, Allen G.

    2016-01-01

    In the structure of the title complex salt, (Et2NH2)2[CuCl4], the asymmetric unit consists of four unique di­ethyl­ammonium cations and three unique tetra­chlorido­cuprate anions. Two of the three anions are located with their copper atoms on independent crystallographic twofold axes, while the remaining tetra­chlorido­cuprate is located at a general position of the ortho­rhom­bic space group P21212. Two of the three Cu atoms adopt a distorted square-planar/disphenoidal geometry and the third Cu atom has a regular square-planar coordination environment. The di­ethyl­ammonium cations form an extensive hydrogen-bonded network through N—H⋯Cl inter­actions with the tetra­chlorido­cuprate anions, resulting in a two-dimensional sheet-like hydrogen-bonded network parallel to the ab direction. The complex was observed to undergo a color shift from deep green at room temperature to pale yellow at temperatures above 328 K. PMID:26870581

  13. Extended van-Hove singularity in non-cuprate layered perovskite superconductor Sr{sub 2}RuO{sub 4}

    SciTech Connect

    Takahashi, T.; Yokoya, T.; Chainani, A.; Katayama-Yoshida, H.; Kasai, M.; Tokura, Y. |

    1996-12-31

    Low-temperature high-resolution angle-resolved photoemission spectroscopy (ARPES) have been performed on a non-cuprate superconductor Sr{sub 2}RuO{sub 4} ({Tc} {approximately} 1 K), which has the same crystal structure as La{sub 2}CuO{sub 4}, but with RuO{sub 2} layers replacing CuO{sub 2}. High-resolution ARPES spectra obtained along {Lambda}-Z line (Ru-O bonding direction) in Brillouin zone show the existence of an extended van-Hove singularity (VHS) close to E{sub F} (20 {+-} 2 meV) like high-{Tc} cuprates, regardless of the character of the electronic states at E{sub F}, suggesting that an extended VHS is a general feature of correlated two-dimensional d-electron metals. This requests re-examination of the VHS scenario for superconducting properties of cuprates, while the observed T-linear resistivity seems to be consistent with the present result.

  14. Thermodynamic properties of underdoped YBa2Cu3O6+x cuprates for doping values x ∈ (0 . 5 , 0 . 9)

    NASA Astrophysics Data System (ADS)

    Salas, P.; Solis, M. A.; Fortes, M.

    We extend the Boson-Fermion superconductivity model to include layered systems, such as underdoped cuprate superconductors YBa2Cu3O6+x, with x ∈ (0 . 5 , 0 . 9) ranging from underdoped to optimally doped. We model cuprates as a boson-fermion quantum gas mixture immersed in a layered structure, generated via a Dirac comb potential applied in one direction while the particles move freely in the other two directions. The optimum parameters of the system, which are the impenetrability of the planes and the paired fermion fraction, are obtained by minimizing the Helmholtz free energy and setting the experimental critical temperature Tc. Using this optimized scheme, we are able to predict the following thermodynamic properties of cuprates as a function of temperature: the entropy; the Helmholtz free energy; the electronic specific heat and the total specific heat for different doping values. Furthermore, we determinate the behavior of the jump height in the electronic specific heat, the normal electronic specific heat coefficient γ (Tc) , the quadratic α and cubic β terms of the specific heat for low temperatures, the ground state energy and the mass anisotropy as a function of doping. Comparison to experimental values reported is analyzed. We aknowledge the support from Grants UNAM-DGAPA-PAPIIT IN-111613 and CONACYT 221030, Mexico.

  15. People and the Earth

    NASA Astrophysics Data System (ADS)

    Rogers, John James William; Feiss, P. Geoffrey

    1998-03-01

    People and the Earth examines the numerous ways in which this planet enhances and limits our lifestyles. Written with wit and remarkable insight, and illustrated with numerous case histories, it provides a balanced view of the complex environmental issues facing our civilization. The authors look at the geologic restrictions on our ability to withdraw resources--food, water, energy, and minerals--from the earth, the effect human activity has on the earth, and the lingering damage caused by natural disasters. People and the Earth examines the basic components of our interaction with this planet, provides a lucid, scientific discussion of each issue, and speculates on what the future may hold. It provides the fundamental concepts that will enable us to make wise and conscientious choices on how to live our day-to-day lives. People and the Earth is an ideal introductory textbook and will also appeal to anyone concerned with our evolving relationship to the earth.

  16. Uderstanding Snowball Earth Deglaciation

    NASA Astrophysics Data System (ADS)

    Abbot, D. S.

    2012-12-01

    Earth, a normally clement planet comfortably in its star's habitable zone, suffered global or nearly global glaciation at least twice during the Neoproterozoic era (at about 635 and 710 million years ago). Viewed in the context of planetary evolution, these pan-global glaciations (Snowball Earth events) were extremely rapid, lasting only a few million years. The dramatic effect of the Snowball Earth events on the development of the planet can be seen through their link to rises in atmospheric oxygen and evolutionary innovations. These potential catastrophes on an otherwise clement planet can be used to gain insight into planetary habitability more generally. Since Earth is not currently a Snowball, a sound deglaciation mechanism is crucial for the viability of the Snowball Earth hypothesis. The traditional deglaciation mechanism is a massive build up of CO2 due to reduced weathering during Snowball Earth events until tropical surface temperatures reach the melting point. Once initiated, such a deglaciation might happen on a timescale of only dozens of thousands of years and would thrust Earth from the coldest climate in its history to the warmest. Therefore embedded in Snowball Earth events is an even more rapid and dramatic environmental change. Early global climate model simulations raised doubt about whether Snowball Earth deglaciation could be achieved at a CO2 concentration low enough to be consistent with geochemical data, which represented a potential challenge to the Snowball Earth hypothesis. Over the past few years dust and clouds have emerged as the essential missing additional processes that would allow Snowball Earth deglaciation at a low enough CO2 concentration. I will discuss the dust and cloud mechanisms and the modeling behind these ideas. This effort is critical for the broader implications of Snowball Earth events because understanding the specific deglaciation mechanism determines whether similar processes could happen on other planets.

  17. Ultrafast optical phenomena related to spin and orbital dynamics in the rare-earth cuprates R IICuO 4 (R = Pr, Nd, Sm)

    NASA Astrophysics Data System (ADS)

    Pavlov, Victor V.; Pisarev, Roman V.; Gridnev, Valery N.; Zhukov, Evgenie A.; Yakovlev, Dmitry R.; Bayer, Manfred

    2007-06-01

    Currently coherent spin phenomena are in the focus of wide research activity in such multidisciplinary fields as spintronics, quantum communication and information processing. 1-3 Among those, the optical orientation based on the transfer to media of the angular momentum carried by the circularly-polarized light plays very important role for disclosing basic processes that govern generation and relaxation of spin and orbital states. By using ultrafast pump-probe spectroscopy we show that optical pumping can induce spin-polarization in antiferromagnetic Mott insulators R IICuO 4 (R = Pr, Nd, Sm) providing a way for fast nonlinear manipulation of spin states on time scale of 100 fs and less. The driving mechanisms of the ultrafast spin orientation and dynamics in Mott insulators are the strong spin-orbit, spin-phonon and exchange interaction as inherent features of strongly-correlated systems both in the ground and excited states. High values of the corresponding nonlinear susceptibilities may have significant impact for novel ultrafast all-optical technologies.

  18. Earth - India and Australia

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This color image of the Earth was obtained by the Galileo spacecraft on Dec. 11, 1990, when the spacecraft was about 1.5 million miles from the Earth. The color composite used images taken through the red, green and violet filters. India is near the top of the picture, and Australia is to the right of center. The white, sunlit continent of Antarctica is below. Picturesque weather fronts are visible in the South Pacific, lower right. This is a frame of the Galileo Earth spin movie, a 500-frame time-lapse motion picture showing a 25-hour period of Earth's rotation and atmospheric dynamics.

  19. Capturing near-Earth asteroids around Earth

    NASA Astrophysics Data System (ADS)

    Hasnain, Zaki; Lamb, Christopher A.; Ross, Shane D.

    2012-12-01

    The list of detected near-Earth asteroids (NEAs) is constantly growing. NEAs are likely targets for resources to support space industrialization, as they may be the least expensive source of certain needed raw materials. The limited supply of precious metals and semiconducting elements on Earth may be supplemented or even replaced by the reserves floating in the form of asteroids around the solar system. Precious metals make up a significant fraction NEAs by mass, and even one metallic asteroid of ˜1km size and fair enrichment in platinum-group metals would contain twice the tonnage of such metals already harvested on Earth. There are ˜1000 NEAs with a diameter of greater than 1 km. Capturing these asteroids around the Earth would expand the mining industry into an entirely new dimension. Having such resources within easy reach in Earth's orbit could provide an off-world environmentally friendly remedy for impending terrestrial shortages, especially given the need for raw materials in developing nations. In this paper, we develop and implement a conceptually simple algorithm to determine trajectory characteristics necessary to move NEAs into capture orbits around the Earth. Altered trajectories of asteroids are calculated using an ephemeris model. Only asteroids of eccentricity less than 0.1 have been studied and the model is restricted to the ecliptic plane for simplicity. We constrain the time of retrieval to be 10 years or less, based on considerations of the time to return on investment. For the heliocentric phase, constant acceleration is assumed. The acceleration required for transporting these asteroids from their undisturbed orbits to the sphere of influence of the Earth is the primary output, along with the impulse or acceleration necessary to effect capture to a bound orbit once the Earth's sphere of influence is reached. The initial guess for the constant acceleration is provided by a new estimation method, similar in spirit to Edelbaum's. Based on the

  20. Three energy scales in the superconducting state of hole-doped cuprates detected by electronic Raman scattering

    SciTech Connect

    Benhabib, S.; Gu, G. D.; Gallais, Y.; Cazayous, M.; Measson, M. -A.; Zhong, R. D.; Schneeloch, J.; Forget, A.; Colson, D.; Sacuto, A.

    2015-10-06

    We explore by electronic Raman scattering the superconducting state of the Bi2Sr2CaCu2O8+δ (Bi-2212) crystal by performing a fine-tuned doping study. We find three distinct energy scales in A1g, B1g, and B2g symmetries which show three distinct doping dependencies. Above p=0.22, the three energies merge; below p=0.12, the A1g scale is no longer detectable, while the B1g and B2g scales become constant in energy. In between, the A1g and B1g scales increase monotonically with underdoping, while the B2g one exhibits a maximum at p=0.16. The three superconducting energy scales appear to be a universal feature of hole-doped cuprates. Furthermore, we propose that the nontrivial doping dependencies of the three scales originate from the Fermi-surface changes and reveal competing orders inside the superconducting dome.

  1. Low energy impurity kink in the normal and anomalous self-energies in Bi-cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Bok, Jin Mo; Bae, Jong Ju; Hong, Seung Hwan; Zhou, X. J.; Choi, Han-Yong

    2015-08-01

    The sharp low energy kink (LEK) in quasiparticle (qp) spectra well below the superconducting energy gap observed in the angle-resolved photo-emission spectroscopy (ARPES) of the Bi-cuprates may be understood in terms of the forward scattering impurities located off the Cu-O planes. The relevance of the idea has been established by comparing the calculated normal self-energy from the off-plane impurity effects and the extracted one from the self-energy analysis of Bi2Sr2CaCu2O8+δ (Bi2212) ARPES data in Hong et al. [Phys. Rev. Lett. 113, 057001 (2014)]. In addition to the explanation of the LEK, this is a necessary step to analyze ARPES data, to reveal the spectrum of fluctuations promoting superconductivity. We also present the extracted anomalous self-energy from the self-energy analysis, which is its first experimental determination as far as we are aware of. The extracted anomalous self-energy and its implications are discussed in comparison with the calculated impurity self-energy term.

  2. Emergence of charge order in a staggered loop-current phase of cuprate high-temperature superconductors

    NASA Astrophysics Data System (ADS)

    Atkinson, W. A.; Kampf, A. P.; Bulut, S.

    2016-04-01

    We study the emergence of charge-ordered phases within a π -loop-current (π LC ) model for the pseudogap based on a three-band model for underdoped cuprate superconductors. Loop currents and charge ordering are driven by distinct components of the short-range Coulomb interactions: loop currents result from the repulsion between nearest-neighbor copper and oxygen orbitals, while charge order results from repulsion between neighboring oxygen orbitals. We find that the leading π LC phase has an antiferromagnetic pattern similar to previously discovered staggered flux phases, and that it emerges abruptly at hole dopings p below the Van Hove filling. Subsequent charge-ordering tendencies in the π LC phase reveal that diagonal d -charge density waves (dCDWs) are suppressed by the loop currents while axial order competes more weakly. In some cases we find a wide temperature range below the loop-current transition, over which the susceptibility towards an axial dCDW is large. In these cases, short-range axial charge order may be induced by doping-related disorder. A unique feature of the coexisting dCDW and π LC phases is the emergence of an incommensurate modulation of the loop currents. If the dCDW is biaxial (checkerboard) then the resulting incommensurate current pattern breaks all mirror and time-reversal symmetries, thereby allowing for a polar Kerr effect.

  3. Onsager rule, quantum oscillation frequencies, and the density of states in the mixed-vortex state of cuprates

    NASA Astrophysics Data System (ADS)

    Wang, Zhiqiang; Chakravarty, Sudip

    2016-05-01

    The Onsager rule determines the relationship between Fermi surface area and frequencies of quantum oscillations in magnetic fields. We show that this rule remains intact to an excellent approximation in the mixed-vortex state of the underdoped cuprates even though the Landau level index n may be fairly low, n ˜10 . The models we consider are fairly general, consisting of a variety of density wave states combined with d -wave superconductivity within a mean field theory. Vortices are introduced as quenched disorder and averaged over many realizations, which can be considered as snapshots of a vortex liquid state. We also show that the oscillations ride on top of a field independent density of states ρ (B ) for higher fields. This feature appears to be consistent with recent specific heat measurements [C. Marcenat et al., Nature Communications 6, 7927 (2015), 10.1038/ncomms8927]. The experimental data do not go to low fields at the lowest temperature 3 K. Thus, we cannot compare the density of state for the entire field range. Of course, the high temperature data are linear in the field at lower fields, as they should be, but our theory is only valid at very low temperatures, ideally at zero temperature. At lower fields and zero temperature we model the system as an ordered vortex lattice, and show that its density of states follows a dependence ρ (B ) ∝√{B } in agreement with the semiclassical results [JETP Lett 58, 469 (1993)].

  4. Muon Spin Relaxation Studies of Zn-Substitution Effects in High-{ital T{sub {ital c}}} Cuprate Superconductors

    SciTech Connect

    Nachumi, B.; Keren, A.; Kojima, K.; Larkin, M.; Luke, G.M.; Merrin, J.; Tchernyshoev, O.; Uemura, Y.J.; Ichikawa, N.; Goto, M.; Uchida, S.

    1996-12-01

    We have performed transverse-field muon spin relaxation measurements of the Zn-substituted cuprate high-{ital T}{sub {ital c}} superconductors: La{sub 2{minus}{ital x}}Sr{sub {ital x}}(Cu{sub 1{minus}{ital y}}Zn{sub {ital y}})O{sub 4} and YBa{sub 2}(Cu{sub 1{minus}{ital y}}Zn{sub {ital y}}){sub 3}O{sub 6.63}. The superconducting carrier density/effective mass {ital n}{sub {ital s}}/{ital m}{sup *} ratio at {ital T}{r_arrow}0 decreases with increasing Zn concentration, in a manner consistent with our {open_quote}{open_quote}swiss cheese{close_quote}{close_quote} model in which charge carriers within an area {pi}{xi}{sub {ital ab}}{sup 2} around each Zn are excluded from the superfluid. We discuss this result in the context of Bose condensation, pair localization, and pair breaking. {copyright} {ital 1996 The American Physical Society.}

  5. Three energy scales in the superconducting state of hole-doped cuprates detected by electronic Raman scattering

    DOE PAGESBeta

    Benhabib, S.; Gu, G. D.; Gallais, Y.; Cazayous, M.; Measson, M. -A.; Zhong, R. D.; Schneeloch, J.; Forget, A.; Colson, D.; Sacuto, A.

    2015-10-06

    We explore by electronic Raman scattering the superconducting state of the Bi2Sr2CaCu2O8+δ (Bi-2212) crystal by performing a fine-tuned doping study. We find three distinct energy scales in A1g, B1g, and B2g symmetries which show three distinct doping dependencies. Above p=0.22, the three energies merge; below p=0.12, the A1g scale is no longer detectable, while the B1g and B2g scales become constant in energy. In between, the A1g and B1g scales increase monotonically with underdoping, while the B2g one exhibits a maximum at p=0.16. The three superconducting energy scales appear to be a universal feature of hole-doped cuprates. Furthermore, we proposemore » that the nontrivial doping dependencies of the three scales originate from the Fermi-surface changes and reveal competing orders inside the superconducting dome.« less

  6. High-temperature superconductivity in space-charge regions of lanthanum cuprate induced by two-dimensional doping

    PubMed Central

    Baiutti, F.; Logvenov, G.; Gregori, G.; Cristiani, G.; Wang, Y.; Sigle, W.; van Aken, P. A.; Maier, J.

    2015-01-01

    The exploitation of interface effects turned out to be a powerful tool for generating exciting material properties. Such properties include magnetism, electronic and ionic transport and even superconductivity. Here, instead of using conventional homogeneous doping to enhance the hole concentration in lanthanum cuprate and achieve superconductivity, we replace single LaO planes with SrO dopant planes using atomic-layer-by-layer molecular beam epitaxy (two-dimensional doping). Electron spectroscopy and microscopy, conductivity measurements and zinc tomography reveal such negatively charged interfaces to induce layer-dependent superconductivity (Tc up to 35 K) in the space-charge zone at the side of the planes facing the substrate, where the strontium (Sr) profile is abrupt. Owing to the growth conditions, the other side exhibits instead a Sr redistribution resulting in superconductivity due to conventional doping. The present study represents a successful example of two-dimensional doping of superconducting oxide systems and demonstrates its power in this field. PMID:26481902

  7. A novel ferrimagnetic irido-cuprate: IrSr{sub 2}GdCu{sub 2}O{sub 8}

    SciTech Connect

    Dos Santos-Garcia, A.J.; Aguirre, Myriam H.; Moran, E.; Saez Puche, R. . E-mail: rsp92@quim.ucm.es; Alario-Franco, M.A. . E-mail: maaf@quim.ucm.es

    2006-05-15

    We have performed an investigation of the structural, microstructural and magnetic properties of the new compound IrSr{sub 2}GdCu{sub 2}O{sub 8}. The sample was prepared under high temperature ({approx}1393K) and high-pressure conditions ({approx}60Kbars) in a Belt type apparatus. X-ray diffraction (XRD) analysis shows that this irido-cuprate is isostructural with the corresponding Ru-1212 phase. Structurally, this material shows an interesting hierarchy of ordering phenomena, whose observation actually depends on the technique used to analyze the material: from a 'simple' cell a{sub p}xa{sub p}x3a{sub p} which is supported by XRD, through a 'diagonal' one, {approx}2a{sub p}x2a{sub p}x3a{sub p} as seen by SAED, to a microdomain texture of this last one cell supported by HREM. A ferrimagnetic Ir{sup IV}-Gd{sup III} spin ordering is observed below 15K. The iridium oxidation state seems to be +4.

  8. Anomalous charge and negative-charge-transfer insulating state in cuprate chain compound KCuO2

    NASA Astrophysics Data System (ADS)

    Choudhury, D.; Rivero, P.; Meyers, D.; Liu, X.; Cao, Y.; Middey, S.; Whitaker, M. J.; Barraza-Lopez, S.; Freeland, J. W.; Greenblatt, M.; Chakhalian, J.

    2015-11-01

    Using a combination of x-ray absorption spectroscopy (XAS) experiments and first-principles calculations, we demonstrate that insulating KCuO2 contains Cu in an unusually high formal 3+ valence state, and the ligand-to-metal (O-to-Cu) charge-transfer energy is intriguingly negative (Δ ˜-1.5 eV) and has a dominant (˜60 % ) ligand-hole character in the ground state akin to the high Tc cuprate Zhang-Rice state. Unlike most other formal Cu3 + compounds, the Cu 2 p XAS spectra of KCuO2 exhibit pronounced 3 d8 (Cu3 +) multiplet structures, which account for ˜40 % of its ground state wave function. Ab initio calculations elucidate the origin of the band gap in KCuO2 as arising primarily from strong intracluster Cu 3 d -O 2 p hybridizations (tpd); the value of the band gap decreases with a reduced value of tpd. Further, unlike conventional negative-charge-transfer insulators, the band gap in KCuO2 persists even for vanishing values of Coulomb repulsion U , underscoring the importance of single-particle band-structure effects connected to the one-dimensional nature of the compound.

  9. Core-level Photoemission Study for Cuprates with a Dynamical Mean-Field Approach Considering Realistic Crystal Structure

    NASA Astrophysics Data System (ADS)

    Hariki, Atsushi; Uozumi, Takayuki

    2013-03-01

    Recently, remarkable experimental progress reveals some characteristic spectral features in the 2p3/2main line of Cu 2p core-level X-ray photoemission spectra (XPS). The structures show strong material dependence and drastic changes for electron or hole doping. Van Veenendaal et al., pointed out that the main line shape is strongly affected by the so-called nonlocal screening which is accompanied by a formation of a Zhang-Rice singlet (ZRS) in the XPS final state. On the other hand, Taguchi et al., shows these features are reproduced by introducing an phenomenological extended impurity model. We consider that this topic on 2pXPS of cuprates still remain controversial. In this study, we propose another approach based on the dynamical mean field theory(DMFT) considering the realistic crystal structure. Many-particle effects including the ZRS is appropriately embedded in the hybridization function of a single impurity Anderson model through the DMFT self-consistent cycle. Our approach reproduces experimental results and shows that the Cu 2p3/2 main line is closely related with the quasi-particle structure near the Fermi energy.

  10. Core-Level Photoemission Study for Undoped Cuprates with a Dynamical Mean-Field Approach Considering Realistic Crystal Structure

    NASA Astrophysics Data System (ADS)

    Hariki, Atsushi; Ichinozuka, Yoshiyuki; Uozumi, Takayuki

    2013-02-01

    The 2p3/2 main-line shape of Cu 2p X-ray photoemission spectra for undoped cuprates is studied by means of a dp model within a dynamical mean-field approximation. In order to consider the realistic CuO2 planar structure, we developed a framework combining an impurity Anderson model with a tight-binding calculation for the CuO2 plane. A characteristic partial density of states is obtained for a diagonally ordered antiferromagnetic phase. The calculated 2p3/2 main line shows a broad-band feature formed by screened final states with a hole in the O 2p band and by those accompanied by Zhang--Rice singlet formation. The strong relevance is emphasized between spectral shape and hybridization function which is self-consistently determined within the present framework. Qualitative agreement is also found with hard X-ray photoemission spectra observed for La2CuO4 and Nd2CuO4.

  11. The deviation in the d-wave behaviour of the gaps in Cuprate high-temperature superconductors

    NASA Astrophysics Data System (ADS)

    Hüfner, S.; Müller, F.

    2012-12-01

    The (Cuprate) High Temperature Superconductors (CHTSCs) are characterised by a d-wave gap of the cos(2ϕ) form. In some systems, deviations from this canonical behaviour are observed in ARPES experiments. In this note ARPES experiments on the gaps of the one layer systems Bi2201 and LSCO are inspected and analysed. The available data give for optimal doping a superconducting gap of (9 ± 2) meV, and a pseudogap, which originates from the preformed pairs, of (15 ± 3) meV. A second pseudogap, (35 ± 5) meV, with a shorter wave vector is observed in many experiments and is ascribed to an additional ordered structure. The existence of the two pseudogaps is responsible for the deviation from the canonical cos(2ϕ) behaviour. Thus the question whether the pseudogap observed in the CHTSC by ARPES is due to preformed pairs or due to additional order does not really exist at least in the one layer compounds. There are two pseudogaps present in the one layer CHTSC, one due to preformed pairs, which become superconducting below Tc, and a second one, reflecting an additional order, which is most likely the checkerboard structure.

  12. Cool Earth Solar

    ScienceCinema

    Lamkin, Rob; McIlroy, Andy; Swalwell, Eric; Rajan, Kish

    2014-02-26

    In a public-private partnership that takes full advantage of the Livermore Valley Open Campus (LVOC) for the first time, Sandia National Laboratories and Cool Earth Solar have signed an agreement that could make solar energy more affordable and accessible. In this piece, representatives from Sandia, Cool Earth Solar, and leaders in California government all discuss the unique partnership and its expected impact.

  13. Hands On Earth Science.

    ERIC Educational Resources Information Center

    Weisgarber, Sherry L.; Van Doren, Lisa; Hackathorn, Merrianne; Hannibal, Joseph T.; Hansgen, Richard

    This publication is a collection of 13 hands-on activities that focus on earth science-related activities and involve students in learning about growing crystals, tectonics, fossils, rock and minerals, modeling Ohio geology, geologic time, determining true north, and constructing scale-models of the Earth-moon system. Each activity contains…

  14. The Earth's Core.

    ERIC Educational Resources Information Center

    Jeanloz, Raymond

    1983-01-01

    The nature of the earth's core is described. Indirect evidence (such as that determined from seismological data) indicates that it is an iron alloy, solid toward its center but otherwise liquid. Evidence also suggests that it is the turbulent flow of the liquid that generates the earth's magnetic field. (JN)

  15. The Earth Needs You!

    ERIC Educational Resources Information Center

    Curriculum Review, 2008

    2008-01-01

    Celebrated annually on April 22, schools and communities organize numerous activities during Earth Day to promote awareness. To help teachers plan their own initiatives and to learn more about what is happening around the world, they can join the Earth Day Network at: http://network.earthday.net/. Once they have joined, they can create a webpage…

  16. The Earth Charter

    ERIC Educational Resources Information Center

    Journal of Education for Sustainable Development, 2010

    2010-01-01

    Humanity is part of a vast evolving universe. Earth is alive with a unique community of life. The forces of nature make existence a demanding and uncertain adventure, but Earth has provided the conditions essential to life's evolution. The resilience of the community of life and the well-being of humanity depend upon preserving a healthy biosphere…

  17. Earth System Science Project

    ERIC Educational Resources Information Center

    Rutherford, Sandra; Coffman, Margaret

    2004-01-01

    For several decades, science teachers have used bottles for classroom projects designed to teach students about biology. Bottle projects do not have to just focus on biology, however. These projects can also be used to engage students in Earth science topics. This article describes the Earth System Science Project, which was adapted and developed…

  18. Earth-Bonding.

    ERIC Educational Resources Information Center

    Norgaard, Jim

    1988-01-01

    Defines "earth bonding" as dynamic interaction between individual and physical environment. Examines methods and goals of traditional environmental education. Describes development of five-day camping workshop for 11 outdoor education teachers. Describes how workshop facilitated earth bonding for teachers. Calls for further research in "bonding…

  19. Introducing Earth's Orbital Eccentricity

    ERIC Educational Resources Information Center

    Oostra, Benjamin

    2015-01-01

    Most students know that planetary orbits, including Earth's, are elliptical; that is Kepler's first law, and it is found in many science textbooks. But quite a few are mistaken about the details, thinking that the orbit is very eccentric, or that this effect is somehow responsible for the seasons. In fact, the Earth's orbital eccentricity is…

  20. Skylab Explores the Earth.

    ERIC Educational Resources Information Center

    National Aeronautics and Space Administration, Washington, DC.

    This book describes the Skylab 4 Earth Explorations Project. Photographs of the earth taken by the Skylab astronauts are reproduced here and accompanied by an analytical and explanatory text. Some of the geological and geographical topics covered are: (1) global tectonics - some geological analyses of observations and photographs from Skylab; (2)…

  1. Earth and ocean modeling

    NASA Technical Reports Server (NTRS)

    Knezovich, F. M.

    1976-01-01

    A modular structured system of computer programs is presented utilizing earth and ocean dynamical data keyed to finitely defined parameters. The model is an assemblage of mathematical algorithms with an inherent capability of maturation with progressive improvements in observational data frequencies, accuracies and scopes. The Eom in its present state is a first-order approach to a geophysical model of the earth's dynamics.

  2. Spaceship Earth Curriculum Project.

    ERIC Educational Resources Information Center

    McInnis, Noel; And Others

    Three separate papers from the Project are included in this document. One of these, by the Center staff, is entitled "Potentials of the Spaceship Earth Metaphor". It discusses static, dynamic, and analogic representations of spaceship earth and their educational value. A second paper, "Some Resources for Introducing Environmental Education Into…

  3. Mission to Planet Earth

    NASA Technical Reports Server (NTRS)

    Wilson, Gregory S.; Backlund, Peter W.

    1992-01-01

    Mission to Planet Earth (MTPE) is NASA's concept for an international science program to produce the understanding needed to predict changes in the Earth's environment. NASA and its interagency and international partners will place satellites carrying advanced sensors in strategic Earth orbits to gather multidisciplinary data. A sophisticated data system will process and archive an unprecedented amount of information about the Earth and how it works as a system. Increased understanding of the Earth system is a basic human responsibility, a prerequisite to informed management of the planet's resources and to the preservation of the global environment. An overview of the MTPE, flight programs, data and information systems, interdisciplinary research efforts, and international coordination, is presented.

  4. Earth Science Week evolves

    NASA Astrophysics Data System (ADS)

    Earth Science Week, October 7-13, is an annual grassroots effort sponsored by the American Geological Institute (AGI) and its member societies, of which AGU is the largest. This year, for the first time, Earth Science Week has a general theme, evolution in Earth history. The Earth Science Week information kit for 2001, available from AGI, includes a variety of posters, bookmarks, and other materials that illustrate this concept. The kit contains a new 32-page “Ideas and Activities” booklet that emphasizes evolution in Earth history through an array of activities about rocks, fossils, and geologic time. It also has information on the upcoming Public Broadcasting Service series, “Evolution,” which is to be aired in late September.

  5. Earth Science Informatics - Overview

    NASA Technical Reports Server (NTRS)

    Ramapriyan, H. K.

    2015-01-01

    Over the last 10-15 years, significant advances have been made in information management, there are an increasing number of individuals entering the field of information management as it applies to Geoscience and Remote Sensing data, and the field of informatics has come to its own. Informatics is the science and technology of applying computers and computational methods to the systematic analysis, management, interchange, and representation of science data, information, and knowledge. Informatics also includes the use of computers and computational methods to support decision making and applications. Earth Science Informatics (ESI, a.k.a. geoinformatics) is the application of informatics in the Earth science domain. ESI is a rapidly developing discipline integrating computer science, information science, and Earth science. Major national and international research and infrastructure projects in ESI have been carried out or are on-going. Notable among these are: the Global Earth Observation System of Systems (GEOSS), the European Commissions INSPIRE, the U.S. NSDI and Geospatial One-Stop, the NASA EOSDIS, and the NSF DataONE, EarthCube and Cyberinfrastructure for Geoinformatics. More than 18 departments and agencies in the U.S. federal government have been active in Earth science informatics. All major space agencies in the world, have been involved in ESI research and application activities. In the United States, the Federation of Earth Science Information Partners (ESIP), whose membership includes nearly 150 organizations (government, academic and commercial) dedicated to managing, delivering and applying Earth science data, has been working on many ESI topics since 1998. The Committee on Earth Observation Satellites (CEOS)s Working Group on Information Systems and Services (WGISS) has been actively coordinating the ESI activities among the space agencies. Remote Sensing; Earth Science Informatics, Data Systems; Data Services; Metadata

  6. Earth as art three

    USGS Publications Warehouse

    U.S. Geological Survey

    2010-01-01

    For most of us, deserts, mountains, river valleys, coastlines even dry lakebeds are relatively familiar features of the Earth's terrestrial environment. For earth scientists, they are the focus of considerable scientific research. Viewed from a unique and unconventional perspective, Earth's geographic attributes can also be a surprising source of awe-inspiring art. That unique perspective is space. The artists for the Earth as Art Three exhibit are the Landsat 5 and Landsat 7 satellites, which orbit approximately 705 kilometers (438 miles) above the Earth's surface. While studying the images these satellites beam down daily, researchers are often struck by the sheer beauty of the scenes. Such images inspire the imagination and go beyond scientific value to remind us how stunning, intricate, and simply amazing our planet's features can be. Instead of paint, the medium for these works of art is light. But Landsat satellite sensors don't see light as human eyes do; instead, they see radiant energy reflected from Earth's surface in certain wavelengths, or bands, of red, green, blue, and infrared light. When these different bands are combined into a single image, remarkable patterns, colors, and shapes emerge. The Earth as Art Three exhibit provides fresh and inspiring glimpses of different parts of our planet's complex surface. The images in this collection were chosen solely based on their aesthetic appeal. Many of the images have been manipulated to enhance color variations or details. They are not intended for scientific interpretation only for your viewing pleasure. Enjoy!

  7. NASA's Earth observation programs

    NASA Astrophysics Data System (ADS)

    Neeck, Steven P.; Hammer, Theodore F.

    2006-09-01

    The purpose of NASA's Science Mission Directorate's Earth Science Division (ESD) is to develop a scientific understanding of Earth's system and its response to natural or human-induced changes, and to improve prediction of climate, weather, and natural hazards. ESD conducts and sponsors research, collects new observations from space, develops technologies and extends science and technology education to learners of all ages. We work closely with our global partners in government, industry, and the public to enhance economic security, and environmental stewardship, benefiting society in many tangible ways. We conduct and sponsor research to answer fundamental science questions about the changes we see in climate, weather, and natural hazards, and deliver sound science that helps decision-makers make informed decisions. Using the view from space to study the Earth, researchers can better predict critical changes to Earth and its space environment. ESD has a critical role in implementing three major national directives: •Climate Change Research through the Climate Change Science Program •Global Earth Observation System of Systems through the Interagency Working Group on Earth Observations (IWGEO) •U.S Ocean Action Plan. NASA's ESD currently has a system of spacecraft collecting observations of the Earth system and in the months and years ahead will deploy new satellites and constellations with advanced measurement capabilities.

  8. Magnetization behavior of RE123 bulk magnets bearing twin seed-crystals in pulsed field magnetization processes

    NASA Astrophysics Data System (ADS)

    Oka, T.; Miyazaki, T.; Ogawa, J.; Fukui, S.; Sato, T.; Yokoyama, K.; Langer, M.

    2016-02-01

    Melt-textured Y-Ba-Cu-O high temperature superconducting bulk magnets were fabricated by the cold seeding method with using single or twin-seed crystals composed of Nd-Ba-Cu-O thin films on MgO substrates. The behavior of the magnetic flux penetration into anisotropic-grown bulk magnets thus fabricated was precisely evaluated during and after the pulsed field magnetization operated at 35 K. These seed crystals were put on the top surfaces of the precursors to grow large grains during the melt-processes. Although we know the magnetic flux motion is restricted by the enhanced pinning effect in temperature ranges lower than 77 K, we observed that flux invasion occurred at applied fields of 3.3 T when the twin seeds were used. This is definitely lower than those of 3.7 T when the single-seeds were employed. This means that the magnetic fluxes are capable of invading into twin-seeded bulk magnets more easily than single-seeded ones. The twin seeds form the different grain growth regions, the narrow-GSR (growth sector region) and wide-GSR, according to the different grain growth directions which are parallel and normal to the rows of seed crystals, respectively. The invading flux measurements revealed that the magnetic flux invades the sample from the wide-GSR prior to the narrow-GSR. It suggests that such anisotropic grain growth leads to different distributions of pinning centers, variations of J c values, and the formation of preferential paths for the invading magnetic fluxes. Using lower applied fields definitely contributed to lowering the heat generation during the PFM process, which, in turn, led to enhanced trapped magnetic fluxes.

  9. Doping Dependence of the $(\\pi,\\pi)$ Shadow Band in La-Based Cuprates Studied by Angle-Resolved Photoemission Spectroscopy

    SciTech Connect

    Shen, Z. X.

    2011-08-15

    The ({pi},{pi}) shadow band (SB) in La-based cuprate family (La214) was studied by angle-resolved photoemission spectroscopy (ARPES) over a wide doping range from x = 0.01 to x = 0.25. Unlike the well-studied case of the Bi-based cuprate family, an overall strong, monotonic doping dependence of the SB intensity at the Fermi level (E{sub F}) was observed. In contrast to a previous report for the presence of the SB only close to x = 1/8, we found it exists in a wide doping range, associated with a doping-independent ({pi},{pi}) wave vector but strongly doping-dependent intensity: It is the strongest at x {approx} 0.03 and systematically diminishes as the doping increases until it becomes negligible in the overdoped regime. This SB with the observed doping dependence of intensity can in principle be caused by the antiferromagnetic fluctuations or a particular form of low-temperature orthorhombic lattice distortion known to persist up to x {approx} 0.21 in the system, with both being weakened with increasing doping. However, a detailed binding energy dependent analysis of the SB at x = 0.07 does not appear to support the former interpretation, leaving the latter as a more plausible candidate, despite a challenge in quantitatively linking the doping dependences of the SB intensity and the magnitude of the lattice distortion. Our finding highlights the necessity of a careful and global consideration of the inherent structural complications for correctly understanding the cuprate Fermiology and its microscopic implication.

  10. Earths, Super-Earths, and Jupiters

    NASA Astrophysics Data System (ADS)

    Chiang, Eugene; Lee, Eve J.

    2015-12-01

    We review and add to the theory of how planets acquire atmospheres from parent circumstellar disks. We derive (in real time) a simple and general analytic expression for how a planet's atmosphere grows with time, as a function of the underlying core mass and nebular conditions, including the gas metallicity. Planets accrete as much gas as can cool: an atmosphere's doubling time is given by its Kelvin-Helmholtz time. The theory can be applied in any number of settings --- gas-rich vs. gas-poor nebulae; dusty vs. dust-free atmospheres; close-in vs. far-out distances --- and is confirmed against detailed numerical models for objects ranging in mass from Mars (0.1 Mearth) to the most extreme super Earths (10--20 Mearth). We explain why heating from planetesimal accretion, commonly invoked in models of core accretion, is irrelevant. This talk sets the stage for another presentation, "Breeding Super-Earths and Birthing Super-Puffs".

  11. Earth from Above

    NASA Astrophysics Data System (ADS)

    Parkinson, Claire L.

    Earth from Above provides an easy introduction to understanding and interpreting satellite images, using illustrative examples to instruct on the fantastically informative new global data sets. Beginning with two short chapters on visible satellite images and radiation, the book then covers six key Earth-atmosphere variables on such environmentally important topics as the Antarctic ozone hole, El Nino, deforestation, the missing carbon dilemma, and the effects of sea ice, snow cover, and volcanoes on atmospheric temperatures. A final chapter broadens the discussion to consider satellite Earth observations in general.

  12. Rare earth gas laser

    DOEpatents

    Krupke, W.F.

    1975-10-31

    A high energy gas laser with light output in the infrared or visible region of the spectrum is described. Laser action is obtained by generating vapors of rare earth halides, particularly neodymium iodide or, to a lesser extent, neodymium bromide, and disposing the rare earth vapor medium in a resonant cavity at elevated temperatures; e.g., approximately 1200/sup 0/ to 1400/sup 0/K. A particularly preferred gaseous medium is one involving a complex of aluminum chloride and neodymium chloride, which exhibits tremendously enhanced vapor pressure compared to the rare earth halides per se, and provides comparable increases in stored energy densities.

  13. Introducing Earth's Orbital Eccentricity

    NASA Astrophysics Data System (ADS)

    Oostra, Benjamin

    2015-12-01

    Most students know that planetary orbits, including Earth's, are elliptical; that is Kepler's first law, and it is found in many science textbooks. But quite a few are mistaken about the details, thinking that the orbit is very eccentric, or that this effect is somehow responsible for the seasons. In fact, the Earth's orbital eccentricity is small, and its only effect on the seasons is their unequal durations. Here I show a pleasant way to guide students to the actual value of Earth's orbital eccentricity, starting from the durations of the four seasons. The date of perihelion is also found.

  14. Cu-O network-dependent core-hole screening in low-dimensional cuprate systems: A high-resolution x-ray photoemission study

    SciTech Connect

    Boeske, T.; Maiti, K.; Knauff, O.; Ruck, K.; Golden, M.S.; Krabbes, G.; Fink, J.; Osafune, T.; Motoyama, N.; Eisaki, H.; Uchida, S.

    1998-01-01

    We present an experimental study of the dynamics of holes in the valence bands of zero-, one-, and two-dimensional undoped model cuprates, as expressed via the screening of a Cu 2p core hole. The response depends strongly upon the dimensionality and the details of the Cu-O-Cu network geometry and clearly goes beyond the present theoretical state-of-the-art description within the three-band d-p model. {copyright} {ital 1998} {ital The American Physical Society}

  15. Crystal structure of bis­(N,N,N′,N′-tetra­methyl­guanidinium) tetra­chlorido­cuprate(II)

    PubMed Central

    Ndiaye, Mamadou; Samb, Abdoulaye; Diop, Libasse; Maris, Thierry

    2016-01-01

    In the structure of the title salt, (C5H14N3)2[CuCl4], the CuII atom in the anion lies on a twofold rotation axis. The tetra­chlorido­cuprate(II) anion adopts a flattened tetra­hedral coordination environment and inter­acts electrostatically with the tetra­methyl­guanidinium cation. The crystal packing is additionally consolidated through N—H⋯Cl and C—H⋯Cl hydrogen bonds, resulting in a three-dimensional network structure. PMID:27555960

  16. A Study of Topological Insulator States of Half-Heusler Materials and the Momentum Density of Overdoped Cuprates

    NASA Astrophysics Data System (ADS)

    Al-Sawai, Wael M.

    We have applied first-principles calculations to investigate the topological insulator state of half-Heusler materials and the momentum density for overdoped cuprates. The specific topics addressed in this thesis are as follows. 1. Topological insulators are materials exhibiting a novel quantum state of matter; these insulators are characterized by a bulk excitation generated by the spin orbit interaction, and protected conducting states on their edge or surface. In this work we investigate in detail the electronic structure of a series of ternary half-Heusler compounds MM'X of MgAgAS-type with M = (Lu, La, Sc, Y) and M'X=(PtBi,AuPb,PdBi,PtSb,AuSn,NiBi,PdSb). The characteristic features of all half-Heusler compounds considered here are topological nontrivial semimetal, or nontrivial metal, or trivial insulator. The analysis of the relation among the band inversion strength (distance from the critical line), atomic number of constituents, and lattice constant could provide a methodology (a rule of thumb) to predict the topological order of hypothetical nonmagnetic half-Heusler compound more generally. 2. The bulk Fermi surface (FS) is observed in an overdoped ( x=0.3) single crystal of La2-xSrxCuO4 by using Compton scattering. A 2-D momentum density reconstruction from measured Compton profiles yields a clear FS signature in the third Brillouin zone along [100]. The quantitative agreement between density functional theory calculations and momentum density experiment suggests that Fermi-liquid physics is restored in the overdoped regime. The FS shows signs of a change topological of the FS found at lower doping. We find similar quantitative agreement between the measured 2D angular correlation of positron annihilation radiation (2D-ACAR) spectra and DFT simulations. However, 2D-ACAR does not give such a clear signature of the FS in the extended momentum space in either theory or experiment.

  17. Peculiarity of interrelation between electronic and magnetic properties of HTSC cuprates associated with short-range antiferromagnetic order

    SciTech Connect

    Ovchinnikov, S. G. Korshunov, M. M.; Kozeeva, L. P.; Lavrov, A. N.

    2010-07-15

    We report on the results of measurements of anisotropic resistivity of RBa{sub 2}Cu{sub 3}O{sub 6+x} (R = Tm, Lu) high-temperature superconducting single crystals in a wide range of doping levels, indicating a nontrivial effect of magnetic order on the electronic properties of cuprates. In particular, our results visually demonstrate the crossover from the state with moderate anisotropy of resistivity {rho}{sub c}/{rho}{sub ab} {approx} 30 to a strongly anisotropic state with {rho}{sub c}/{rho}{sub ab} {approx} 7 x 10{sup 3} upon cooling as well as upon a decrease in the hole concentration in the CuO{sub 2} planes. It is also shown that anisotropy is sensitive to the magnetic state of CuO{sub 2} planes and attains its maximum value after the establishment of the long-range antiferromagnetic order. The results are discussed in the framework of the theory based on the t-t'-t''-J model of CuO{sub 2} layers taking into account strong electron correlations and short-range magnetic order. In this theory, anomalies of spin correlators and Fermi surface topology for a critical hole concentration of p* {approx} 0.24 are demonstrated. The concentration dependence of the charge carrier energy indicates partial suppression of energy due to the emergence of a pseudogap at p < p*. This theory explains both the experimentally observed sensitivity of anisotropy in conductivity to the establishment of the antiferromagnetic order and the absence of anomalies in the temperature dependence of resistivity {rho}{sub ab}(T) in the vicinity of the Neel temperature.

  18. NASA 2014: Earth

    NASA Video Gallery

    For the first time in more than a decade, five NASA Earth science missions will be launched into space in the same year, opening new and improved remote eyes to monitor our changing planet. The lau...

  19. The Earth Tides.

    ERIC Educational Resources Information Center

    Levine, Judah

    1982-01-01

    In addition to oceans, the earth is subjected to tidal stresses and undergoes tidal deformations. Discusses origin of tides, tidal stresses, and methods of determining tidal deformations (including gravity, tilt, and strain meters). (JN)

  20. Earth Radiation Measurement Science

    NASA Technical Reports Server (NTRS)

    Smith, G. Louis

    2000-01-01

    This document is the final report for NASA Grant NAG1-1959, 'Earth Radiation Measurement Science'. The purpose of this grant was to perform research in this area for the needs of the Clouds and Earth Radiant Energy System (CERES) project and for the Earth Radiation Budget Experiment (ERBE), which are bing conducted by the Radiation and Aerosols Branch of the Atmospheric Sciences Division of Langley Research Center. Earth Radiation Measurement Science investigates the processes by which measurements are converted into data products. Under this grant, research was to be conducted for five tasks: (1) Point Response Function Measurements; (2) Temporal Sampling of Outgoing Longwave Radiation; (3) Spatial Averaging of Radiation Budget Data; (4) CERES Data Validation and Applications; and (5) ScaRaB Data Validation and Application.

  1. Beautiful Earth with GPM

    NASA Video Gallery

    This is a musical and visual tour of Earth from space followed by a discussion with scientists from NASA's new rain and snow satellite. During this one-hour event, students and teachers from across...

  2. Earth Reconnect -- July 2012

    NASA Video Gallery

    A visualization of Earth's magnetosphere on July 15-16, 2012, shows how constant magnetic reconnection caused by an arriving coronal mass ejection, or CME, from the sun disrupted the magnetosphere,...

  3. Energy for Planet Earth.

    ERIC Educational Resources Information Center

    Davis, Ged R.

    1990-01-01

    Examined is the world society's ability to meet energy needs without destroying the earth. Supply and demand issues are examined. International per capita energy use is compared. Historical trends are described. (CW)

  4. LANL Studies Earth's Magnetosphere

    ScienceCinema

    Daughton, Bill

    2014-08-12

    A new 3-D supercomputer model presents a new theory of how magnetic reconnection works in high-temperature plasmas. This Los Alamos National Laboratory research supports an upcoming NASA mission to study Earth's magnetosphere in greater detail than ever.

  5. Mapping Earth Science Concepts.

    ERIC Educational Resources Information Center

    McDuffie, Thomas E., Jr.; Van Dine, William E.

    1978-01-01

    Presents two experiments concerned with mapping skills. Directions are given for calculating the circumference of the earth and for developing a model of the solar system using familiar territory as a frame of reference. (MA)

  6. Down to earth relativity

    NASA Technical Reports Server (NTRS)

    Shapiro, I. I.

    1978-01-01

    The basic concepts of the special and general theories of relativity are described. Simple examples are given to illustrate the effect of relativity on measurements of time and frequency in the near-earth environment.

  7. The Whole Earth Dialogue.

    ERIC Educational Resources Information Center

    Schneider, Stephen H.

    1988-01-01

    Discusses the trend toward more "earth-as-a-system" approaches in research and teaching about global science. Uses the "greenhouse effect" as a prototypical global change problem that requires interdisciplinary problem-solving approaches. (TW)

  8. Geophysics: Earth's core problem

    NASA Astrophysics Data System (ADS)

    Dobson, David

    2016-06-01

    Measurements of the electrical resistance and thermal conductivity of iron at extreme pressures and temperatures cast fresh light on controversial numerical simulations of the properties of Earth's outer core. See Letters p.95 & 99

  9. Managing Planet Earth.

    ERIC Educational Resources Information Center

    Clark, William C.

    1989-01-01

    Discusses the human use of the planet earth. Describes the global patterns and the regional aspects of change. Four requirements for the cultivation of leadership and institutional competence are suggested. Lists five references for further reading. (YP)

  10. LANL Studies Earth's Magnetosphere

    SciTech Connect

    Daughton, Bill

    2011-04-15

    A new 3-D supercomputer model presents a new theory of how magnetic reconnection works in high-temperature plasmas. This Los Alamos National Laboratory research supports an upcoming NASA mission to study Earth's magnetosphere in greater detail than ever.

  11. Welcome Back to Earth

    NASA Video Gallery

    NASA astronaut Scott Kelly is interviewed by public affairs officer Rob Navias just after returning to Earth aboard a Soyuz spacecraft on March 1, 2016 (March 2, local Kazakh time) following a 340 ...

  12. Observing earth from Skylab

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Skylab technology and observations of earth resources are discussed. Special attention was given to application of Skylab data to mapmaking, geology/geodesy, water resources, oceanography, meteorology, and geography/ecology.

  13. Earth study from space

    NASA Technical Reports Server (NTRS)

    Sidorenko, A. V.

    1981-01-01

    The significance that space studies are making to all Earth sciences in the areas of geography, geodesy, cartography, geology, meteorology, oceanology, agronomy, and ecology is discussed. It is predicted that cosmonautics will result in a revolution in science and technology.

  14. Skylab Earth Observation Studies

    NASA Technical Reports Server (NTRS)

    1972-01-01

    This concept illustrates Skylab Earth observation studies, an Earth Resources Experiment Package (EREP). EREP was designed to explore the use of the widest possible portion of the electromagnetic spectrum for Earth resource investigations with sensors that recorded data in the visible, infrared, and microwave spectral regions. Resources subject to this study included a capability of mapping Earth resources and land uses, crop and forestry cover, health of vegetation, types of soil, water storage in snow pack, surface or near-surface mineral deposits, sea surface temperature, and the location of likely feeding areas for fish, etc. A significant feature of EREP was the ability of man to operate the sensors in a laboratory fashion.

  15. Earth's variable rotation

    NASA Technical Reports Server (NTRS)

    Hide, Raymond; Dickey, Jean O.

    1991-01-01

    Recent improvements in geodetic data and practical meteorology have advanced research on fluctuations in the earth's rotation. The interpretation of these fluctuations is inextricably linked with studies of the dynamics of the earth-moon system and dynamical processes in the liquid metallic core of the earth (where the geomagnetic field originates), other parts of the earth's interior, and the hydrosphere and atmosphere. Fluctuations in the length of the day occurring on decadal time scales have implications for the topographay of the core-mantle boundary and the electrical, magnetic, ande other properties of the core and lower mantle. Investigations of more rapid fluctuations bear on meteorological studies of interannual, seasonal, and intraseasonal variations in the general circulation of the atmosphere and the response of the oceans to such variations.

  16. Solar System Portrait - Earth

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This image of the Earth is one of 60 frames taken by the Voyager 1 spacecraft on Feb. 14, 1990 from a distance of approximately 4 billion miles and about 32 degrees above the ecliptic plane. This image the Earth is a mere point of light, a crescent only 0.12 pixel in size. Our planet was caught in the center of one of the scattered light rays resulting from taking the image so close to the sun.

  17. NASA Earth science missions

    NASA Astrophysics Data System (ADS)

    Neeck, Steven P.; Volz, Stephen M.

    2013-10-01

    NASA's Earth Science Division (ESD) conducts pioneering work in Earth system science, the interdisciplinary view of Earth that explores the interaction among the atmosphere, oceans, ice sheets, land surface interior, and life itself that has enabled scientists to measure global and climate changes and to inform decisions by governments, organizations, and people in the United States and around the world. The ESD makes the data collected and results generated by its space missions accessible to other agencies and organizations to improve the products and services they provide, including air quality indices, disaster management, agricultural yield projections, and aviation safety. Through partnerships with national and international agencies, NASA enables the application of this understanding. The ESD's Flight Program provides the spacebased observing systems and supporting ground segment infrastructure for mission operations and scientific data processing and distribution that support NASA's Earth system science research and modeling activities. The Flight Program currently has 15 operating Earth observing space missions, including the recently launched Landsat-8/Landsat Data Continuity Mission (LDCM). The ESD has 16 more missions planned for launch over the next decade. These include first and second tier missions from the 2007 Earth Science Decadal Survey, Climate Continuity missions to assure availability of key data sets needed for climate science and applications, and small-sized competitively selected orbital missions and instrument missions of opportunity utilizing rideshares that are part of the Earth Venture (EV) Program. The recently selected Cyclone Global Navigation Satellite System (CYGNSS) microsatellite constellation and the Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument are examples. In addition, the International Space Station (ISS) is being increasingly used to host NASA Earth observing science instruments. An overview of plans

  18. Earth and Space Science

    NASA Technical Reports Server (NTRS)

    Meeson, Blanche W.

    1999-01-01

    Workshop for middle and high school teachers to enhance their knowledge of the Earth as a system. NASA data and materials developed by teachers (all available via the Internet) will be used to engage participants in hands-on, investigative approaches to the Earth system. All materials are ready to be applied in pre-college classrooms. Remotely-sensed data will be used in combination with familiar resources, such as maps, to examine global climate change.

  19. Skylab explores the Earth

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Data from visual observations are integrated with results of analyses of approxmately 600 of the nearly 2000 photographs taken of Earth during the 84-day Skylab 4 mission to provide additional information on (1) Earth features and processes; (2) operational procedures and constraints in observing and photographing the planet; and (3) the use of man in real-time analysis of oceanic and atmospheric phenomena.

  20. Guided earth boring tool

    SciTech Connect

    Mc Donald, W.J.; Pittard, G.T.; Maurer, W.C.; Wasson, M.R.; Herben, W.C.

    1987-09-22

    A controllable tool for drilling holes in the earth is described comprising a hollow elongated rigid supporting drill pipe having a forward end for entering the earth, means supporting the drill pipe for earth boring or piercing movement, including means for moving the drill pipe longitudinally for penetrating the earth, the drill pipe moving means being constructed to permit addition and removal of supporting drill pipe during earth penetrating operation, a boring mole supported on the forward end of the hollow low drill pipe comprising a cylindrical housing supported on and open to the forward end of the drill pipe, a first means on the front end for applying a boring force to the soil comprising an anvil having a striking surface inside the housing and a boring surface outside the housing, a second means comprising a reciprocally movable hammer positioned in the housing to apply a percussive force to the anvil striking surface for transmitting a percussive force to the boring force applying means, and means permitting introduction of air pressure supplied through the hollow pipe into the housing for operating the hammer and for discharging spent air from the housing to the hole being bored, and the tool being operable to penetrate the earth upon longitudinal movement of the drill rod by the longitudinal rod moving means and operation of the mole by reciprocal movement of the hammer.

  1. Biosignatures of early earths

    NASA Technical Reports Server (NTRS)

    Pilcher, Carl B.

    2003-01-01

    A major goal of NASA's Origins Program is to find habitable planets around other stars and determine which might harbor life. Determining whether or not an extrasolar planet harbors life requires an understanding of what spectral features (i.e., biosignatures) might result from life's presence. Consideration of potential biosignatures has tended to focus on spectral features of gases in Earth's modern atmosphere, particularly ozone, the photolytic product of biogenically produced molecular oxygen. But life existed on Earth for about 1(1/2) billion years before the buildup of atmospheric oxygen. Inferred characteristics of Earth's earliest biosphere and studies of modern microbial ecosystems that share some of those characteristics suggest that organosulfur compounds, particularly methanethiol (CH(3)SH, the sulfur analog of methanol), may have been biogenic products on early Earth. Similar production could take place on extrasolar Earth-like planets whose biota share functional chemical characteristics with Earth life. Since methanethiol and related organosulfur compounds (as well as carbon dioxide) absorb at wavelengths near or overlapping the 9.6-microm band of ozone, there is potential ambiguity in interpreting a feature around this wavelength in an extrasolar planet spectrum.

  2. Biosignatures of Early Earths

    NASA Astrophysics Data System (ADS)

    Pilcher, Carl B.

    2003-11-01

    A major goal of NASA's Origins Program is to find habitable planets around other stars and determine which might harbor life. Determining whether or not an extrasolar planet harbors life requires an understanding of what spectral features (i.e., biosignatures) might result from life's presence. Consideration of potential biosignatures has tended to focus on spectral features of gases in Earth's modern atmosphere, particularly ozone, the photolytic product of biogenically produced molecular oxygen. But life existed on Earth for about 1½ billion years before the buildup of atmospheric oxygen. Inferred characteristics of Earth's earliest biosphere and studies of modern microbial ecosystems that share some of those characteristics suggest that organosulfur compounds, particularly methanethiol (CH3SH, the sulfur analog of methanol), may have been biogenic products on early Earth. Similar production could take place on extrasolar Earth-like planets whose biota share functional chemical characteristics with Earth life. Since methanethiol and related organosulfur compounds (as well as carbon dioxide) absorb at wavelengths near or overlapping the 9.6-μm band of ozone, there is potential ambiguity in interpreting a feature around this wavelength in an extrasolar planet spectrum.

  3. Toward other Earths

    NASA Astrophysics Data System (ADS)

    Hatzes, Artie P.

    2016-04-01

    How common are habitable Earth-like planets? This is a key question that drives much of current research in exoplanets. To date, we have discovered over one thousand exoplanets, mostly through the transit method. Among these are Earth-size planets, but these orbit very close to the star (semi-major axis approximately 0.01 Astronomical Units). Potentially rocky planets have also been discovered in a star's habitable zone, but these have approximately twice the radius of the Earth. These certainly do not qualify as Earth "twins". Several hundreds of multi-planet systems have also been discovered, but these are mostly ultra-compact systems with up to seven planets all with orbital distances less than that of Mercury in our solar system. The detection of a planetary system that is the direct analog of our solar system still eludes us. After an overview of the current status of exoplanet discoveries I will discuss the prospects and challenges of finding such Earth analogs from the ground and from future space missions like PLATO. After over two decades of searching, we may well be on the brink of finding other Earths.

  4. Mission to Planet Earth

    NASA Technical Reports Server (NTRS)

    Tilford, Shelby G.; Koczor, Ron; Lee, Jonathan; Grady, Kevin J.; Hudson, Wayne R.; Johnston, Gordon I.; Njoku, Eni G.

    1990-01-01

    To preserve the earth, it is necessary to understand the tremendously complex interactions of the atmosphere, oceans, land, and man's activities deeply enough to construct models that can predict the consequences of our actions and help us make sound environmental, energy, agriculture, and economic decisions. Mission to Planet Earth is NASA's suggested share and the centerpiece of the U.S. contribution to understanding the environment, the Global Change Research Program. The first major element of the mission would be the Earth Observing System, which would give the simultaneous, comprehensive, long-term earth coverage lacking previously. NASA's Geosynchronous Earth Observatory with two additional similar spacecraft would be orbited by the U.S., plus one each by Japan and the European Space Agency. These would be the first geostationary satellites to span all the disciplines of the earth sciences. A number of diverse data gathering payloads are also planned to be carried aboard the Polar Orbiting Platform. Making possible the long, continuous observations planned and coping with the torrent of data acquired will require technical gains across a wide front. Finally, how all this data is consolidated and disseminated by the EOS Data and Information System is discussed.

  5. Global Images of Earth

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Global images of Earth from Galileo. In each frame, the continent of Antarctica is visible at the bottom of the globe. South America may be seen in the first frame (top left), the great Pacific Ocean in the second (bottom left), India at the top and Australia to the right in the third (top right), and Africa in the fourth (bottom right). Taken at six-hour intervals on December 11, 1990, at a range of between 2 and 2.7 million kilometers (1.2 to 1.7 million miles). P-37630

    These images were taken during Galileo's first Earth flyby. This gravity assist increased Galileo's speed around the Sun by about 5.2 kilometers per second (or 11,600 miles per hour) and substantially redirected Galileo as required for its flybys of the asteroid Gaspra in October 1991 and Earth in 1992. Galileo's closest approach (960 kilometers, or 597 miles, above the Earth's surface) to the Earth was on December 8, 1990, 3 days before these pictures were taken.

    Each of these images is a color composite, made up using images taken through red, green, and violet filters. The four images are part of the Galileo Earth spin movie, a 256-frame time-lapse motion picture that shows a 25-hour period of Earth's rotation and atmospheric dynamics. The movie gives scientists a unique overall view of global weather patterns, as opposed to the limited view of weather satellite images.

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA'is Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.

  6. Mapping the Electronic Structure of Each Ingredient Oxide Layer of High-T\\{c} Cuprate Superconductor Bi{2}Sr{2}CaCu{2}O{8+δ}.

    PubMed

    Lv, Yan-Feng; Wang, Wen-Lin; Peng, Jun-Ping; Ding, Hao; Wang, Yang; Wang, Lili; He, Ke; Ji, Shuai-Hua; Zhong, Ruidan; Schneeloch, John; Gu, Gen-Da; Song, Can-Li; Ma, Xu-Cun; Xue, Qi-Kun

    2015-12-01

    Understanding the mechanism of high transition temperature (T{c}) superconductivity in cuprates has been hindered by the apparent complexity of their multilayered crystal structure. Using a cryogenic scanning tunneling microscopy (STM), we report on layer-by-layer probing of the electronic structures of all ingredient planes (BiO, SrO, CuO{2}) of Bi{2}Sr{2}CaCu_2}O{8+δ} superconductor prepared by argon-ion bombardment and annealing technique. We show that the well-known pseudogap (PG) feature observed by STM is inherently a property of the BiO planes and thus irrelevant directly to Cooper pairing. The SrO planes exhibit an unexpected van Hove singularity near the Fermi level, while the CuO{2} planes are exclusively characterized by a smaller gap inside the PG. The small gap becomes invisible near T{c}, which we identify as the superconducting gap. The above results constitute severe constraints on any microscopic model for high T{c} superconductivity in cuprates. PMID:26684137

  7. Mapping the Electronic Structure of Each Ingredient Oxide Layer of High-Tc Cuprate Superconductor Bi2 Sr2 CaCu2 O8 +δ

    NASA Astrophysics Data System (ADS)

    Lv, Yan-Feng; Wang, Wen-Lin; Peng, Jun-Ping; Ding, Hao; Wang, Yang; Wang, Lili; He, Ke; Ji, Shuai-Hua; Zhong, Ruidan; Schneeloch, John; Gu, Gen-Da; Song, Can-Li; Ma, Xu-Cun; Xue, Qi-Kun

    2015-12-01

    Understanding the mechanism of high transition temperature (Tc) superconductivity in cuprates has been hindered by the apparent complexity of their multilayered crystal structure. Using a cryogenic scanning tunneling microscopy (STM), we report on layer-by-layer probing of the electronic structures of all ingredient planes (BiO, SrO, CuO2 ) of Bi2 Sr2 CaCu2 O8 +δ superconductor prepared by argon-ion bombardment and annealing technique. We show that the well-known pseudogap (PG) feature observed by STM is inherently a property of the BiO planes and thus irrelevant directly to Cooper pairing. The SrO planes exhibit an unexpected van Hove singularity near the Fermi level, while the CuO2 planes are exclusively characterized by a smaller gap inside the PG. The small gap becomes invisible near Tc, which we identify as the superconducting gap. The above results constitute severe constraints on any microscopic model for high Tc superconductivity in cuprates.

  8. Angle-Resolved Photoelectron Spectroscopy Studies of the Many-Body Effects in the Electronic Structure of High-Tc Cuprates

    NASA Astrophysics Data System (ADS)

    Inosov, D. S.

    2008-07-01

    After an extended introduction, the thesis considers the electronic properties of BSCCO and the recent progress in understanding the electronic structure of this material. The main result of this part of the work is a model of the Green's function that is later used for calculating the two-particle excitation spectrum. Then, the matrix element effects in the photoemission spectra of cuprates are discussed with a focus on the recently discovered anomalous behavior of the ARPES spectra that partially originates from the momentum-dependent photoemission matrix element. The momentum- and excitation energy dependence of the anomalous high-energy dispersion, termed "waterfalls", is covered in full detail. Finally, the work describes the relation of ARPES with other experimental methods, such as INS spectroscopy. For the optimally doped bilayer Bi-based cuprate, the renormalized two-particle correlation function in the superconducting state is calculated from ARPES data within an itinerant model based on the random phase approximation (RPA). Additionally, two other applications of the same approach are briefly sketched: the relation of ARPES to FT-STS, and the nesting properties of Fermi surfaces in two-dimensional charge density wave compounds.

  9. Uniform mixing of high- Tc superconductivity and antiferromagnetism on a single CuO 2 plane in five-layered cuprates

    NASA Astrophysics Data System (ADS)

    Mukuda, H.; Abe, M.; Kitaoka, Y.; Kotegawa, H.; Tokiwa, K.; Watanabe, T.; Iyo, A.; Kito, H.; Tanaka, Y.; Kodama, Y.

    2007-09-01

    We report systematic Cu-NMR studies on five-layered cuprates from under-doped HgBa2Ca4Cu5O12+δ (Hg-1245(UD)) to slightly overdoped Tl-1245(OVD), and compare with optimally-doped Hg-1245(OPT). In the under-doped Hg-1245(UD), antiferromagnetism (AFM) has been found to take place at TN = 290 K, exhibiting a large antiferromagnetic moment of 0.67-0.69 μB at three inner planes (IP's). These values are comparable to that reported for non-doped cuprates, suggesting that the IP's may be in a nearly non-doped regime. Most surprisingly, the AFM order is also detected with MAFM(OP) = 0.1 μB even at two outer planes (OP's) that are responsible for the onset of superconductivity (SC) with Tc = 72 K. The high-Tc SC at Tc = 72 K can uniformly coexist on a microscopic level with the AFM at OP's. This is the first microscopic evidence for the uniformly mixed phase of AFM and SC on a single CuO2 plane. Although, the AFM/SC mixed CuO2 planes are significantly separated by three non-doped AFM layers, the onset of AFM does not prevent the occurrence of SC with the high value of Tc = 72 K.

  10. Large and high-quality single-crystal growth of cuprate superconductor Bi-2223 using the traveling-solvent floating-zone (TSFZ) method

    NASA Astrophysics Data System (ADS)

    Adachi, Shintaro; Usui, Tomohiro; Kosugi, Kenta; Sasaki, Nae; Sato, Kentaro; Fujita, Masaki; Yamada, Kazuyoshi; Fujii, Takenori; Watanabe, Takao

    In high superconducting transition temperature (high-Tc) cuprates, it is empirically known that Tc increases on increasing the number of CuO2 planes in a unit cell n from 1 to 3. Bi-family cuprates are ideal for investigating the microscopic mechanism involved. However, it is difficult to grow tri-layered Bi-2223, probably owing to its narrow crystallization field. Here, we report improved crystal growth of this compound using the TSFZ method under conditions slightly different from those in an earlier report [J. Cryst. Growth 223, 175 (2001)]. A Bi-rich feed-rod composition of Bi2.2Sr1.9Ca2Cu3Oy and a slightly oxygen-reduced atmosphere (mixed gas flow of O2 (10%) and Ar (90%)) were adopted for the crystal growth. In addition, to increase the supersaturation of the melts, we applied a large temperature gradient along the solid-liquid interface by shielding a high-angle light beam using Al foil around the quartz tube. In this way, we succeeded in preparing large (2 × 2 × 0 . 05 mm3) and high-quality (almost 100% pure) Bi-2223 single crystals. Hirosaki University Grant for Exploratory Research by Young Scientists and Newly-appointed Scientists.

  11. Ordered state of magnetic charge in the pseudo-gap phase of a cuprate superconductor (HgBa2CuO4+δ )

    NASA Astrophysics Data System (ADS)

    Lovesey, S. W.; Khalyavin, D. D.

    2015-12-01

    A symmetry-based interpretation of published experimental results demonstrates that the pseudo-gap phase of underdoped HgBa2CuO4+δ (Hg1201) possesses an ordered state of magnetic charge epitomized by Cu magnetic monopoles. Magnetic properties of one-layer Hg1201 and two-layer YBa2Cu3O6+x (YBCO) cuprates have much in common, because their pseudo-gap phases possess the same magnetic space-group, e.g. both underdoped cuprates allow the magneto-electric (Kerr) effect. Differences in their properties stem from different Cu site symmetries, leaving Cu magnetic monopoles forbidden in YBCO. Resonant x-ray Bragg diffraction experiments can complement the wealth of information available from neutron diffraction experiments on five Hg1201 samples on which our findings are based. In the case of Hg1201 emergence of the pseudo-gap phase, with time-reversal violation, is accompanied by a reduction of Cu site symmetry that includes loss of a centre of inversion symmetry. In consequence, parity-odd x-ray absorption events herald the onset of the enigmatic phase, and we predict dependence of corresponding Bragg spots on magneto-electric multipoles, including the monopole, and the azimuthal angle (crystal rotation about the Bragg wavevector).

  12. Growth and Study of Cuprate Thin Film Heterostructures Combining La2CuO4+δ and LaCuO3-δ

    NASA Astrophysics Data System (ADS)

    Marmol, Rodrigo; Burquest, Franklin; Cox, Nicholas; Nelson-Cheeseman, Brittany

    Cuprate materials have shown promise as fuel cell cathode materials. Both the layered perovskite, La2CuO4+δ, and its 3D perovskite counterpart, LaCuO3-δ, demonstrate the simultaneous electronic and ionic conduction necessary for fuel cell cathode materials. The layered perovskite allows for oxygen interstitial diffusion through the material. Meanwhile, the 3D perovskite readily creates oxygen vacancies, allowing for oxygen vacancy diffusion through the material. In this work, we investigate thin film heterostructures created from these two disparate materials to understand how the local oxygen diffusion phenomena affect the local structure and electrical transport of cuprates. The growth of these heterostructures is possible through the atomic monolayer control of Molecular Beam Epitaxy with in-situ monitoring via Reflective High Energy Electron Diffraction. The superlattice structure is characterized by x-ray reflectivity, and the crystal structure of the disparate phases is characterized by x-ray diffraction. A custom electrical transport system is used to characterize the electrical transport of the films. We compare these heterostructures with the single-phase films of La2CuO4+δand LaCuO3-δin order to understand how this heterostructuring may modify the structure and electrical properties.

  13. Ferro-type order of magneto-electric quadrupoles as an order-parameter for the pseudo-gap phase of a cuprate superconductor.

    PubMed

    Lovesey, S W; Khalyavin, D D; Staub, U

    2015-07-29

    There is general agreement within the community of researchers that investigate high-Tc materials that it is most important to understand the pseudo-gap phase. To this end, many experiments on various cuprates have been reported. Two prominent investigations-Kerr effect and neutron Bragg diffraction-imply that underdoped YBCO samples possess long-range magnetic order of an unusual kind. However, other measurements do not support the existence of magnetic order. Here we show that the Kerr effect and magnetic Bragg diffraction data are individual manifestations of ordered magneto-electric quadrupoles at Cu sites. While the use of magneto-electric multipoles is new in studies of the electronic properties of cuprates, they are not unknown in other materials, including an investigation with x-rays of the parent compound CuO. We exploit the recent prediction that neutrons are deflected by magneto-electric multipoles. The outcome of our study is a theory for the order-parameter of the pseudo-gap phase without the aforementioned conflict with other measurements, and the first experimental evidence that neutrons interact with multipoles belonging to a state of magnetic charge. PMID:26153665

  14. Ordered state of magnetic charge in the pseudo-gap phase of a cuprate superconductor (HgBa2CuO(4+δ)).

    PubMed

    Lovesey, S W; Khalyavin, D D

    2015-12-16

    A symmetry-based interpretation of published experimental results demonstrates that the pseudo-gap phase of underdoped HgBa2CuO(4+δ) (Hg1201) possesses an ordered state of magnetic charge epitomized by Cu magnetic monopoles. Magnetic properties of one-layer Hg1201 and two-layer YBa2Cu3O(6+x) (YBCO) cuprates have much in common, because their pseudo-gap phases possess the same magnetic space-group, e.g. both underdoped cuprates allow the magneto-electric (Kerr) effect. Differences in their properties stem from different Cu site symmetries, leaving Cu magnetic monopoles forbidden in YBCO. Resonant x-ray Bragg diffraction experiments can complement the wealth of information available from neutron diffraction experiments on five Hg1201 samples on which our findings are based. In the case of Hg1201 emergence of the pseudo-gap phase, with time-reversal violation, is accompanied by a reduction of Cu site symmetry that includes loss of a centre of inversion symmetry. In consequence, parity-odd x-ray absorption events herald the onset of the enigmatic phase, and we predict dependence of corresponding Bragg spots on magneto-electric multipoles, including the monopole, and the azimuthal angle (crystal rotation about the Bragg wavevector). PMID:26575373

  15. Coexistence of ΘI I-loop-current order with checkerboard d -wave CDW/PDW order in a hot-spot model for cuprate superconductors

    NASA Astrophysics Data System (ADS)

    de Carvalho, Vanuildo S.; Pépin, Catherine; Freire, Hermann

    2016-03-01

    We investigate the strong influence of the ΘI I-loop-current order on both unidirectional and bidirectional d -wave charge-density-wave/pair-density-wave (CDW/PDW) composite orders along axial momenta (±Q0,0 ) and (0 ,±Q0) that emerge in an effective hot-spot model departing from the three-band Emery model relevant to the phenomenology of the cuprate superconductors. This study is motivated by the compelling evidence that the ΘI I-loop-current order described by this model may explain groundbreaking experiments such as spin-polarized neutron scattering performed in these materials. Here, we demonstrate, within a saddle-point approximation, that the ΘI I-loop-current order clearly coexists with bidirectional (i.e., checkerboard) d -wave CDW and PDW orders along axial momenta, but is visibly detrimental to the unidirectional (i.e., stripe) case. This result has potentially far-reaching implications for the physics of the cuprates and agrees well with very recent x-ray experiments on YBCO that indicate that at higher dopings the CDW order has indeed a tendency to be bidirectional.

  16. Physics of Ultrathin Films and Heterostructures of Rare-Earth Nickelates

    NASA Astrophysics Data System (ADS)

    Middey, S.; Chakhalian, J.; Mahadevan, P.; Freeland, J. W.; Millis, A. J.; Sarma, D. D.

    2016-07-01

    The electronic structure of transition metal oxides featuring correlated electrons can be rationalized within the Zaanen-Sawatzky-Allen framework. Following a brief description of the present paradigms of electronic behavior, we focus on the physics of rare-earth nickelates as an archetype of complexity emerging within the charge transfer regime. The intriguing prospect of realizing the physics of high-Tc cuprates through heterostructuring resulted in a massive endeavor to epitaxially stabilize these materials in ultrathin form. A plethora of new phenomena unfolded in such artificial structures due to the effect of epitaxial strain, quantum confinement, and interfacial charge transfer. Here we review the present status of artificial rare-earth nickelates in an effort to uncover the interconnection between the electronic and magnetic behavior and the underlying crystal structure. We conclude by discussing future directions to disentangle the puzzle regarding the origin of the metal-insulator transition, the role of oxygen holes, and the true nature of the antiferromagnetic spin configuration in the ultrathin limit.

  17. Venus, Earth, Xenon

    NASA Astrophysics Data System (ADS)

    Zahnle, K. J.

    2013-12-01

    Xenon has been regarded as an important goal of many proposed missions to Venus. This talk is intended to explain why. Despite its being the heaviest gas found in natural planetary atmospheres, there is more evidence that Xe escaped from Earth than for any element apart from helium: (i) Atmospheric Xe is very strongly mass fractionated (at about 4% per amu) from any known solar system source. This suggests fractionating escape that preferentially left the heavy Xe isotopes behind. (ii) Xe is underabundant compared to Kr, a lighter noble gas that is not strongly mass fractionated in air. (iii) Radiogenic Xe is strongly depleted by factors of several to ~100 compared to the quantities expected from radioactive decay of primordial solar system materials. In these respects Xe on Mars is similar to Xe on Earth, but with one key difference: Xe on Mars is readily explained by a simple process like hydrodynamic escape that acts on an initially solar or meteoritic Xe. This is not so for Earth. Earth's Xe cannot be derived by an uncontrived mass fractionating process acting on any known type of Solar System Xe. Earth is a stranger, made from different stuff than any known meteorite or Mars or even the Sun. Who else is in Earth's family? Comets? We know nothing. Father Zeus? Data from Jupiter are good enough to show that jovian Xe is not strongly mass-fractionated but not good enough to determine whether Jupiter resembles the Earth or the Sun. Sister Venus? Noble gas data from Venus are incomplete, with Kr uncertain and Xe unmeasured. Krypton was measured by several instruments on several spacecraft. The reported Kr abundances are discrepant and were once highly controversial. These discrepancies appear to have been not so much resolved as forgotten. Xenon was not detected on Venus. Upper limits were reported for the two most abundant xenon isotopes 129Xe and 132Xe. From the limited data it is not possible to tell whether Venus's affinities lie with the solar wind, or with

  18. Modeling the earth system

    SciTech Connect

    Ojima, D.

    1992-12-31

    The 1990 Global Change Institute (GCI) on Earth System Modeling is the third of a series organized by the Office for Interdisciplinary Earth Studies to look in depth at particular issues critical to developing a better understanding of the earth system. The 1990 GCI on Earth System Modeling was organized around three themes: defining critical gaps in the knowledge of the earth system, developing simplified working models, and validating comprehensive system models. This book is divided into three sections that reflect these themes. Each section begins with a set of background papers offering a brief tutorial on the subject, followed by working group reports developed during the institute. These reports summarize the joint ideas and recommendations of the participants and bring to bear the interdisciplinary perspective that imbued the institute. Since the conclusion of the 1990 Global Change Institute, research programs, nationally and internationally, have moved forward to implement a number of the recommendations made at the institute, and many of the participants have maintained collegial interactions to develop research projects addressing the needs identified during the two weeks in Snowmass.

  19. Monitoring the Earth

    NASA Astrophysics Data System (ADS)

    Vita-Finzi, Claudio

    2003-02-01

    Monitoring the Earth is the first book to review the recent advances in satellite technology, computing and mass spectrometry that are opening up completely new avenues of enquiry to Earth scientists. Among the geological changes that were previously considered too slow or too extensive for direct measurements and that can now be monitored directly are continental displacements, mountain uplift, the growth and decay of icesheets and glaciers, the faulting and folding of rocks, the progress of weathering and sedimentation, and the growth of coral reefs. In addition to these developments, the book assesses progress in fields not normally considered part of physical geology, such as the shape and orbit of the gravity and the terrestrial magnetic field. The results from the new findings are already helping Earth scientists analyze and explain the underlying mechanisms, notably with regard to the storage and release of strain during earthquakes and the interaction of glacial history with the Earth's rate of rotation. The outcoe is a foretaste of the physical geology of the space age.^Fully illustrated with line drawings and photographs, and with a bibliography that encompasses the scattered and disparate litarature, Monitoring the Earth is intended for undergraduates in geology, geomorphology, geomatic engineering and planetary science, but it should also be of interest to astronomers and historians of science.

  20. Earth - Moon Conjunction

    NASA Technical Reports Server (NTRS)

    1992-01-01

    On December 16, 1992, 8 days after its encounter with Earth, the Galileo spacecraft looked back from a distance of about 6.2 million kilometers (3.9 million miles) to capture this remarkable view of the Moon in orbit about Earth. The composite photograph was constructed from images taken through visible (violet, red) and near-infrared (1.0-micron) filters. The Moon is in the foreground; its orbital path is from left to right. Brightly colored Earth contrasts strongly with the Moon, which reacts only about one-third as much sunlight as our world. To improve the visibility of both bodies, contrast and color have been computer enhanced. At the bottom of Earth's disk, Antarctica is visible through clouds. The Moon's far side can also be seen. The shadowy indentation in the Moon's dawn terminator--the boundary between its dark and lit sides--is the South Pole-Aitken Basin, one of the largest and oldest lunar impact features. This feature was studied extensively by Galileo during the first Earth flyby in December 1990.

  1. The Sun and Earth

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Natchimuthuk

    2012-01-01

    Thus the Sun forms the basis for life on Earth via the black body radiation it emits. The Sun also emits mass in the form of the solar wind and the coronal mass ejections (CMEs). Mass emission also occurs in the form of solar energetic particles (SEPs), which happens during CMEs and solar flares. Both the mass and electromagnetic energy output of the Sun vary over a wide range of time scales, thus introducing disturbances on the space environment that extends from the Sun through the entire heliosphere including the magnetospheres and ionospheres of planets and moons of the solar system. Although our habitat is located in the neutral atmosphere of Earth, we are intimately connected to the non-neutral space environment starting from the ionosphere to the magnetosphere and to the vast interplanetary space. The variability of the solar mass emissions results in the interaction between the solar wind plasma and the magnetospheric plasma leading to huge disturbances in the geospace. The Sun ionizes our atmosphere and creates the ionosphere. The ionosphere can be severely disturbed by the transient energy input from solar flares and the solar wind during geomagnetic storms. The complex interplay between Earth's magnetic field and the solar magnetic field carried by the solar wind presents varying conditions that are both beneficial and hazardous to life on earth. This seminar presents some of the key aspects of this Sun-Earth connection that we have learned since the birth of space science as a scientific discipline some half a century ago.

  2. "Snowing" Core in Earth?

    NASA Astrophysics Data System (ADS)

    Li, J.; Chen, B.; Cormier, V.; Gao, L.; Gubbins, D.; Kharlamova, S. A.; He, K.; Yang, H.

    2008-12-01

    As a planet cools, an initially molten core gradually solidifies. Solidification occurs at shallow depths in the form of "snow", if the liquidus temperature gradient of the core composition is smaller than the adiabatic temperature gradient in the core. Experimental data on the melting behavior of iron-sulfur binary system suggest that the cores of Mercury and Ganymede are probably snowing at the present time. The Martian core is predicted to snow in the future, provided that the sulfur content falls into the range of 10 to 14 weight percent. Is the Earth's core snowing? If so, what are the surface manifestations? If the Earth's core snowed in the past, how did it affect the formation of the solid inner core and the geodynamo? Here, we evaluate the likelihood and consequences of a snowing core throughout the Earth's history, on the basis of mineral physics data describing the melting behavior, equation-of-state, and thermodynamic properties of iron-rich alloys at high pressures. We discuss if snowing in the present-day Earth can reproduce the shallow gradients of compressional wave velocity above the inner-core boundary, and whether or not snowing in the early Earth may reconcile the apparent young age of the solid inner core with a long-lived geodynamo.

  3. The Earth System Model

    NASA Technical Reports Server (NTRS)

    Schoeberl, Mark; Rood, Richard B.; Hildebrand, Peter; Raymond, Carol

    2003-01-01

    The Earth System Model is the natural evolution of current climate models and will be the ultimate embodiment of our geophysical understanding of the planet. These models are constructed from components - atmosphere, ocean, ice, land, chemistry, solid earth, etc. models and merged together through a coupling program which is responsible for the exchange of data from the components. Climate models and future earth system models will have standardized modules, and these standards are now being developed by the ESMF project funded by NASA. The Earth System Model will have a variety of uses beyond climate prediction. The model can be used to build climate data records making it the core of an assimilation system, and it can be used in OSSE experiments to evaluate. The computing and storage requirements for the ESM appear to be daunting. However, the Japanese ES theoretical computing capability is already within 20% of the minimum requirements needed for some 2010 climate model applications. Thus it seems very possible that a focused effort to build an Earth System Model will achieve succcss.

  4. Crescent Earth and Moon

    NASA Technical Reports Server (NTRS)

    1977-01-01

    This picture of a crescent-shaped Earth and Moon -- the first of its kind ever taken by a spacecraft -- was recorded Sept. 18, 1977, by NASA's Voyager 1 when it was 7.25 million miles (11.66 million kilometers) from Earth. The Moon is at the top of the picture and beyond the Earth as viewed by Voyager. In the picture are eastern Asia, the western Pacific Ocean and part of the Arctic. Voyager 1 was directly above Mt. Everest (on the night side of the planet at 25 degrees north latitude) when the picture was taken. The photo was made from three images taken through color filters, then processed by the Jet Propulsion Laboratory's Image Processing Lab. Because the Earth is many times brighter than the Moon, the Moon was artificially brightened by a factor of three relative to the Earth by computer enhancement so that both bodies would show clearly in the print. Voyager 2 was launched Aug. 20, 1977, followed by Voyager 1 on Sept. 5, 1977, en route to encounters at Jupiter in 1979 and Saturn in 1980 and 1981. JPL manages the Voyager mission for NASA's Office of Space Science.

  5. Dagik Earth and IUGONET

    NASA Astrophysics Data System (ADS)

    Ebisawa, K.; Koyama, Y.; Saito, A.; Sakamoto, S.; Ishii, M.; Kumano, Y.; Hazumi, Y.

    2015-09-01

    In this paper we introduce two independent projects in progress in Japan. Dagik Earth is a visualization project of the Earth and planets on a spherical screen using only a standard PC and a projector. Surface images of the Earth or planets (or whatever having spherical shape) in the equirectangular (plate carre) projection are projected on a spherical screen in the orthographic projection. As a result, the spherical screen becomes a virtual digital globe, which can be rotated using mouse or remote controller. Inter-university Upper atmosphere Global Observation NETwork (IUGONET) is a collaboration of five Japanese institutes to build a comprehensive database system for the metadata of the upper-atmospheric data taken by these institutes. We explain the IUGONET metadata database and iUgonet Data Analysis Software (UDAS) for upper atmospheric research.

  6. Better Than Earth

    NASA Astrophysics Data System (ADS)

    Heller, René

    2015-01-01

    Do we inhabit the best of all possible worlds? German mathematician Gottfried Leibniz thought so, writing in 1710 that our planet, warts and all, must be the most optimal one imaginable. Leibniz's idea was roundly scorned as unscientific wishful thinking, most notably by French author Voltaire in his magnum opus, Candide. Yet Leibniz might find sympathy from at least one group of scientists - the astronomers who have for decades treated Earth as a golden standard as they search for worlds beyond our own solar system. Because earthlings still know of just one living world - our own - it makes some sense to use Earth as a template in the search for life elsewhere, such as in the most Earth-like regions of Mars or Jupiter's watery moon Europa. Now, however, discoveries of potentially habitable planets orbiting stars other than our sun - exoplanets, that is - are challenging that geocentric approach.

  7. Earth's Trojan asteroid.

    PubMed

    Connors, Martin; Wiegert, Paul; Veillet, Christian

    2011-07-28

    It was realized in 1772 that small bodies can stably share the same orbit as a planet if they remain near 'triangular points' 60° ahead of or behind it in the orbit. Such 'Trojan asteroids' have been found co-orbiting with Jupiter, Mars and Neptune. They have not hitherto been found associated with Earth, where the viewing geometry poses difficulties for their detection, although other kinds of co-orbital asteroid (horseshoe orbiters and quasi-satellites) have been observed. Here we report an archival search of infrared data for possible Earth Trojans, producing the candidate 2010 TK(7). We subsequently made optical observations which established that 2010 TK(7) is a Trojan companion of Earth, librating around the leading Lagrange triangular point, L(4). Its orbit is stable over at least ten thousand years. PMID:21796207

  8. How Big is Earth?

    NASA Astrophysics Data System (ADS)

    Thurber, Bonnie B.

    2015-08-01

    How Big is Earth celebrates the Year of Light. Using only the sunlight striking the Earth and a wooden dowel, students meet each other and then measure the circumference of the earth. Eratosthenes did it over 2,000 years ago. In Cosmos, Carl Sagan shared the process by which Eratosthenes measured the angle of the shadow cast at local noon when sunlight strikes a stick positioned perpendicular to the ground. By comparing his measurement to another made a distance away, Eratosthenes was able to calculate the circumference of the earth. How Big is Earth provides an online learning environment where students do science the same way Eratosthenes did. A notable project in which this was done was The Eratosthenes Project, conducted in 2005 as part of the World Year of Physics; in fact, we will be drawing on the teacher's guide developed by that project.How Big Is Earth? expands on the Eratosthenes project by providing an online learning environment provided by the iCollaboratory, www.icollaboratory.org, where teachers and students from Sweden, China, Nepal, Russia, Morocco, and the United States collaborate, share data, and reflect on their learning of science and astronomy. They are sharing their information and discussing their ideas/brainstorming the solutions in a discussion forum. There is an ongoing database of student measurements and another database to collect data on both teacher and student learning from surveys, discussions, and self-reflection done online.We will share our research about the kinds of learning that takes place only in global collaborations.The entrance address for the iCollaboratory is http://www.icollaboratory.org.

  9. Google Earth Engine

    NASA Astrophysics Data System (ADS)

    Gorelick, N.

    2012-12-01

    The Google Earth Engine platform is a system designed to enable petabyte-scale, scientific analysis and visualization of geospatial datasets. Earth Engine provides a consolidated environment including a massive data catalog co-located with thousands of computers for analysis. The user-friendly front-end provides a workbench environment to allow interactive data and algorithm development and exploration and provides a convenient mechanism for scientists to share data, visualizations and analytic algorithms via URLs. The Earth Engine data catalog contains a wide variety of popular, curated datasets, including the world's largest online collection of Landsat scenes (> 2.0M), numerous MODIS collections, and many vector-based data sets. The platform provides a uniform access mechanism to a variety of data types, independent of their bands, projection, bit-depth, resolution, etc..., facilitating easy multi-sensor analysis. Additionally, a user is able to add and curate their own data and collections. Using a just-in-time, distributed computation model, Earth Engine can rapidly process enormous quantities of geo-spatial data. All computation is performed lazily; nothing is computed until it's required either for output or as input to another step. This model allows real-time feedback and preview during algorithm development, supporting a rapid algorithm development, test, and improvement cycle that scales seamlessly to large-scale production data processing. Through integration with a variety of other services, Earth Engine is able to bring to bear considerable analytic and technical firepower in a transparent fashion, including: AI-based classification via integration with Google's machine learning infrastructure, publishing and distribution at Google scale through integration with the Google Maps API, Maps Engine and Google Earth, and support for in-the-field activities such as validation, ground-truthing, crowd-sourcing and citizen science though the Android Open Data

  10. Google Earth Engine

    NASA Astrophysics Data System (ADS)

    Gorelick, Noel

    2013-04-01

    The Google Earth Engine platform is a system designed to enable petabyte-scale, scientific analysis and visualization of geospatial datasets. Earth Engine provides a consolidated environment including a massive data catalog co-located with thousands of computers for analysis. The user-friendly front-end provides a workbench environment to allow interactive data and algorithm development and exploration and provides a convenient mechanism for scientists to share data, visualizations and analytic algorithms via URLs. The Earth Engine data catalog contains a wide variety of popular, curated datasets, including the world's largest online collection of Landsat scenes (> 2.0M), numerous MODIS collections, and many vector-based data sets. The platform provides a uniform access mechanism to a variety of data types, independent of their bands, projection, bit-depth, resolution, etc..., facilitating easy multi-sensor analysis. Additionally, a user is able to add and curate their own data and collections. Using a just-in-time, distributed computation model, Earth Engine can rapidly process enormous quantities of geo-spatial data. All computation is performed lazily; nothing is computed until it's required either for output or as input to another step. This model allows real-time feedback and preview during algorithm development, supporting a rapid algorithm development, test, and improvement cycle that scales seamlessly to large-scale production data processing. Through integration with a variety of other services, Earth Engine is able to bring to bear considerable analytic and technical firepower in a transparent fashion, including: AI-based classification via integration with Google's machine learning infrastructure, publishing and distribution at Google scale through integration with the Google Maps API, Maps Engine and Google Earth, and support for in-the-field activities such as validation, ground-truthing, crowd-sourcing and citizen science though the Android Open Data

  11. Teaching earth science

    USGS Publications Warehouse

    Alpha, Tau Rho, (Edited By); Diggles, M.F.

    1998-01-01

    This CD-ROM contains 17 teaching tools: 16 interactive HyperCard 'stacks' and a printable model. They are separated into the following categories: Geologic Processes, Earthquakes and Faulting, and Map Projections and Globes. A 'navigation' stack, Earth Science, is provided as a 'launching' place from which to access all of the other stacks. You can also open the HyperCard Stacks folder and launch any of the 16 stacks yourself. In addition, a 17th tool, Earth and Tectonic Globes, is provided as a printable document. Each of the tools can be copied onto a 1.4-MB floppy disk and distributed freely.

  12. Blowing up the Earth

    NASA Astrophysics Data System (ADS)

    Benge, Raymond

    2006-10-01

    An occasional theme in science fiction involves blowing up a planet. In ``Star Wars,'' the Death Star blows up Alderan. In ``The Hitchhiker's Guide to the Galaxy,'' a Vorgon destructor fleet blows up Earth to make room for a cosmic bypass. So, as an exercise for upper division students, or the more advance first year calculus based physics students, the energy needed to disassemble Earth can be computed. Assuming that advanced scifi aliens get their energy from matter-antimatter interactions, students can then compute the amount of antimatter needed to accomplish the task.

  13. The wooing of earth

    SciTech Connect

    Dubos, R.

    1981-02-01

    Reckless use of energy by industrial nations has begun to alter the global climate. Each year more arable land is lost to desertification and erosion due to anthropogenic activities. Air pollutants carried by winds contaminate ecosystems in many parts of the globe. Various kinds of wilderness are being spoiled by overexploitation or permanent occupation. However, human interventions into nature have often revealed potentialities of the earth that would have remained unexpressed in the state of wilderness. With knowledge and a sense of responsibility for the welfare of the earth, human intervention into nature can be ecologically sound, aesthetically satisfying, and economically rewarding.

  14. Magnetic susceptibility and low-temperature structure of the linear chain cuprate Sr2CuO3

    NASA Astrophysics Data System (ADS)

    Ami, T.; Crawford, M. K.; Harlow, R. L.; Wang, Z. R.; Johnston, D. C.; Huang, Q.; Erwin, R. W.

    1995-03-01

    Magnetic susceptibility measurements for Sr2CuO3+/-δ were made from 2 to 800 K, and a strong dependence upon oxygen content (δ) was observed. Samples synthesized under oxygen, followed by various nitrogen treatments, exhibited markedly different Curie-Weiss-type terms, and we discuss possible origins for this behavior. High-temperature magnetic susceptibility measurements for the sample with the smallest Curie-Weiss-type term clearly show the increase with temperature expected from the Bonner-Fisher model for a spin-1/2 one-dimensional (1D) Heisenberg antiferromagnet. This is a direct experimental observation of 1D magnetic behavior in this system. The in-chain superexchange coupling constant, as determined by a fit to the Bonner-Fisher model, is ||J||/kB~=1300+100-200 K, comparable to the values observed in the two-dimensional layered cuprates. Estimates of the interchain magnetic interaction indicate this material may be the best realization of a 1D spin-1/2 Heisenberg antiferromagnet reported to date. Low-temperature neutron and synchrotron x-ray powder-diffraction studies of Sr2CuO3 show that the low-temperature structure of this system has Immm space-group symmetry, the same structure reported at room temperature, indicating that this material, in contrast to La2CuO4, does not undergo any structural transformations upon cooling. The absence of crystallographic distortions precludes a magnetic anisotropy contribution from a Dzyaloshinsky-Moriya interaction, implying that Sr2CuO3 should be a nearly ideal spin-1/2 antiferromagnetic Heisenberg chain compound, in agreement with the magnetic susceptibility results. A search for the presence of long-range three-dimensional antiferromagnetic order by magnetic neutron powder diffraction at temperatures as low as 1.5 K was not successful, although we estimate an upper limit for the size of the ordered moment which could have been detected to be ~0.1μB per Cu2+ ion.

  15. The Earth's Plamasphere

    NASA Technical Reports Server (NTRS)

    Gallagher, D. L.

    2015-01-01

    The Earth's plasmasphere is an inner part of the magneteosphere. It is located just outside the upper ionosphere located in Earth's atmosphere. It is a region of dense, cold plasma that surrounds the Earth. Although plasma is found throughout the magnetosphere, the plasmasphere usually contains the coldest plasma. Here's how it works: The upper reaches of our planet's atmosphere are exposed to ultraviolet light from the Sun, and they are ionized with electrons that are freed from neutral atmospheric particles. The results are electrically charged negative and positive particles. The negative particles are electrons, and the positive particles are now called ions (formerly atoms and molecules). If the density of these particles is low enough, this electrically charged gas behaves differently than it would if it were neutral. Now this gas is called plasma. The atmospheric gas density becomes low enough to support the conditions for a plasma around earth at about 90 kilometers above Earth's surface. The electrons in plasma gain more energy, and they are very low in mass. They move along Earth's magnetic field lines and their increased energy is enough to escape Earth's gravity. Because electrons are very light, they don't have to gain too much kinetic energy from the Sun's ultraviolet light before gravity loses its grip on them. Gravity is not all that holds them back, however. As more and more electrons begin to escape outward, they leave behind a growing net positive electric charge in the ionosphere and create a growing net negative electric charge above the ionosphere; an electric field begins to develop (the Pannekoek-Rosseland E-field). Thus, these different interacting charges result in a positively charged ionosphere and negatively charged region of space above it. Very quickly this resulting electric field opposed upward movement of the electrons out of the ionosphere. The electrons still have this increased energy, however, so the electric field doesn't just

  16. Earth Sciences Division

    NASA Astrophysics Data System (ADS)

    1991-06-01

    This Annual Report presents summaries of selected representative research activities grouped according to the principal disciplines of the Earth Sciences Division: Reservoir Engineering and Hydrogeology, Geology and Geochemistry, and Geophysics and Geomechanics. Much of the Division's research deals with the physical and chemical properties and processes in the earth's crust, from the partially saturated, low-temperature near-surface environment to the high-temperature environments characteristic of regions where magmatic-hydrothermal processes are active. Strengths in laboratory and field instrumentation, numerical modeling, and in situ measurement allow study of the transport of mass and heat through geologic media -- studies that now include the appropriate chemical reactions and the hydraulic-mechanical complexities of fractured rock systems. Of particular note are three major Division efforts addressing problems in the discovery and recovery of petroleum, the application of isotope geochemistry to the study of geodynamic processes and earth history, and the development of borehole methods for high-resolution imaging of the subsurface using seismic and electromagnetic waves. In 1989, a major DOE-wide effort was launched in the areas of Environmental Restoration and Waste Management. Many of the methods previously developed for and applied to deeper regions of the earth will, in the coming years, be turned toward process definition and characterization of the very shallow subsurface, where man-induced contaminants now intrude and where remedial action is required.

  17. "Galileo Calling Earth..."

    ERIC Educational Resources Information Center

    National Aeronautics and Space Administration, Washington, DC.

    This guide presents an activity for helping students understand how data from the Galileo spacecraft is sent to scientists on earth. Students are asked to learn about the concepts of bit-rate and resolution and apply them to the interpretation of images from the Galileo Orbiter. (WRM)

  18. The earth's magnetosphere

    NASA Technical Reports Server (NTRS)

    Coroniti, F. V.

    1976-01-01

    The following aspects of the earth's magnetosphere were discussed: general structure, magnetic field merging and magnetospheric convection, time-varying convection and magnetospheric substorms, magnetic storms, and comparative magnetospheres. Solar flares and the magnetospheres of Mercury, Venus, Mars, Jupiter, Saturn, and Uranus were also described.

  19. How life shaped Earth.

    PubMed

    Gross, Michael

    2015-10-01

    Earth is much more complex than all the other solar system objects that we know. Thanks to its rich and diverse geology, our planet can offer habitats to a wide range of living species. Emerging insights suggest that this is not just a happy coincidence, but that life itself has in many ways helped to shape the planet. PMID:26726334

  20. Meteorology: Project Earth Science.

    ERIC Educational Resources Information Center

    Smith, P. Sean; Ford, Brent A.

    This document on meteorology is one of a four-volume series of Project Earth Science that includes exemplary hands-on science and reading materials for use in the classroom. This book is divided into three sections: activities, readings, and appendix. The activities are constructed around three basic concept divisions. First, students investigate…

  1. Trees for Mother Earth.

    ERIC Educational Resources Information Center

    Greer, Sandy

    1993-01-01

    Describes Trees for Mother Earth, a program in which secondary students raise funds to buy fruit trees to plant during visits to the Navajo Reservation. Benefits include developing feelings of self-worth among participants, promoting cultural exchange and understanding, and encouraging self-sufficiency among the Navajo. (LP)

  2. The Earth's Mantle.

    ERIC Educational Resources Information Center

    McKenzie, D. P.

    1983-01-01

    The nature and dynamics of the earth's mantle is discussed. Research indicates that the silicate mantle is heated by the decay of radioactive isotopes and that the heat energizes massive convention currents in the upper 700 kilometers of the ductile rock. These currents and their consequences are considered. (JN)

  3. Earth View, Art View

    ERIC Educational Resources Information Center

    Dambekalns, Lydia

    2005-01-01

    Educational practice today encourages interdisciplinary teaching as teachers address important basic themes from a variety of angles. In this article, the author talks about one of her successful projects that focuses on "sense of place" as one such theme, with the more specific charge of viewing Earth from both scientific and artistic…

  4. Earth Science in 1970

    ERIC Educational Resources Information Center

    Geotimes, 1971

    1971-01-01

    Reviews advancements in earth science during 1970 in each of these areas: economic geology (fuels), economic geology (metals), economic geology (nonmetals), environmental geology, geochemistry, manpower, hydrology, mapping, marine geology, mineralogy, paleontology, plate tectonics, politics and geology, remote sensing, and seismology. (PR)

  5. Earth as art 4

    USGS Publications Warehouse

    U.S. Geologic Survey

    2016-01-01

    Landsat 8 is the latest addition to the long-running series of Earth-observing satellites in the Landsat program that began in 1972. The images featured in this fourth installment of the Earth As Art collection were all acquired by Landsat 8. They show our planet’s diverse landscapes with remarkable clarity.Landsat satellites see the Earth as no human can. Not only do they acquire images from the vantage point of space, but their sensors record infrared as well as visible wavelengths of light. The resulting images often reveal “hidden” details of the Earth’s land surface, making them invaluable for scientific research.As with previous Earth As Art exhibits, these Landsat images were selected solely for their aesthetic appeal. Many of the images have been manipulated to enhance color variations or details. They are not intended for scientific interpretation—only for your viewing pleasure. What do you see in these unique glimpses of the Earth’s continents, islands, and coastlines?

  6. Earth Science Misconceptions.

    ERIC Educational Resources Information Center

    Philips, William C.

    1991-01-01

    Presented is a list of over 50 commonly held misconceptions based on a literature review found in students and adults. The list covers earth science topics such as space, the lithosphere, the biosphere, the atmosphere, the hydrosphere, and the cryosphere. (KR)

  7. Exploring the Earth's Past

    ERIC Educational Resources Information Center

    Lindaman, Arnold D.; And Others

    1972-01-01

    Describes three approaches to a study of the earth's past: (1) development of a time line of the ages; (2) a study of rocks and how each was formed; and (3) a study of fossils as found in certain kinds of stone. (Editor)

  8. Earth flyby anomalies

    SciTech Connect

    Nieto, Michael Martin; Anderson, John D

    2009-01-01

    In the planet-centric system, a spacecraft should have the same initial and final energies, even though its energy and angular momentum will change in the barycenter of the solar system. However, without explanation, a number of earth flybys have yielded small energy changes.

  9. Earth System science

    NASA Technical Reports Server (NTRS)

    Prinn, R. G.

    1992-01-01

    Recent research has solidified a view of the Earth as a global-scale interactive system with complex chemical, physical, biological and dynamical processes that link the ocean, atmosphere, land (soils, ice, snow) and marine and terrestrial living organisms. These processes both within and between the major parts of the system help determine global and regional climate and control the biogeochemical and hydrologic cycles essential to life. The study of the Earth System requires measurements ranging from the scales of the smallest processes to the global scale. An ambitious satellite observational program, the Earth Observing System (EOS), carried out along with the complementary and ongoing World Climate Research Program (WCRP) and International Geosphere-Biosphere Program (IGBP) represents a major international effort to understand this System and predict its future changes. The complex and intriguing nature of the Earth System is discussed along with a number of closely coupled processes occurring within it. These are: clouds, precipitation and vegetation; ocean circulation, sea-surface temperature and phytoplankton; coupled oceanic and atmospheric circulation (the Southern Oscillation); biological activity, atmospheric chemistry and climate; and biological emissions and the ozone layer.

  10. Earth's Reflection: Albedo

    ERIC Educational Resources Information Center

    Gillette, Brandon; Hamilton, Cheri

    2011-01-01

    When viewing objects of different colors, you might notice that some appear brighter than others. This is because light is reflected differently from various surfaces, depending on their physical properties. The word "albedo" is used to describe how reflective a surface is. The Earth-atmosphere has a combined albedo of about 30%, a number that is…

  11. Mission: New Earth.

    ERIC Educational Resources Information Center

    Sparks, David

    1997-01-01

    Describes an interdisciplinary unit on the environment and space travel in which students plan a fictional departure from Earth which is on the brink of destruction from environmental waste and neglect. Students travel through concepts in environmental education, math, art, English, and astronomy before reaching their destination with a clearer…

  12. Geology: The Active Earth.

    ERIC Educational Resources Information Center

    Braus, Judy, Ed.

    1987-01-01

    Ranger Rick's NatureScope is a creative education series dedicated to inspiring in children an understanding and appreciation of the natural world while developing the skills they will need to make responsible decisions about the environment. The topic of this issue is "Geology: The Active Earth." Contents are organized into the following…

  13. Rates of Earth degassing

    NASA Technical Reports Server (NTRS)

    Onions, R. K.

    1994-01-01

    The degassing of the Earth during accretion is constrained by Pu-U-I-Xe systematics. Degassing was much more efficient during the first 100-200 Ma than subsequently, and it was more complete for Xe than for the lighter gases. More than 90 percent of the degassed Xe escaped from the atmosphere during this period. The combination of fractional degassing of melts and rare gas escape from the atmosphere is able to explain the deficit of terrestrial Xe as a simple consequence of this early degassing history. By the time Xe was quantitatively retained in the atmosphere, the abundances of Kr and the lighter gases in the Earth's interior were similar to or higher than the present-day atmospheric abundances. Subsequent transfer of these lighter rare gases into the atmosphere requires a high rate of post-accretion degassing and melt production. Considerations of Pu-U-Xe systematics suggest that relatively rapid post-accretion degassing was continued to ca. 4.1-4.2 Ga. The present-day degassing history of the Earth is investigated through consideration of rare gas isotope abundances. Although the Earth is a highly degassed body, depleted in rare gases by many orders of magnitude relative to their solar abundances, it is at the present-day losing primordial rare gases which were trapped at the time of accretion.

  14. Modeling Earth's Climate

    ERIC Educational Resources Information Center

    Pallant, Amy; Lee, Hee-Sun; Pryputniewicz, Sara

    2012-01-01

    Systems thinking suggests that one can best understand a complex system by studying the interrelationships of its component parts rather than looking at the individual parts in isolation. With ongoing concern about the effects of climate change, using innovative materials to help students understand how Earth's systems connect with each other is…

  15. Earth's magnetic environment

    SciTech Connect

    Lanzerotti, L.J.; Uberoi, C.

    1988-10-01

    The nature of the earth's magnetosphere is outlined. The magnetosphere is illustrated and its regions and features are discussed, including solar wind, bow shock, and the magnetopause. The formation process and characteristics of the magnetotail are presented. The plasmasphere, Van Allen belts, auroras, whistlers, and micropulsations are examined. Effects of the magnetosphere, including problems for communications lines, spacecraft electronics, and communication satellites are considered.

  16. Understanding Earth's Albedo Effect

    ERIC Educational Resources Information Center

    Fidler, Chuck

    2012-01-01

    Earth and space science in the middle school classroom are composed of intricately intertwined sets of conceptual systems (AAAS 1993; NRC 1996). Some systems of study, such as the water and rock cycles, are quite explicit and often found as stand-alone middle school science units. Other phenomena are not so apparent, yet they play an extremely…

  17. Earth's City Lights

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This image of Earth's city lights was created with data from the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS). Originally designed to view clouds by moonlight, the OLS is also used to map the locations of permanent lights on the Earth's surface. The brightest areas of the Earth are the most urbanized, but not necessarily the most populated. (Compare western Europe with China and India.) Cities tend to grow along coastlines and transportation networks. Even without the underlying map, the outlines of many continents would still be visible. The United States interstate highway system appears as a lattice connecting the brighter dots of city centers. In Russia, the Trans-Siberian railroad is a thin line stretching from Moscow through the center of Asia to Vladivostok. The Nile River, from the Aswan Dam to the Mediterranean Sea, is another bright thread through an otherwise dark region. Even more than 100 years after the invention of the electric light, some regions remain thinly populated and unlit. Antarctica is entirely dark. The interior jungles of Africa and South America are mostly dark, but lights are beginning to appear there. Deserts in Africa, Arabia, Australia, Mongolia, and the United States are poorly lit as well (except along the coast), along with the boreal forests of Canada and Russia, and the great mountains of the Himalaya. The Earth Observatory article Bright Lights, Big City describes how NASA scientists use city light data to map urbanization. Image by Craig Mayhew and Robert Simmon, NASA GSFC, based on DMSP data

  18. Beyond Earth's Boundaries

    ERIC Educational Resources Information Center

    National Aeronautics and Space Administration, Kennedy Space Center, FL. John F. Kennedy Space Center.

    This resource for teachers of elementary age students provides a foundation for building a life-long interest in the U.S. space program. It begins with a basic understanding of man's attempt to conquer the air, then moves on to how we expanded into near-Earth space for our benefit. Students learn, through hands-on experiences, from projects…

  19. An Earth Day Reader.

    ERIC Educational Resources Information Center

    Moser, Don, Ed.

    1990-01-01

    Presents what the author believes to be some of the most important environmental books published since Earth Day 1970. Discusses each selection and how it provides the historical background, basic information, and appreciation necessary to understand the character of our environmental dilemma and our need to address it. (MCO)

  20. Sun-Earth Day

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Michael Sandras, a member of the Pontchartrain Astronomical Society, explains his solar telescope to students of Second Street in Bay St. Louis, Hancock County and Nicholson elementary schools in StenniSphere's Millennium Hall on April 10. The students participated in several hands-on activities at Stennis Space Center's Sun-Earth Day celebration.