The National Clean Plant Network for Berries in Corvallis
Technology Transfer Automated Retrieval System (TEKTRAN)
The clean plant program at the USDA-ARS in Corvallis, Oregon was initiated in 1967 in cooperation with the Oregon and Washington State Departments of Agriculture and berry growers in the region. The program officially became part of the National Clean Plant Network (NCPN) in 2009 with the establish...
The Agricultural Model Intercomparison and Improvement Project (AgMIP) Town Hall
NASA Technical Reports Server (NTRS)
Ruane, Alex; Rosenzweig, Cynthia; Kyle, Page; Basso, Bruno; Winter, Jonathan; Asseng, Senthold
2015-01-01
AgMIP (www.agmip.org) is an international community of climate, crop, livestock, economics, and IT experts working to further the development and application of multi-model, multi-scale, multi-disciplinary agricultural models that can inform policy and decision makers around the world. This meeting will engage the AGU community by providing a brief overview of AgMIP, in particular its new plans for a Coordinated Global and Regional Assessment of climate change impacts on agriculture and food security for AR6. This Town Hall will help identify opportunities for participants to become involved in AgMIP and its 30+ activities.
Public lands within the Urban Growth Boundary of Corvallis, Oregon contain a diverse population of about 440,000 trees that include over 300 varieties and have an estimated tree cover of 31%. While often unrecognized, urban trees provide a variety of “ecosystem services” or dire...
NASA Astrophysics Data System (ADS)
Read, Nicholas
2015-03-01
Viscosity is a transport coefficient relating to transport of momentum, and usually thought of as the analog of friction that occurs in fluids and solids. More formally, it is the response of the stress to the gradients of the fluid velocity field, or to the rate of change of strain (derivatives of displacement from a reference state). In general, viscosity is described by a fourth-rank tensor. Invoking rotation invariance, it reduces to familiar shear and bulk viscosity parts, which describe dissipation, but it can also contain an antisymmetric part, analogous to the Hall conductivity part of the conductivity tensor. In two dimensions this part is a single number, the Hall viscosity. Symmetry of the system under time reversal (or, in two dimensions, reflections) forces it to vanish. In quantum fluids with a gap in the bulk energy spectrum and which lack both time reversal and reflection symmetries the Hall viscosity can be nonzero even at zero temperature. For integer quantum Hall states, it was first calculated by Avron, Seiler, and Zograf, using a Berry curvature approach, analogous to the Chern number for Hall conductivity. In 2008 this was extended by the present author to fractional quantum Hall states and to BCS states in two dimensions. I found that the general result is given by a simple formula ns / 2 , where n is the particle number density, and s is the ``orbital spin'' per particle. The spin s is also related to the shift S, which enters the relation between particle number and magnetic flux needed to put the ground state on a surface of non-trivial topology with introducing defect excitations, by S = 2 s ; the connection was made by Wen and Zee. The values of s and S are rational numbers, and are robust--unchanged under perturbations that do not cause the bulk energy gap to collapse--provided rotation as well as translation symmetry are maintained. Hall viscosity can be measured in principle, though a simple way to do so is lacking. It enters various
Jungwirth, Tomas; Wunderlich, Jörg; Olejník, Kamil
2012-05-01
The spin Hall effect is a relativistic spin-orbit coupling phenomenon that can be used to electrically generate or detect spin currents in non-magnetic systems. Here we review the experimental results that, since the first experimental observation of the spin Hall effect less than 10 years ago, have established the basic physical understanding of the phenomenon, and the role that several of the spin Hall devices have had in the demonstration of spintronic functionalities and physical phenomena. We have attempted to organize the experiments in a chronological order, while simultaneously dividing the Review into sections on semiconductor or metal spin Hall devices, and on optical or electrical spin Hall experiments. The spin Hall device studies are placed in a broader context of the field of spin injection, manipulation, and detection in non-magnetic conductors.
Bernevig, B Andrei; Zhang, Shou-Cheng
2006-03-17
The quantum Hall liquid is a novel state of matter with profound emergent properties such as fractional charge and statistics. The existence of the quantum Hall effect requires breaking of the time reversal symmetry caused by an external magnetic field. In this work, we predict a quantized spin Hall effect in the absence of any magnetic field, where the intrinsic spin Hall conductance is quantized in units of 2(e/4pi). The degenerate quantum Landau levels are created by the spin-orbit coupling in conventional semiconductors in the presence of a strain gradient. This new state of matter has many profound correlated properties described by a topological field theory.
Bernevig, B.Andrei; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.
2010-01-15
The quantum Hall liquid is a novel state of matter with profound emergent properties such as fractional charge and statistics. Existence of the quantum Hall effect requires breaking of the time reversal symmetry caused by an external magnetic field. In this work, we predict a quantized spin Hall effect in the absence of any magnetic field, where the intrinsic spin Hall conductance is quantized in units of 2 e/4{pi}. The degenerate quantum Landau levels are created by the spin-orbit coupling in conventional semiconductors in the presence of a strain gradient. This new state of matter has many profound correlated properties described by a topological field theory.
ERIC Educational Resources Information Center
El Rancho Unified School District, Pico Rivera, CA.
A Hall of Fame was established by the El Rancho Unified School District (California) to identify and honor graduates of the school district who have graduated more than 15 years ago, who have achieved recognition in their chosen field, and who would bring honor to the school district in its honoring of them. Nominees for the Hall of Fame were…
NASA Technical Reports Server (NTRS)
1985-01-01
The experimental procedure consists of the measurement of the Hall coefficient, resistivity, and Hall mobility as a function of temperature of a sample of gallium arsenides before and after irradiation with low and high energy protons. Work has begun on the development of the theory and subsequently experiments will be designed and performed.
Kim, Bom Soo; Shapere, Alfred D
2016-09-01
We derive a generalized set of Ward identities that captures the effects of topological charge on Hall transport. The Ward identities follow from the (2+1)-dimensional momentum algebra, which includes a central extension proportional to the topological charge density. In the presence of topological objects like Skyrmions, we observe that the central term leads to a direct relation between the thermal Hall conductivity and the topological charge density. We extend this relation to incorporate the effects of a magnetic field and an electric current. The topological charge density produces a distinct signature in the electric Hall conductivity, which is identified in existing experimental data and yields further novel predictions. For insulating materials with translation invariance, the Hall viscosity can be directly determined from the Skyrmion density and the thermal Hall conductivity to be measured as a function of momentum. PMID:27661713
NASA Technical Reports Server (NTRS)
Hruby, Vladimir J. (Inventor); Pote, Bruce M. (Inventor); Gamero-Castano, Manuel (Inventor)
2004-01-01
A pulsed Hall thruster system includes a Hall thruster having an electron source, a magnetic circuit, and a discharge chamber; a power processing unit for firing the Hall thruster to generate a discharge; a propellant storage and delivery system for providing propellant to the discharge chamber and a control unit for defining a pulse duration .tau.<0.1d.sup.3.rho./m, where d is the characteristic size of the thruster, .rho. is the propellant density at standard conditions, and m is the propellant mass flow rate for operating either the power processing unit to provide to the Hall thruster a power pulse of a pre-selected duration, .tau., or operating the propellant storage and delivery system to provide a propellant flow pulse of duration, .tau., or providing both as pulses, synchronized to arrive coincidentally at the discharge chamber to enable the Hall thruster to produce a discreet output impulse.
Facility Focus: Residence Halls.
ERIC Educational Resources Information Center
College Planning & Management, 1999
1999-01-01
Describes four college residence halls that have successfully combined a comfortable, aesthetically pleasing, and socially stimulating atmosphere for its residents. Photographs and interior-design line drawings are included. (GR)
Hall viscosity of hierarchical quantum Hall states
NASA Astrophysics Data System (ADS)
Fremling, Mikael; Hansson, Thors Hans; Suorsa, Juha
2015-03-01
We construct model wave functions on a torus for all chiral states in the abelian quantum Hall hierarchy. These functions have no variational parameters, and they transform under the modular group in the same way as the multicomponent generalizations of the Laughlin wave functions. Assuming the absence of Berry phases upon adiabatic variations of the modular parameter τ, we calculate the quantum Hall viscosity and find it to be in agreement with the formula, given by Read, which relates the viscosity to the average orbital spin of the electrons. For the filling factor ν = 2 / 5 Jain state, which is at the second level in the hierarchy, we compare our model wave function with the numerically obtained ground state of the Coulomb interaction Hamiltonian in the lowest Landau level, and find very good agreement in a large region of the complex τ-plane. For the same example, we also numerically compute the Hall viscosity and find good agreement with the analytical result for both the model wave function and the numerically obtained Coulomb wave function. We argue that this supports the notion of a generalized plasma analogy that would ensure that wave functions obtained using conformal field theory methods do not acquire Berry phases upon adiabatic evolution.
Nonlocal Anomalous Hall Effect
NASA Astrophysics Data System (ADS)
Zhang, Steven S.-L.; Vignale, Giovanni
2016-04-01
The anomalous Hall (AH) effect is deemed to be a unique transport property of ferromagnetic metals, caused by the concerted action of spin polarization and spin-orbit coupling. Nevertheless, recent experiments have shown that the effect also occurs in a nonmagnetic metal (Pt) in contact with a magnetic insulator [yttrium iron garnet (YIG)], even when precautions are taken to ensure that there is no induced magnetization in the metal. We propose a theory of this effect based on the combined action of spin-dependent scattering from the magnetic interface and the spin-Hall effect in the bulk of the metal. At variance with previous theories, we predict the effect to be of first order in the spin-orbit coupling, just as the conventional anomalous Hall effect—the only difference being the spatial separation of the spin-orbit interaction and the magnetization. For this reason we name this effect the nonlocal anomalous Hall effect and predict that its sign will be determined by the sign of the spin-Hall angle in the metal. The AH conductivity that we calculate from our theory is in order of magnitude agreement with the measured values in Pt /YIG structures.
NASA Technical Reports Server (NTRS)
Jankovsky, Robert S.; Jacobson, David T.; Rawlin, Vincent K.; Mason, Lee S.; Mantenieks, Maris A.; Manzella, David H.; Hofer, Richard R.; Peterson, Peter Y.
2001-01-01
NASA's Hall thruster program has base research and focused development efforts in support of the Advanced Space Transportation Program, Space-Based Program, and various other programs. The objective of the base research is to gain an improved understanding of the physical processes and engineering constraints of Hall thrusters to enable development of advanced Hall thruster designs. Specific technical questions that are current priorities of the base effort are: (1) How does thruster life vary with operating point? (2) How can thruster lifetime and wear rate be most efficiently evaluated? (3) What are the practical limitations for discharge voltage as it pertains to high specific impulse operation (high discharge voltage) and high thrust operation (low discharge voltage)? (4) What are the practical limits for extending Hall thrusters to very high input powers? and (5) What can be done during thruster design to reduce cost and integration concerns? The objective of the focused development effort is to develop a 50 kW-class Hall propulsion system, with a milestone of a 50 kW engineering model thruster/system by the end of program year 2006. Specific program wear 2001 efforts, along with the corporate and academic participation, are described.
Nonlocal Anomalous Hall Effect.
Zhang, Steven S-L; Vignale, Giovanni
2016-04-01
The anomalous Hall (AH) effect is deemed to be a unique transport property of ferromagnetic metals, caused by the concerted action of spin polarization and spin-orbit coupling. Nevertheless, recent experiments have shown that the effect also occurs in a nonmagnetic metal (Pt) in contact with a magnetic insulator [yttrium iron garnet (YIG)], even when precautions are taken to ensure that there is no induced magnetization in the metal. We propose a theory of this effect based on the combined action of spin-dependent scattering from the magnetic interface and the spin-Hall effect in the bulk of the metal. At variance with previous theories, we predict the effect to be of first order in the spin-orbit coupling, just as the conventional anomalous Hall effect-the only difference being the spatial separation of the spin-orbit interaction and the magnetization. For this reason we name this effect the nonlocal anomalous Hall effect and predict that its sign will be determined by the sign of the spin-Hall angle in the metal. The AH conductivity that we calculate from our theory is in order of magnitude agreement with the measured values in Pt/YIG structures.
Malyshkin, Leonid M.
2008-11-28
The rate of quasistationary, two-dimensional magnetic reconnection is calculated in the framework of incompressible Hall magnetohydrodynamics, which includes the Hall and electron pressure terms in Ohm's law. The Hall-magnetohydrodynamics equations are solved in a local region across the reconnection electron layer, including only the upstream region and the layer center. In the case when the ion inertial length d{sub i} is larger than the Sweet-Parker reconnection layer thickness, the dimensionless reconnection rate is found to be independent of the electrical resistivity and equal to d{sub i}/L, where L is the scale length of the external magnetic field in the upstream region outside the electron layer and the ion layer thickness is found to be d{sub i}.
NASA Technical Reports Server (NTRS)
Jankovsky, Robert; Tverdokhlebov, Sergery; Manzella, David
1999-01-01
The development of Hall thrusters with powers ranging from tens of kilowatts to in excess of one hundred kilowatts is considered based on renewed interest in high power. high thrust electric propulsion applications. An approach to develop such thrusters based on previous experience is discussed. It is shown that the previous experimental data taken with thrusters of 10 kW input power and less can be used. Potential mass savings due to the design of high power Hall thrusters are discussed. Both xenon and alternate thruster propellant are considered, as are technological issues that will challenge the design of high power Hall thrusters. Finally, the implications of such a development effort with regard to ground testing and spacecraft intecrati'on issues are discussed.
ERIC Educational Resources Information Center
Kunkel, W. B.
1981-01-01
Describes an apparatus and procedure for conducting an undergraduate laboratory experiment to quantitatively study the Hall effect in a plasma. Includes background information on the Hall effect and rationale for conducting the experiment. (JN)
Villa, L; Guerra, B; Schmoger, S; Fischer, J; Helmuth, R; Zong, Z; García-Fernández, A; Carattoli, A
2015-10-01
A Salmonella enterica serovar Corvallis strain was isolated from a wild bird in Germany. This strain carried the IncA/C2 pRH-1238 plasmid. Complete sequencing of the plasmid was performed, identifying the blaNDM-1, blaCMY-16, fosA3, sul1, sul2, strA, strB, aac(6')-Ib, aadA5, aphA6, tetA(A), mphA, floR, dfrA7, and merA genes, which confer clinically relevant resistance to most of the antimicrobial classes, including β-lactams with carbapenems, fosfomycin, aminoglycosides, co-trimoxazole, tetracyclines, and macrolides. The strain likely originated from the Asiatic region and was transferred to Germany through the Milvus migrans migratory route. PMID:26169417
Nonlocal anomalous Hall effect
NASA Astrophysics Data System (ADS)
Zhang, Shulei; Vignale, Giovanni
Anomalous Hall effect (AHE) is a distinctive transport property of ferromagnetic metals arising from spin orbit coupling (SOC) in concert with spontaneous spin polarization. Nonetheless, recent experiments have shown that the effect also appears in a nonmagnetic metal in contact with a magnetic insulator. The main puzzle lies in the apparent absence of spin polarized electrons in the non-magnetic metal. Here, we theoretically demonstrate that the scattering of electrons from a rough metal-insulator interface is generally spin-dependent, which results in mutual conversion between spin and charge currents flowing in the plane of the layer. It is the current-carrying spin polarized electrons and the spin Hall effect in the bulk of the metal layer that conspire to generate the AH current. This novel AHE differs from the conventional one only in the spatial separation of the SOC and the magnetization, so we name it as nonlocal AHE. In contrast to other previously proposed mechanisms (e.g., spin Hall AHE and magnetic proximity effect (MPE)), the nonlocal AHE appears on the first order of spin Hall angle and does not rely on the induced moments in the metal layer, which make it experimentally detectable by contrasting the AH current directions of two layered structures such as Pt/Cu/YIG and β -Ta/Cu/YIG (with a thin inserted Cu layer to eliminate the MPE). We predict that the directions of the AH currents in these two trilayers would be opposite since the spin Hall angles of Pt and β -Ta are of opposite signs. Work supported by NSF Grants DMR-1406568.
NASA's 2004 Hall Thruster Program
NASA Technical Reports Server (NTRS)
Jacobson, David T.; Manzella, David H.; Hofer, Richard R.; Peterson, Peter Y.
2004-01-01
An overview of NASA's Hall thruster research and development tasks conducted during fiscal year 2004 is presented. These tasks focus on: raising the technology readiness level of high power Hall thrusters, developing a moderate-power/ moderate specific impulse Hall thruster, demonstrating high-power/high specific impulse Hall thruster operation, and addressing the fundamental technical challenges of emerging Hall thruster concepts. Programmatic background information, technical accomplishments and out year plans for each program element performed under the sponsorship of the In-Space Transportation Program, Project Prometheus, and the Energetics Project are provided.
NASA Astrophysics Data System (ADS)
Sinova, Jairo; Valenzuela, Sergio O.; Wunderlich, J.; Back, C. H.; Jungwirth, T.
2015-10-01
Spin Hall effects are a collection of relativistic spin-orbit coupling phenomena in which electrical currents can generate transverse spin currents and vice versa. Despite being observed only a decade ago, these effects are already ubiquitous within spintronics, as standard spin-current generators and detectors. Here the theoretical and experimental results that have established this subfield of spintronics are reviewed. The focus is on the results that have converged to give us the current understanding of the phenomena, which has evolved from a qualitative to a more quantitative measurement of spin currents and their associated spin accumulation. Within the experimental framework, optical-, transport-, and magnetization-dynamics-based measurements are reviewed and linked to both phenomenological and microscopic theories of the effect. Within the theoretical framework, the basic mechanisms in both the extrinsic and intrinsic regimes are reviewed, which are linked to the mechanisms present in their closely related phenomenon in ferromagnets, the anomalous Hall effect. Also reviewed is the connection to the phenomenological treatment based on spin-diffusion equations applicable to certain regimes, as well as the spin-pumping theory of spin generation used in many measurements of the spin Hall angle. A further connection to the spin-current-generating spin Hall effect to the inverse spin galvanic effect is given, in which an electrical current induces a nonequilibrium spin polarization. This effect often accompanies the spin Hall effect since they share common microscopic origins. Both can exhibit the same symmetries when present in structures comprising ferromagnetic and nonmagnetic layers through their induced current-driven spin torques or induced voltages. Although a short chronological overview of the evolution of the spin Hall effect field and the resolution of some early controversies is given, the main body of this review is structured from a pedagogical
Cylindrical geometry hall thruster
Raitses, Yevgeny; Fisch, Nathaniel J.
2002-01-01
An apparatus and method for thrusting plasma, utilizing a Hall thruster with a cylindrical geometry, wherein ions are accelerated in substantially the axial direction. The apparatus is suitable for operation at low power. It employs small size thruster components, including a ceramic channel, with the center pole piece of the conventional annular design thruster eliminated or greatly reduced. Efficient operation is accomplished through magnetic fields with a substantial radial component. The propellant gas is ionized at an optimal location in the thruster. A further improvement is accomplished by segmented electrodes, which produce localized voltage drops within the thruster at optimally prescribed locations. The apparatus differs from a conventional Hall thruster, which has an annular geometry, not well suited to scaling to small size, because the small size for an annular design has a great deal of surface area relative to the volume.
NASA Technical Reports Server (NTRS)
Goebel, Dan Michael (Inventor); Hofer, Richard Robert (Inventor); Mikellides, Ioannis G. (Inventor)
2016-01-01
A Hall thruster apparatus having walls constructed from a conductive material, such as graphite, and having magnetic shielding of the walls from the ionized plasma has been demonstrated to operate with nearly the same efficiency as a conventional non-magnetically shielded design using insulators as wall components. The new design is believed to provide the potential of higher power and uniform operation over the operating life of a thruster device.
NASA Astrophysics Data System (ADS)
Kumar, Akshay
We study several quantum phases that are related to the quantum Hall effect. Our initial focus is on a pair of quantum Hall ferromagnets where the quantum Hall ordering occurs simultaneously with a spontaneous breaking of an internal symmetry associated with a semiconductor valley index. In our first example ---AlAs heterostructures--- we study domain wall structure, role of random-field disorder and dipole moment physics. Then in the second example ---Si(111)--- we show that symmetry breaking near several integer filling fractions involves a combination of selection by thermal fluctuations known as "order by disorder" and a selection by the energetics of Skyrme lattices induced by moving away from the commensurate fillings, a mechanism we term "order by doping". We also study ground state of such systems near filling factor one in the absence of valley Zeeman energy. We show that even though the lowest energy charged excitations are charge one skyrmions, the lowest energy skyrmion lattice has charge > 1 per unit cell. We then broaden our discussion to include lattice systems having multiple Chern number bands. We find analogs of quantum Hall ferromagnets in the menagerie of fractional Chern insulator phases. Unlike in the AlAs system, here the domain walls come naturally with gapped electronic excitations. We close with a result involving only topology: we show that ABC stacked multilayer graphene placed on boron nitride substrate has flat bands with non-zero local Berry curvature but zero Chern number. This allows access to an interaction dominated system with a non-trivial quantum distance metric but without the extra complication of a non-zero Chern number.
27. THIRD FLOOR MAIN HALL FROM SIDE HALL LEADING TO ...
27. THIRD FLOOR MAIN HALL FROM SIDE HALL LEADING TO SERVICE STAIRS This hall is lit by three natural sources, the lightwell window of the main stairs visible in the distance, the skylight in the linen closet at the extreme left, and from the glazed openings in the interior and exterior doors of the nurse's room, out of sight to the right. - Woodrow Wilson House, 2340 South S Street, Northwest, Washington, District of Columbia, DC
NASA Technical Reports Server (NTRS)
Szabo, James J.
2015-01-01
This Phase II project is developing a magnesium (Mg) Hall effect thruster system that would open the door for in situ resource utilization (ISRU)-based solar system exploration. Magnesium is light and easy to ionize. For a Mars- Earth transfer, the propellant mass savings with respect to a xenon Hall effect thruster (HET) system are enormous. Magnesium also can be combusted in a rocket with carbon dioxide (CO2) or water (H2O), enabling a multimode propulsion system with propellant sharing and ISRU. In the near term, CO2 and H2O would be collected in situ on Mars or the moon. In the far term, Mg itself would be collected from Martian and lunar regolith. In Phase I, an integrated, medium-power (1- to 3-kW) Mg HET system was developed and tested. Controlled, steady operation at constant voltage and power was demonstrated. Preliminary measurements indicate a specific impulse (Isp) greater than 4,000 s was achieved at a discharge potential of 400 V. The feasibility of delivering fluidized Mg powder to a medium- or high-power thruster also was demonstrated. Phase II of the project evaluated the performance of an integrated, highpower Mg Hall thruster system in a relevant space environment. Researchers improved the medium power thruster system and characterized it in detail. Researchers also designed and built a high-power (8- to 20-kW) Mg HET. A fluidized powder feed system supporting the high-power thruster was built and delivered to Busek Company, Inc.
NASA Astrophysics Data System (ADS)
Radzihovsky, Leo
2003-03-01
Liquid-crystals, defined as states of matter intermediate in their properties between fully disordered isotropic liquids and fully ordered crystals are ubiquitous in nature. Recent transport measurements on two-dimensional electron systems in moderate magnetic fields suggest the existence of a spontaneously orientationally-ordered, compressible liquid state. I will discuss electronic liquid-crystals interpretation of these experiments, focusing on a recently proposed quantum Hall nematic state that is predicted to exhibit a novel, highly anisotropic q^3 density-director mode and other interesting phenomenology.
Predictors of Residence Hall Involvement
ERIC Educational Resources Information Center
Arboleda, Ana; Wang, Yongyi; Shelley, Mack C., II; Whalen, Donald F.
2003-01-01
Residence hall students' (N = 1,186, 52% male, 90% White, 66% freshmen) involvement in their living community is influenced significantly by precollege student characteristics (gender, ethnicity), classification, attitudes (toward hall director, house cabinet, academic comfort, social environment, group study), and environmental variables (noise,…
Residence Hall Seating That Works.
ERIC Educational Resources Information Center
Wiens, Janet
2003-01-01
Describes the seating chosen for residence halls at the Massachusetts Institute of Technology and the University of New England. The seating required depends on ergonomics, aesthetics, durability, cost, and code requirements. In addition, residence halls must have a range of seating types to accommodate various uses. (SLD)
ERIC Educational Resources Information Center
Strong, Bryan; DeVault, Christine
1994-01-01
Responds to previous article by Stolley and Hall (this issue) on presentation of abortion and adoption in undergraduate marriage and family textbooks. Agrees that adoption should be covered more comprehensively, but disagrees with Stolley and Hall on issue of parity of coverage of adoption and abortion as choices in resolution of unwanted…
NASA's Hall Thruster Program 2002
NASA Technical Reports Server (NTRS)
Jankovsky, Robert S.; Jacobson, David T.; Pinero, Luis R.; Manzella, David H.; Hofer, Richard R.; Peterson, Peter Y.
2002-01-01
The NASA Hall thruster program currently supports a number of tasks related to high power thruster development for a number of customers including the Energetics Program (formerly called the Space-based Program), the Space Solar Power Program, and the In-space Propulsion Program. In program year 2002, two tasks were central to the NASA Hall thruster program: 1) the development of a laboratory Hall thruster capable of providing high thrust at high power-, and 2) investigations into operation of Hall thrusters at high specific impulse. In addition to these two primary thruster development activities, there are a number of other on-going activities supported by the NASA Hall thruster program. These additional activities are related to issues such as high-power power processor architecture, thruster lifetime, and spacecraft integration.
NASA Astrophysics Data System (ADS)
Cassidy, David C.
2013-03-01
It's July 1945. Germany is in defeat and the atomic bombs are on their way to Japan. Under the direction of Samuel Goudsmit, the Allies are holding some of the top German nuclear scientists-among them Heisenberg, Hahn, and Gerlach-captive in Farm Hall, an English country manor near Cambridge, England. As secret microphones record their conversations, the scientists are unaware of why they are being held or for how long. Thinking themselves far ahead of the Allies, how will they react to the news of the atomic bombs? How will these famous scientists explain to themselves and to the world their failure to achieve even a chain reaction? How will they come to terms with the horror of the Third Reich, their work for such a regime, and their behavior during that period? This one-act play is based upon the transcripts of their conversations as well as the author's historical work on the subject.
Hall Effect Gyrators and Circulators
NASA Astrophysics Data System (ADS)
Viola, Giovanni; DiVincenzo, David P.
2014-04-01
The electronic circulator and its close relative the gyrator are invaluable tools for noise management and signal routing in the current generation of low-temperature microwave systems for the implementation of new quantum technologies. The current implementation of these devices using the Faraday effect is satisfactory but requires a bulky structure whose physical dimension is close to the microwave wavelength employed. The Hall effect is an alternative nonreciprocal effect that can also be used to produce desired device functionality. We review earlier efforts to use an Ohmically contacted four-terminal Hall bar, explaining why this approach leads to unacceptably high device loss. We find that capacitive coupling to such a Hall conductor has much greater promise for achieving good circulator and gyrator functionality. We formulate a classical Ohm-Hall analysis for calculating the properties of such a device, and show how this classical theory simplifies remarkably in the limiting case of the Hall angle approaching 90°. In this limit, we find that either a four-terminal or a three-terminal capacitive device can give excellent circulator behavior, with device dimensions far smaller than the ac wavelength. An experiment is proposed to achieve GHz-band gyration in millimeter (and smaller) scale structures employing either semiconductor heterostructure or graphene Hall conductors. An inductively coupled scheme for realizing a Hall gyrator is also analyzed.
Tuning giant anomalous Hall resistance ratio in perpendicular Hall balance
Zhang, J. Y.; Yang, G.; Wang, S. G. E-mail: ghyu@mater.ustb.edu.cn; Liu, J. L.; Wang, R. M.; Amsellem, E.; Kohn, A.; Yu, G. H. E-mail: ghyu@mater.ustb.edu.cn
2015-04-13
Anomalous Hall effect at room temperature in perpendicular Hall balance with a core structure of [Pt/Co]{sub 4}/NiO/[Co/Pt]{sub 4} has been tuned by functional CoO layers, where [Pt/Co]{sub 4} multilayers exhibit perpendicular magnetic anisotropy. A giant Hall resistance ratio up to 69 900% and saturation Hall resistance (R{sub S}{sup P}) up to 2590 mΩ were obtained in CoO/[Pt/Co]{sub 4}/NiO/[Co/Pt]{sub 4}/CoO system, which is 302% and 146% larger than that in the structure without CoO layers, respectively. Transmission electron microscopy shows highly textured [Co/Pt]{sub 4} multilayers and oxide layers with local epitaxial relations, indicating that the crystallographic structure has significant influence on spin dependent transport properties.
Multilayer thin film Hall effect device
NASA Technical Reports Server (NTRS)
Peters, Palmer N. (Inventor); Sisk, R. Charles (Inventor)
1994-01-01
A Hall effect device and a method of obtaining a magnetic field map of a magnetic body with the Hall effect device are presented. The device comprises: (1) a substrate, (2) a first layer having a first Hall coefficient deposited over the substrate, and (3) a second layer having a second Hall coefficient deposited over the first layer, the first and second layers cooperating to create, in the Hall effect device, a third Hall coefficient different from the first and second Hall coefficients. Creation of the third Hall coefficient by cooperation of the first and second layers allows use of materials for the first and second layers that were previously unavailable for Hall effect devices due to their relatively weak Hall coefficient.
Martin Hall Receives Inventors Award
NASA Technical Reports Server (NTRS)
1965-01-01
In this photograph, Marshall Space Flight Center Director, Dr. Wernher von Braun, presents a Co-Inventor's award to MSFC employee Martin Hall of the Mechanical Engineering Laboratory during the NASA Anniversary ceremony.
Optimization of Cylindrical Hall Thrusters
Yevgeny Raitses, Artem Smirnov, Erik Granstedt, and Nathaniel J. Fi
2007-07-24
The cylindrical Hall thruster features high ionization efficiency, quiet operation, and ion acceleration in a large volume-to-surface ratio channel with performance comparable with the state-of-the-art annular Hall thrusters. These characteristics were demonstrated in low and medium power ranges. Optimization of miniaturized cylindrical thrusters led to performance improvements in the 50-200W input power range, including plume narrowing, increased thruster efficiency, reliable discharge initiation, and stable operation. __________________________________________________
Optimization of Cylindrical Hall Thrusters
Yevgeny Raitses, Artem Smirnov, Erik Granstedt, and Nathaniel J. Fisch
2007-11-27
The cylindrical Hall thruster features high ionization efficiency, quiet operation, and ion acceleration in a large volume-to-surface ratio channel with performance comparable with the state-of-the-art annular Hall thrusters. These characteristics were demonstrated in low and medium power ranges. Optimization of miniaturized cylindrical thrusters led to performance improvements in the 50-200W input power range, including plume narrowing, increased thruster efficiency, reliable discharge initiation, and stable operation.
NASA Astrophysics Data System (ADS)
Nagaosa, Naoto; Sinova, Jairo; Onoda, Shigeki; MacDonald, A. H.; Ong, N. P.
2010-04-01
The anomalous Hall effect (AHE) occurs in solids with broken time-reversal symmetry, typically in a ferromagnetic phase, as a consequence of spin-orbit coupling. Experimental and theoretical studies of the AHE are reviewed, focusing on recent developments that have provided a more complete framework for understanding this subtle phenomenon and have, in many instances, replaced controversy by clarity. Synergy between experimental and theoretical works, both playing a crucial role, has been at the heart of these advances. On the theoretical front, the adoption of the Berry-phase concepts has established a link between the AHE and the topological nature of the Hall currents. On the experimental front, new experimental studies of the AHE in transition metals, transition-metal oxides, spinels, pyrochlores, and metallic dilute magnetic semiconductors have established systematic trends. These two developments, in concert with first-principles electronic structure calculations, strongly favor the dominance of an intrinsic Berry-phase-related AHE mechanism in metallic ferromagnets with moderate conductivity. The intrinsic AHE can be expressed in terms of the Berry-phase curvatures and it is therefore an intrinsic quantum-mechanical property of a perfect crystal. An extrinsic mechanism, skew scattering from disorder, tends to dominate the AHE in highly conductive ferromagnets. The full modern semiclassical treatment of the AHE is reviewed which incorporates an anomalous contribution to wave-packet group velocity due to momentum-space Berry curvatures and correctly combines the roles of intrinsic and extrinsic (skew-scattering and side-jump) scattering-related mechanisms. In addition, more rigorous quantum-mechanical treatments based on the Kubo and Keldysh formalisms are reviewed, taking into account multiband effects, and demonstrate the equivalence of all three linear response theories in the metallic regime. Building on results from recent experiment and theory, a
Not your grandfather's concert hall
NASA Astrophysics Data System (ADS)
Cooper, Russell; Malenka, Richard; Griffith, Charles; Friedlander, Steven
2001-05-01
The opening of Judy and Arthur Zankel Hall on 12 September 2003, restores Andrew Carnegie's original 1891 concept of having three outstanding auditoriums of different sizes under one roof, and creates a 21st-century venue for music performance and education. With concerts ranging from early music to avant-garde multimedia productions, from jazz to world music, and from solo recitals to chamber music, Zankel Hall expands the breadth and depth of Carnegie Hall's offerings. It allows for the integration of programming across three halls with minifestivals tailored both to the size and strengths of each hall and to the artists and music to be performed. The new flexible space also provides Carnegie Hall with an education center equipped with advanced communications technology. This paper discusses the unique program planned for this facility and how the architects, theatre consultants, and acousticians developed a design that fulfilled the client's expectations and coordinated the construction of the facility under the floor of the main Isaac Stern Auditorium without having to cancel a single performance.
Bismuth nano-Hall Sensor for Scanning Hall Probe Microscopy
NASA Astrophysics Data System (ADS)
Sonusen, Selda; Dede, Munir; Oral, Ahmet
2013-03-01
Scanning hall probe microscopy (SHPM) is a non invasive and quantitative magnetic imaging technique, which provides high spatial (50nm) and magnetic resolution to image magnetic and superconducting materials. SHPM can also work under high magnetic field and in a wide temperature (range 30mK -300K). Since Bismuth is a semimetal with a concentration five orders of magnitude lower than metals and negligible surface charge depletion effect, it is an alternative material for Hall probes for SHPM. In this work, we fabricated Bi Hall sensors with different sizes ranging from 10nm to 50nm- by electron beam lithography. The sensors are calibrated -under high magnetic fields -and the minimum detectable magnetic field was measured in a broad temperature range, 4-300K. In addition, 50nm Bi Hall sensors are -used for imaging magnetic domains in Iron Garnet thin film crystal. A detailed electrical characterization and performance of the 25nm and 50nm Hall Sensors will also be presented.
NASA Technical Reports Server (NTRS)
Szabo, James
2015-01-01
Iodine enables dramatic mass and cost savings for lunar and Mars cargo missions, including Earth escape and near-Earth space maneuvers. The demonstrated throttling ability of iodine is important for a singular thruster that might be called upon to propel a spacecraft from Earth to Mars or Venus. The ability to throttle efficiently is even more important for missions beyond Mars. In the Phase I project, Busek Company, Inc., tested an existing Hall thruster, the BHT-8000, on iodine propellant. The thruster was fed by a high-flow iodine feed system and supported by an existing Busek hollow cathode flowing xenon gas. The Phase I propellant feed system was evolved from a previously demonstrated laboratory feed system. Throttling of the thruster between 2 and 11 kW at 200 to 600 V was demonstrated. Testing showed that the efficiency of iodine fueled BHT-8000 is the same as with xenon, with iodine delivering a slightly higher thrust-to-power (T/P) ratio. In Phase II, a complete iodine-fueled system was developed, including the thruster, hollow cathode, and iodine propellant feed system. The nominal power of the Phase II system is 8 kW; however, it can be deeply throttled as well as clustered to much higher power levels. The technology also can be scaled to greater than 100 kW per thruster to support megawatt-class missions. The target thruster efficiency for the full-scale system is 65 percent at high specific impulse (Isp) (approximately 3,000 s) and 60 percent at high thrust (Isp approximately 2,000 s).
Spin Hall controlled magnonic microwaveguides
Demidov, V. E.; Urazhdin, S.; Rinkevich, A. B.; Reiss, G.; Demokritov, S. O.
2014-04-14
We use space-resolved magneto-optical spectroscopy to study the influence of spin Hall effect on the excitation and propagation of spin waves in microscopic magnonic waveguides. We find that the spin Hall effect not only increases the spin-wave propagation length, but also results in an increased excitation efficiency due to the increase of the dynamic susceptibility in the vicinity of the inductive antenna. We show that the efficiency of the propagation length enhancement is strongly dependant on the type of the excited spin-wave mode and its wavelength.
Generalized quantum Hall projection Hamiltonians
NASA Astrophysics Data System (ADS)
Simon, Steven H.; Rezayi, E. H.; Cooper, Nigel R.
2007-02-01
Certain well known quantum Hall states—including the Laughlin states, the Moore-Read Pfaffian, and the Read-Rezayi Parafermion states—can be defined as the unique lowest degree symmetric analytic function that vanishes as at least p powers as some number (g+1) of particles approach the same point. Analogously, these same quantum Hall states can be generated as the exact highest density zero energy state of simple angular momentum projection operators. Following this theme we determine the highest density zero energy state for many other values of p and g .
The Other Hall Effect: College Board Physics
ERIC Educational Resources Information Center
Sheppard, Keith; Gunning, Amanda M.
2013-01-01
Edwin Herbert Hall (1855-1938), discoverer of the Hall effect, was one of the first winners of the AAPT Oersted Medal for his contributions to the teaching of physics. While Hall's role in establishing laboratory work in high schools is widely acknowledged, his position as chair of the physics section of the Committee on College Entrance…
ERIC Educational Resources Information Center
Maxwell, Lesil A.
2008-01-01
This article features Beverly L. Hall, poised to become one of the longest-serving superintendents of the Atlanta schools. When she came to Atlanta in 1999, student achievement was sliding downward, teacher morale was dismal, and enrollment was falling as parents pulled their children out of the school system. Under the superintendent's driving…
Planar Hall effect bridge magnetic field sensors
Henriksen, A. D.; Dalslet, B. T.; Skieller, D. H.; Lee, K. H.; Okkels, F.; Hansen, M. F.
2010-07-05
Until now, the planar Hall effect has been studied in samples with cross-shaped Hall geometry. We demonstrate theoretically and experimentally that the planar Hall effect can be observed for an exchange-biased ferromagnetic material in a Wheatstone bridge topology and that the sensor signal can be significantly enhanced by a geometric factor. For the samples in the present study, we demonstrate an enhancement of the sensor output by a factor of about 100 compared to cross-shaped sensors. The presented construction opens a new design and application area of the planar Hall effect, which we term planar Hall effect bridge sensors.
Planar Hall effect bridge magnetic field sensors
NASA Astrophysics Data System (ADS)
Henriksen, A. D.; Dalslet, B. T.; Skieller, D. H.; Lee, K. H.; Okkels, F.; Hansen, M. F.
2010-07-01
Until now, the planar Hall effect has been studied in samples with cross-shaped Hall geometry. We demonstrate theoretically and experimentally that the planar Hall effect can be observed for an exchange-biased ferromagnetic material in a Wheatstone bridge topology and that the sensor signal can be significantly enhanced by a geometric factor. For the samples in the present study, we demonstrate an enhancement of the sensor output by a factor of about 100 compared to cross-shaped sensors. The presented construction opens a new design and application area of the planar Hall effect, which we term planar Hall effect bridge sensors.
The Other Hall Effect: College Board Physics
NASA Astrophysics Data System (ADS)
Sheppard, Keith; Gunning, Amanda M.
2013-09-01
Edwin Herbert Hall (1855-1938), discoverer of the Hall effect, was one of the first winners of the AAPT Oersted Medal for his contributions to the teaching of physics. While Hall's role in establishing laboratory work in high schools is widely acknowledged, his position as chair of the physics section of the Committee on College Entrance Requirements was contentious and his involvement in launching College Board Physics, what we call the "other Hall effect," has largely been overlooked. This article details Hall's role in the development of College Board Physics.
Optical Hall effect-model description: tutorial.
Schubert, Mathias; Kühne, Philipp; Darakchieva, Vanya; Hofmann, Tino
2016-08-01
The optical Hall effect is a physical phenomenon that describes the occurrence of magnetic-field-induced dielectric displacement at optical wavelengths, transverse and longitudinal to the incident electric field, and analogous to the static electrical Hall effect. The electrical Hall effect and certain cases of the optical Hall effect observations can be explained by extensions of the classic Drude model for the transport of electrons in metals. The optical Hall effect is most useful for characterization of electrical properties in semiconductors. Among many advantages, while the optical Hall effect dispenses with the need of electrical contacts, electrical material properties such as effective mass and mobility parameters, including their anisotropy as well as carrier type and density, can be determined from the optical Hall effect. Measurement of the optical Hall effect can be performed within the concept of generalized ellipsometry at an oblique angle of incidence. In this paper, we review and discuss physical model equations, which can be used to calculate the optical Hall effect in single- and multiple-layered structures of semiconductor materials. We define the optical Hall effect dielectric function tensor, demonstrate diagonalization approaches, and show requirements for the optical Hall effect tensor from energy conservation. We discuss both continuum and quantum approaches, and we provide a brief description of the generalized ellipsometry concept, the Mueller matrix calculus, and a 4×4 matrix algebra to calculate data accessible by experiment. In a follow-up paper, we will discuss strategies and approaches for experimental data acquisition and analysis.
Optical Hall effect-model description: tutorial.
Schubert, Mathias; Kühne, Philipp; Darakchieva, Vanya; Hofmann, Tino
2016-08-01
The optical Hall effect is a physical phenomenon that describes the occurrence of magnetic-field-induced dielectric displacement at optical wavelengths, transverse and longitudinal to the incident electric field, and analogous to the static electrical Hall effect. The electrical Hall effect and certain cases of the optical Hall effect observations can be explained by extensions of the classic Drude model for the transport of electrons in metals. The optical Hall effect is most useful for characterization of electrical properties in semiconductors. Among many advantages, while the optical Hall effect dispenses with the need of electrical contacts, electrical material properties such as effective mass and mobility parameters, including their anisotropy as well as carrier type and density, can be determined from the optical Hall effect. Measurement of the optical Hall effect can be performed within the concept of generalized ellipsometry at an oblique angle of incidence. In this paper, we review and discuss physical model equations, which can be used to calculate the optical Hall effect in single- and multiple-layered structures of semiconductor materials. We define the optical Hall effect dielectric function tensor, demonstrate diagonalization approaches, and show requirements for the optical Hall effect tensor from energy conservation. We discuss both continuum and quantum approaches, and we provide a brief description of the generalized ellipsometry concept, the Mueller matrix calculus, and a 4×4 matrix algebra to calculate data accessible by experiment. In a follow-up paper, we will discuss strategies and approaches for experimental data acquisition and analysis. PMID:27505654
Hall sensors for extreme temperatures.
Jankowski, Jakub; El-Ahmar, Semir; Oszwaldowski, Maciej
2011-01-01
We report on the preparation of the first complete extreme temperature Hall sensor. This means that the extreme-temperature magnetic sensitive semiconductor structure is built-in an extreme-temperature package especially designed for that purpose. The working temperature range of the sensor extends from -270 °C to +300 °C. The extreme-temperature Hall-sensor active element is a heavily n-doped InSb layer epitaxially grown on GaAs. The magnetic sensitivity of the sensor is ca. 100 mV/T and its temperature coefficient is less than 0.04 %/K. This sensor may find applications in the car, aircraft, spacecraft, military and oil and gas industries.
Electron dynamics in Hall thruster
NASA Astrophysics Data System (ADS)
Marini, Samuel; Pakter, Renato
2015-11-01
Hall thrusters are plasma engines those use an electromagnetic fields combination to confine electrons, generate and accelerate ions. Widely used by aerospace industries those thrusters stand out for its simple geometry, high specific impulse and low demand for electric power. Propulsion generated by those systems is due to acceleration of ions produced in an acceleration channel. The ions are generated by collision of electrons with propellant gas atoms. In this context, we can realize how important is characterizing the electronic dynamics. Using Hamiltonian formalism, we derive the electron motion equation in a simplified electromagnetic fields configuration observed in hall thrusters. We found conditions those must be satisfied by electromagnetic fields to have electronic confinement in acceleration channel. We present configurations of electromagnetic fields those maximize propellant gas ionization and thus make propulsion more efficient. This work was supported by CNPq.
Is The Intrinsic Spin Hall Effect Measurable?
NASA Astrophysics Data System (ADS)
Yang, Zhaoyang
2005-03-01
Despite of the large intrinsic spin Hall conductivity in a spin- orbit coupled material predicted theoretically, we show that the intrinsic spin Hall effect in any diffusive sample is not measurable via conventional transport methods, thus the research on the intrinsic spin Hall effect is limited at the pure theoretical content. After generally defining the intrinsic and extrinsic transport coefficients, we show that the intrinsic magnetization Hall current, which is the sum of the intrinsic spin and intrinsic orbit-angular-momentum Hall currents, is identically zero. More importantly, we demonstrate that the equation of motion for the spin density does not depend on the intrinsic spin Hall current, therefore the transverse spin accumulation is solely determined by the extrinsic spin Hall current. The zero intrinsic magnetization Hall current and the independence of the spin accumulation on the intrinsic spin Hall effect lead us to conclude that the intrinsic spin Hall effect can not be assessed by conventional spin transport experiments based on the measurement of the magnetization current and the spin accumulation at the edge of the sample.
Ionization oscillations in Hall accelerators
NASA Astrophysics Data System (ADS)
Barral, S.; Peradzyński, Z.
2010-01-01
The underlying mechanism of low-frequency oscillations in Hall accelerators is investigated theoretically. It is shown that relaxation oscillations arise from a competition between avalanche ionization and the advective transport of the working gas. The model derived recovers the slow progression and fast recession of the ionization front. Analytical approximations of the shape of current pulses and of the oscillation frequency are provided for the case of large amplitude oscillations.
Hyperbolic supersymmetric quantum Hall effect
Hasebe, Kazuki
2008-12-15
Developing a noncompact version of the supersymmetric Hopf map, we formulate the quantum Hall effect on a superhyperboloid. Based on OSp(1|2) group theoretical methods, we first analyze the one-particle Landau problem, and successively explore the many-body problem where the Laughlin wave function, hard-core pseudopotential Hamiltonian, and topological excitations are derived. It is also shown that the fuzzy superhyperboloid emerges at the lowest Landau level.
Fort Hall air emissions study, Fort Hall Indian Reservation, Fort Hall, Idaho
Metcalf, S.W.; Sonnenfeld, N.L.; Rolka, D.L.; Kaye, W.E.
1995-11-01
The Agency for Toxic Substances and Disease Registry (ATSDR) conducted a cross-sectional health study at the Fort Hall Indian Reservation in Idaho to investigate concerns about the health effects on reservation residents that might be attributed to two phosphate-processing plants located near the reservation`s southern border. In addition to increased particulates, air emissions from these plants included phosphorus pentoxide, cadmium, chromium, fluoride, uranium, and its daughter radionuclides. A total of 515 participants -- 229 from Fort Hall and 286 from a comparison group at the Duck Valley Indian Reservation -- were interviewed in person by trained American Indian interviewers. Approximately 100 residents of each reservation performed pulmonary function tests and provided urine specimens that were analyzed for cadmium, chromium, fluoride, and several renal biomarkers.
Observation of the Zero Hall Plateau in a Quantum Anomalous Hall Insulator.
Feng, Yang; Feng, Xiao; Ou, Yunbo; Wang, Jing; Liu, Chang; Zhang, Liguo; Zhao, Dongyang; Jiang, Gaoyuan; Zhang, Shou-Cheng; He, Ke; Ma, Xucun; Xue, Qi-Kun; Wang, Yayu
2015-09-18
We report experimental investigations on the quantum phase transition between the two opposite Hall plateaus of a quantum anomalous Hall insulator. We observe a well-defined plateau with zero Hall conductivity over a range of magnetic field around coercivity when the magnetization reverses. The features of the zero Hall plateau are shown to be closely related to that of the quantum anomalous Hall effect, but its temperature evolution exhibits a significant difference from the network model for a conventional quantum Hall plateau transition. We propose that the chiral edge states residing at the magnetic domain boundaries, which are unique to a quantum anomalous Hall insulator, are responsible for the novel features of the zero Hall plateau. PMID:26431002
NASA - 77M prototype hall thruster built under the High Voltage Hall accelerator development project
NASA Technical Reports Server (NTRS)
2005-01-01
NASA - 77M prototype hall thruster built under the High Voltage Hall accelerator development project funded by the Science Mission Directorate ; potential use is propulsion for deep space science missions
Listening to the acoustics in concert halls
NASA Astrophysics Data System (ADS)
Beranek, Leo L.; Griesinger, David
2001-05-01
How does acoustics affect the symphonic music performed in a concert hall? The lecture begins with an illustrated discussion of the architectural features that influence the acoustics. Boston Symphony Hall, which was built in 1900 when only one facet of architectural design was known, now rates as one of the world's great halls. How this occurred will be presented. Music is composed with some acoustical environment in mind and this varies with time from the Baroque to the Romantic to the Modern musical period. Conductors vary their interpretation according to the hall they are in. Well-traveled listeners and music critics have favorite halls. The lecture then presents a list of 58 halls rank ordered according to their acoustical quality based on interviews of music critics and conductors. Modern acoustical measurements made in these halls are compared with their rankings. Music recordings will be presented that demonstrate how halls sound that have different measured acoustical parameters. Photographs of a number of recently built halls are shown as examples of how these known acoustical factors have been incorporated into architectural design.
Anomalous Hall effect in localization regime
NASA Astrophysics Data System (ADS)
Wu, Lin; Zhu, Kai; Yue, Di; Tian, Yuan; Jin, Xiaofeng
2016-06-01
The anomalous Hall effect in the ultrathin film regime is investigated in Fe(001)(1-3 nm) films epitaxial on MgO(001). The logarithmic localization correction to longitudinal resistivity and anomalous Hall resistivity are observed at low temperature. We identify that the coefficient of skew scattering has a reduction from metallic to localized regime, while the contribution of side jump has inconspicuous change except for a small drop below 10 K. Furthermore, we discover that the intrinsic anomalous Hall conductivity decreases with the reduction of thickness below 2 nm. Our results provide unambiguous experimental evidence to clarify the problem of localization correction to the anomalous Hall effect.
Hall Thruster Technology for NASA Science Missions
NASA Technical Reports Server (NTRS)
Manzella, David; Oh, David; Aadland, Randall
2005-01-01
The performance of a prototype Hall thruster designed for Discovery-class NASA science mission applications was evaluated at input powers ranging from 0.2 to 2.9 kilowatts. These data were used to construct a throttle profile for a projected Hall thruster system based on this prototype thruster. The suitability of such a Hall thruster system to perform robotic exploration missions was evaluated through the analysis of a near Earth asteroid sample return mission. This analysis demonstrated that a propulsion system based on the prototype Hall thruster offers mission benefits compared to a propulsion system based on an existing ion thruster.
Anomalous Hall effect in ferromagnetic semiconductors.
Jungwirth, T; Niu, Qian; MacDonald, A H
2002-05-20
We present a theory of the anomalous Hall effect in ferromagnetic (III, Mn)V semiconductors. Our theory relates the anomalous Hall conductance of a homogeneous ferromagnet to the Berry phase acquired by a quasiparticle wave function upon traversing closed paths on the spin-split Fermi surface. The quantitative agreement between our theory and experimental data in both (In, Mn)As and (Ga, Mn)As systems suggests that this disorder independent contribution to the anomalous Hall conductivity dominates in diluted magnetic semiconductors. The success of this model for (III, Mn)V materials is unprecedented in the longstanding effort to understand origins of the anomalous Hall effect in itinerant ferromagnets.
Town Hall with Secretary Moniz
Energy Secretary Ernest Moniz; Deputy Secretary of Energy Daniel Poneman
2016-07-12
In a town hall meeting with Department staff, Energy Secretary Ernest Moniz spoke about his plans for a reorganization of the Energy Departmentâs management structure. The plans will help better achieve the Departmentâs key priorities and those of the President, including implementing the Presidentâs Climate Action Plan, âall of the aboveâ energy strategy and nuclear security agenda. After his remarks, Moniz, joined by Deputy Secretary Dan Poneman, took questions from the audience in the Forrestal Auditorium as well as email questions from other Department locations.
Rankin, R.A.; Kotter, D.K.
1997-05-13
The Hall-Effect Arc Protector is used to protect sensitive electronics from high energy arcs. The apparatus detects arcs by monitoring an electrical conductor, of the instrument, for changes in the electromagnetic field surrounding the conductor which would be indicative of a possible arcing condition. When the magnitude of the monitored electromagnetic field exceeds a predetermined threshold, the potential for an instrument damaging are exists and the control system logic activates a high speed circuit breaker. The activation of the breaker shunts the energy imparted to the input signal through a dummy load to the ground. After the arc condition is terminated, the normal signal path is restored. 2 figs.
Rankin, Richard A.; Kotter, Dale K.
1997-01-01
The Hall-Effect Arc Protector is used to protect sensitive electronics from high energy arcs. The apparatus detects arcs by monitoring an electrical conductor, of the instrument, for changes in the electromagnetic field surrounding the conductor which would be indicative of a possible arcing condition. When the magnitude of the monitored electromagnetic field exceeds a predetermined threshold, the potential for an instrument damaging are exists and the control system logic activates a high speed circuit breaker. The activation of the breaker shunts the energy imparted to the input signal through a dummy load to the ground. After the arc condition is terminated, the normal signal path is restored.
Temperature Gradient in Hall Thrusters
D. Staack; Y. Raitses; N.J. Fisch
2003-11-24
Plasma potentials and electron temperatures were deduced from emissive and cold floating probe measurements in a 2 kW Hall thruster, operated in the discharge voltage range of 200-400 V. An almost linear dependence of the electron temperature on the plasma potential was observed in the acceleration region of the thruster both inside and outside the thruster. This result calls into question whether secondary electron emission from the ceramic channel walls plays a significant role in electron energy balance. The proportionality factor between the axial electron temperature gradient and the electric field is significantly smaller than might be expected by models employing Ohmic heating of electrons.
Theory of Quantum Hall Nematics
NASA Astrophysics Data System (ADS)
Radzihovsky, Leo; Dorsey, Alan T.
2002-05-01
Transport measurements on two-dimensional electron systems in moderate magnetic fields suggest the existence of a spontaneously orientationally ordered, compressible liquid state. We develop and analyze a microscopic theory of such a ``quantum Hall nematic'' (QHN) phase, predict the existence of a novel, highly anisotropic q3 density-director mode, find that the T = 0 long-range orientational order is unstable to weak disorder, and compute the tunneling into such a strongly correlated state. This microscopic approach is supported and complemented by a hydrodynamic model of the QHN, which, in the dissipationless limit, reproduces the modes of the microscopic model.
Theory of quantum Hall nematics.
Radzihovsky, Leo; Dorsey, Alan T
2002-05-27
Transport measurements on two-dimensional electron systems in moderate magnetic fields suggest the existence of a spontaneously orientationally ordered, compressible liquid state. We develop and analyze a microscopic theory of such a "quantum Hall nematic" (QHN) phase, predict the existence of a novel, highly anisotropic q(3) density-director mode, find that the T = 0 long-range orientational order is unstable to weak disorder, and compute the tunneling into such a strongly correlated state. This microscopic approach is supported and complemented by a hydrodynamic model of the QHN, which, in the dissipationless limit, reproduces the modes of the microscopic model. PMID:12059490
Town Hall with Secretary Moniz
Energy Secretary Ernest Moniz; Deputy Secretary of Energy Daniel Poneman
2013-07-18
In a town hall meeting with Department staff, Energy Secretary Ernest Moniz spoke about his plans for a reorganization of the Energy Department’s management structure. The plans will help better achieve the Department’s key priorities and those of the President, including implementing the President’s Climate Action Plan, “all of the above” energy strategy and nuclear security agenda. After his remarks, Moniz, joined by Deputy Secretary Dan Poneman, took questions from the audience in the Forrestal Auditorium as well as email questions from other Department locations.
Electron Transport in Hall Thrusters
NASA Astrophysics Data System (ADS)
McDonald, Michael Sean
Despite high technological maturity and a long flight heritage, computer models of Hall thrusters remain dependent on empirical inputs and a large part of thruster development to date has been heavily experimental in nature. This empirical approach will become increasingly unsustainable as new high-power thrusters tax existing ground test facilities and more exotic thruster designs stretch and strain the boundaries of existing design experience. The fundamental obstacle preventing predictive modeling of Hall thruster plasma properties and channel erosion is the lack of a first-principles description of electron transport across the strong magnetic fields between the cathode and anode. In spite of an abundance of proposed transport mechanisms, accurate assessments of the magnitude of electron current due to any one mechanism are scarce, and comparative studies of their relative influence on a single thruster platform simply do not exist. Lacking a clear idea of what mechanism(s) are primarily responsible for transport, it is understandably difficult for the electric propulsion scientist to focus his or her theoretical and computational tools on the right targets. This work presents a primarily experimental investigation of collisional and turbulent Hall thruster electron transport mechanisms. High-speed imaging of the thruster discharge channel at tens of thousands of frames per second reveals omnipresent rotating regions of elevated light emission, identified with a rotating spoke instability. This turbulent instability has been shown through construction of an azimuthally segmented anode to drive significant cross-field electron current in the discharge channel, and suggestive evidence points to its spatial extent into the thruster near-field plume as well. Electron trajectory simulations in experimentally measured thruster electromagnetic fields indicate that binary collisional transport mechanisms are not significant in the thruster plume, and experiments
The fluctuation Hall conductivity and the Hall angle in type-II superconductor under magnetic field
NASA Astrophysics Data System (ADS)
Tinh, Bui Duc; Hoc, Nguyen Quang; Thu, Le Minh
2016-02-01
The fluctuation Hall conductivity and the Hall angle, describing the Hall effect, are calculated for arbitrary value of the imaginary part of the relaxation time in the frame of the time-dependent Ginzburg-Landau theory in type II-superconductor with thermal noise describing strong thermal fluctuations. The self-consistent Gaussian approximation is used to treat the nonlinear interaction term in dynamics. We obtain analytical expressions for the fluctuation Hall conductivity and the Hall angle summing all Landau levels without need to cutoff higher Landau levels to treat arbitrary magnetic field. The results are compared with experimental data on high-Tc superconductor.
Homogenization of the Three-dimensional Hall Effect and Change of Sign of the Hall Coefficient
NASA Astrophysics Data System (ADS)
Briane, Marc; Milton, Graeme W.
2009-09-01
The notion of a Hall matrix associated with a possibly anisotropic conducting material in the presence of a small magnetic field is introduced. Then, for any material having a microstructure we prove a general homogenization result satisfied by the Hall matrix in the framework of the H-convergence of Murat-Tartar. Extending a result of Bergman, we show that the Hall matrix can be computed from the corrector associated with the homogenization problem when no magnetic field is present. Finally, we give an example of a microstructure for which the Hall matrix is positive isotropic almost everywhere, while the homogenized Hall matrix is negative isotropic.
Technology Transfer Automated Retrieval System (TEKTRAN)
Agriculture in grassland environments is facing multiple stresses from: shifting demographics, declining and fragmented agricultural landscapes, declining environmental quality, variable and changing climate, volatile and increasing energy costs, marginal economic returns, and globalization. Degrad...
View of north front and west sides of hall, facing ...
View of north front and west sides of hall, facing south - International Longshoremen's & Warehousemen's Union Hall, Naval Civil Engineering Laboratory, Port Hueneme Road, Port Hueneme, Ventura County, CA
Interior detail of dispatch boards in main hall, facing west ...
Interior detail of dispatch boards in main hall, facing west - International Longshoremen's & Warehousemen's Union Hall, Naval Civil Engineering Laboratory, Port Hueneme Road, Port Hueneme, Ventura County, CA
Survey of Residence Hall Life at NCSU.
ERIC Educational Resources Information Center
Dolin, Nancy C.
A 1977 North Carolina State University survey of a sample of on-campus students determined their attitudes toward residence hall activities, facilities, and staff. Information is shown by sex, class, and residence hall, and totals are weighted to reflect actual proportions in each dorm. Among the findings are the following: cookouts, movies, beer…
Metal-Film Hall-Effect Devices
NASA Technical Reports Server (NTRS)
Peters, Palmer N.
1994-01-01
Large positive and negative Hall coefficients achievable. Family of Hall-effect devices made from multilayer metal films instead of semiconductor materials. Metal films easier to fabricate; formed by deposition on variety of substrates, and leads readily attached to them. Fabricated with larger areas, potentially more reliable, and less affected by impurities. Also used to measure magnetic fields. Devices especially useful at low temperatures.
Concert Halls of Chicago Under Theodore Thomas.
ERIC Educational Resources Information Center
Olsen, Dale A.
1983-01-01
Describes the musical history of Chicago, which culminated in the creation of the Chicago Symphony and the construction of Orchestra Hall. Theodore Thomas spent 30 years introducing Chicagoans to symphonic music. He founded the Chicago Symphony and, in 1904, led the first concert in Orchestra Hall. (CS)
19th Annual Residence Hall Construction Report
ERIC Educational Resources Information Center
Agron, Joe
2008-01-01
The construction of residence hall facilities at colleges and universities continues to be strong, as institutions scramble to meet the housing needs and varied demands of a growing student population. This article presents data collected from 39 new residence hall projects completed in 2007. According to American School & University's 19th annual…
20th Annual Residence Hall Construction Report
ERIC Educational Resources Information Center
Agron, Joe
2009-01-01
Even in difficult economic times, colleges and universities continue to invest in residence hall construction projects as a way to attract new students and keep existing ones on campus. According to data from "American School & University"'s 20th annual Residence Hall Construction Report, the median new project completed in 2008 was less expensive…
ERIC Educational Resources Information Center
Training, 2012
2012-01-01
Microsoft Corporation and SCC Soft Computer are the newest inductees into the Training Top 10 Hall of Fame, joining the ranks of the 11 companies named to the hall since its inception in 2008 (Wyeth Pharmaceuticals subsequently was acquired by Pfizer Inc. in 2009). These 11 companies held Top 10 spots in the Training Top 50, Top 100, and now Top…
The Scientific Humanism of G. Stanley Hall
ERIC Educational Resources Information Center
Meyer, Donald H.
1971-01-01
This paper presents the humanistic psychology of the pioneer American psychologist Granville Stanley Hall (1844-1924), examining Hall's effort to develop a system of psychology that is at once rigorously scientific and, simultaneously, capable of verifying essential human values. (Author)
Sport for All. Low Cost Sports Halls.
ERIC Educational Resources Information Center
Council of Europe, Strasbourg (France).
This report of the conference on low-cost sports halls, sponsored by the Council of Europe, is divided into two sections: technical studies and conclusions. The introduction to the report provides an overview of the long-term program of the Council of Europe with regard to sport for all and a discussion of multipurpose sports halls. Sociocultural,…
Quantum Hall effect in quantum electrodynamics
Penin, Alexander A.
2009-03-15
We consider the quantum Hall effect in quantum electrodynamics and find a deviation from the quantum-mechanical prediction for the Hall conductivity due to radiative antiscreening of electric charge in an external magnetic field. A weak dependence of the universal von Klitzing constant on the magnetic field strength, which can possibly be observed in a dedicated experiment, is predicted.
ERIC Educational Resources Information Center
Lehigh County Area Vocational-Technical School, Schnecksville, PA.
This brochure describes the philosophy and scope of a secondary-level course in agricultural production. Addressed in the individual units of the course are the following topics: careers in agriculture and agribusiness, animal science and livestock production, agronomy, agricultural mechanics, supervised occupational experience programs, and the…
Flexible Hall sensors based on graphene
NASA Astrophysics Data System (ADS)
Wang, Zhenxing; Shaygan, Mehrdad; Otto, Martin; Schall, Daniel; Neumaier, Daniel
2016-03-01
The excellent electronic and mechanical properties of graphene provide a perfect basis for high performance flexible electronic and sensor devices. Here, we present the fabrication and characterization of flexible graphene based Hall sensors. The Hall sensors are fabricated on 50 μm thick flexible Kapton foil using large scale graphene grown by chemical vapor deposition technique on copper foil. Voltage and current normalized sensitivities of up to 0.096 V VT-1 and 79 V AT-1 were measured, respectively. These values are comparable to the sensitivity of rigid silicon based Hall sensors and are the highest values reported so far for any flexible Hall sensor devices. The sensitivity of the Hall sensor shows no degradation after being bent to a minimum radius of 4 mm, which corresponds to a tensile strain of 0.6%, and after 1000 bending cycles to a radius of 5 mm.
Flexible Hall sensors based on graphene.
Wang, Zhenxing; Shaygan, Mehrdad; Otto, Martin; Schall, Daniel; Neumaier, Daniel
2016-04-14
The excellent electronic and mechanical properties of graphene provide a perfect basis for high performance flexible electronic and sensor devices. Here, we present the fabrication and characterization of flexible graphene based Hall sensors. The Hall sensors are fabricated on 50 μm thick flexible Kapton foil using large scale graphene grown by chemical vapor deposition technique on copper foil. Voltage and current normalized sensitivities of up to 0.096 V VT(-1) and 79 V AT(-1) were measured, respectively. These values are comparable to the sensitivity of rigid silicon based Hall sensors and are the highest values reported so far for any flexible Hall sensor devices. The sensitivity of the Hall sensor shows no degradation after being bent to a minimum radius of 4 mm, which corresponds to a tensile strain of 0.6%, and after 1000 bending cycles to a radius of 5 mm.
Xue, Ling; Zhang, Panpan; Shu, Huajie; Chang, Chein-Chi; Wang, Renqing; Zhang, Shuping
2016-10-01
In recent years, the quantity of agricultural waste has been rising rapidly all over the world. As a result, the environmental problems and negative impacts of agricultural waste are drawn more and more attention. Therefore, there is a need to adopt proper approaches to reduce and reuse agricultural waste. This review presented about 200 literatures published in 2015 relating to the topic of agricultural waste. The review examined research on agricultural waste in 2015 from the following four aspects: the characterization, reuse, treatment, and management. Researchers highlighted the importance to reuse agricultural waste and investigated the potential to utilize it as biofertilizers, cultivation material, soil amendments, adsorbent, material, energy recycling, enzyme and catalyst etc. The treatment of agricultural waste included carbonization, biodegradation, composting hydrolysis and pyrolysis. Moreover, this review analyzed the differences of the research progress in 2015 from 2014. It may help to reveal the new findings and new trends in this field in 2015 comparing to 2014. PMID:27620093
Xue, Ling; Zhang, Panpan; Shu, Huajie; Chang, Chein-Chi; Wang, Renqing; Zhang, Shuping
2016-10-01
In recent years, the quantity of agricultural waste has been rising rapidly all over the world. As a result, the environmental problems and negative impacts of agricultural waste are drawn more and more attention. Therefore, there is a need to adopt proper approaches to reduce and reuse agricultural waste. This review presented about 200 literatures published in 2015 relating to the topic of agricultural waste. The review examined research on agricultural waste in 2015 from the following four aspects: the characterization, reuse, treatment, and management. Researchers highlighted the importance to reuse agricultural waste and investigated the potential to utilize it as biofertilizers, cultivation material, soil amendments, adsorbent, material, energy recycling, enzyme and catalyst etc. The treatment of agricultural waste included carbonization, biodegradation, composting hydrolysis and pyrolysis. Moreover, this review analyzed the differences of the research progress in 2015 from 2014. It may help to reveal the new findings and new trends in this field in 2015 comparing to 2014.
Theory of Quantum Hall Nematics
NASA Astrophysics Data System (ADS)
Radzihovsky, Leo; Dorsey, Alan
2002-03-01
Transport measurements on two dimensional electron systems in moderate magnetic fields suggest the existence of a spontaneously orientationally-ordered, compressible liquid state. We develop and analyze [1] a microscopic theory of such a ``quantum Hall nematic'' (QHN) phase, predict the existence of a novel, highly anisotropic q^3 density-director mode, find that the T=0 long-range orientational order is unstable to weak disorder, and compute the tunneling into such a strongly correlated state. This microscopic approach is supported and complemented by a hydrodynamic model of the QHN, which, in the dissipationless limit, reproduces the modes of the microscopic model. This research was supported by NSF DMR-9978547, DMR-9625111, and the Sloan and Packard Foundations. [1] L. Radzihovsky and A. T. Dorsey, cond-mat/0110083
The quantum Hall impedance standard
NASA Astrophysics Data System (ADS)
Schurr, J.; Kučera, J.; Pierz, K.; Kibble, B. P.
2011-02-01
Alternating current measurements of double-shielded quantum Hall devices have revealed a fascinating property of which only a quantum effect is capable: it can detect its own frequency dependence and convert it to a current dependence which can be used to eliminate both of them. According to an experimentally verified model, the residual frequency dependence is smaller than the measuring uncertainty of 1.3 × 10-9 kHz-1. In this way, a highly precise quantum standard of impedance can be established, without having to correct for any calculated frequency dependence and without the need for any artefact with a calculated frequency dependence. Nothing else like that is known to us and we hope that our results encourage other national metrology institutes to also apply it to impedance metrology and further explore its beautiful properties.
The quantum Hall effect helicity
Shrivastava, Keshav N.
2015-04-16
The quantum Hall effect in semiconductor heterostructures is explained by two signs in the angular momentum j=l±s and g=(2j+1)/(2l+1) along with the Landau factor (n+1/2). These modifications in the existing theories explain all of the fractional charges. The helicity which is the sign of the product of the linear momentum with the spin p.s plays an important role for the understanding of the data at high magnetic fields. In particular it is found that particles with positive sign in the spin move in one direction and those with negative sign move in another direction which explains the up and down stream motion of the particles.
Predicting Hall Thruster Operational Lifetime
NASA Technical Reports Server (NTRS)
Manzella, David; Yim, John; Boyd, Iain
2004-01-01
A simple analytic model predicted Hall thruster channel erosion based on thruster geometry, operating conditions, and magnetic field configuration. This model relied on a one-dimensional representation of the plasma with a fixed ionization fraction and variable ion energies based on the magnetic field distribution. Sputtering was modeled as the result of elastic scattering of ions by neutrals within the channel. Not all scattered ions and neutrals were assumed to reach the channel walls as a result of additional subsequent scattering events. Incorporating this phenomenon resulted in a greater predicted decrease in erosion rate with time than predicted based only on geometric effects. Results from this model were compared to SPT 100 experimental erosion data.
Generalized Clustered Quantum Hall States
NASA Astrophysics Data System (ADS)
Simon, Steven H.; Cooper, Nigel R.; Rezayi, Ed
2005-03-01
The Read-Rezayi (parafermion) quantum Hall states[1] for bosons can be defined as states where the wavefunction does not vanish when g bosons come together to the same point, but does vanish as z^2 as a g+1st particle approaches that point. These states can equivalently be defined as the unique ground state of a point contact g+1 particle interaction Hamiltonian. Interestingly, the series of Read-Rezayi states appears to describe well the groundstates of rotating Bose condensates with point-contact two body interactions at a series of filling fractions [2]. If one attaches a Jastrow factor to such bose wavefunctions, one obtains fermion wavefunctions that may occur in electronic quantum Hall systems including the (g=2) Pfaffian [3] and the (g=3) ν=13/5 Read-Rezayi state [1]. In this work, we consider generalized cluster wavefunctions defined by the algebraic manner in which a wavefunction vanishes as g+1 particles coalesce. We find Hamiltonians that generate these wavefunctions as their exact ground state. Among this series of states is the previously studied Haffnian wavefunction[4] and a host of states not previously discussed. We catalogue and study the new states and discuss whether any of them might occur in actual physical systems. [1] N. Read and E. Rezayi, PRB59, 8084 (1999). [2] N. R. Cooper, N. K. Wilkin, and J. M. F. Gunn, PRL87, 120405 (2001) [3] G. Moore and N. Read, Nuc. Phys. B360, 362 (1991). [4] D. Green, PhD Thesis.
Hall magnetoresistivity response under microwave excitation revisited
Inarrea, Jesus
2007-04-23
The authors theoretically analyzed the microwave-induced modification of the Hall magnetoresistivity in high mobility two-dimensional electron systems. These systems present diagonal magnetoresistivity oscillations and zero-resistance states when subjected to microwave radiation. The most surprising modification of the Hall magnetoresistivity is a periodic reduction which correlates with a periodic increase in the diagonal resistivity. The authors present a model that explains the experimental results considering that radiation affects directly only the diagonal resistivity and that the observed Hall resistivity changes come from the tensor relationship between them.
Piezo Voltage Controlled Planar Hall Effect Devices
NASA Astrophysics Data System (ADS)
Zhang, Bao; Meng, Kang-Kang; Yang, Mei-Yin; Edmonds, K. W.; Zhang, Hao; Cai, Kai-Ming; Sheng, Yu; Zhang, Nan; Ji, Yang; Zhao, Jian-Hua; Zheng, Hou-Zhi; Wang, Kai-You
2016-06-01
The electrical control of the magnetization switching in ferromagnets is highly desired for future spintronic applications. Here we report on hybrid piezoelectric (PZT)/ferromagnetic (Co2FeAl) devices in which the planar Hall voltage in the ferromagnetic layer is tuned solely by piezo voltages. The change of planar Hall voltage is associated with magnetization switching through 90° in the plane under piezo voltages. Room temperature magnetic NOT and NOR gates are demonstrated based on the piezo voltage controlled Co2FeAl planar Hall effect devices without the external magnetic field. Our demonstration may lead to the realization of both information storage and processing using ferromagnetic materials.
Chiral thermoelectrics with quantum Hall edge states.
Sánchez, Rafael; Sothmann, Björn; Jordan, Andrew N
2015-04-10
The thermoelectric properties of a three-terminal quantum Hall conductor are investigated. We identify a contribution to the thermoelectric response that relies on the chirality of the carrier motion rather than on spatial asymmetries. The Onsager matrix becomes maximally asymmetric with configurations where either the Seebeck or the Peltier coefficients are zero while the other one remains finite. Reversing the magnetic field direction exchanges these effects, which originate from the chiral nature of the quantum Hall edge states. The possibility to generate spin-polarized currents in quantum spin Hall samples is discussed. PMID:25910147
Chiral Thermoelectrics with Quantum Hall Edge States
NASA Astrophysics Data System (ADS)
Sánchez, Rafael; Sothmann, Björn; Jordan, Andrew N.
2015-04-01
The thermoelectric properties of a three-terminal quantum Hall conductor are investigated. We identify a contribution to the thermoelectric response that relies on the chirality of the carrier motion rather than on spatial asymmetries. The Onsager matrix becomes maximally asymmetric with configurations where either the Seebeck or the Peltier coefficients are zero while the other one remains finite. Reversing the magnetic field direction exchanges these effects, which originate from the chiral nature of the quantum Hall edge states. The possibility to generate spin-polarized currents in quantum spin Hall samples is discussed.
The quantum Hall effects: Philosophical approach
NASA Astrophysics Data System (ADS)
Lederer, P.
2015-05-01
The Quantum Hall Effects offer a rich variety of theoretical and experimental advances. They provide interesting insights on such topics as gauge invariance, strong interactions in Condensed Matter physics, emergence of new paradigms. This paper focuses on some related philosophical questions. Various brands of positivism or agnosticism are confronted with the physics of the Quantum Hall Effects. Hacking's views on Scientific Realism, Chalmers' on Non-Figurative Realism are discussed. It is argued that the difficulties with those versions of realism may be resolved within a dialectical materialist approach. The latter is argued to provide a rational approach to the phenomena, theory and ontology of the Quantum Hall Effects.
Direct Drive for Low Power Hall Thrusters
NASA Technical Reports Server (NTRS)
Dankanich, John W.
2005-01-01
Due to recent studies, NASA has initiated the development of a low power Hall thruster for discovery class missions. The potential advantages of a low power Hall thruster is primarily due to its high efficiency operation at low power and its lower complexity compared to ion engines. Direct drive is another method of reducing the complexity of a Hall thruster system while improving its efficiency. The technical challenges associated with this technology are reported. Additionally, the benefits of this technology are discussed based on parametric studies and mission analysis.
Joule heating in spin Hall geometry
NASA Astrophysics Data System (ADS)
Taniguchi, Tomohiro
2016-07-01
The theoretical formula for the entropy production rate in the presence of spin current is derived using the spin-dependent transport equation and thermodynamics. This theory is applicable regardless of the source of the spin current, for example, an electric field, a temperature gradient, or the Hall effect. It reproduces the result in a previous work on the dissipation formula when the relaxation time approximation is applied to the spin relaxation rate. By using the developed theory, it is found that the dissipation in the spin Hall geometry has a contribution proportional to the square of the spin Hall angle.
Piezo Voltage Controlled Planar Hall Effect Devices.
Zhang, Bao; Meng, Kang-Kang; Yang, Mei-Yin; Edmonds, K W; Zhang, Hao; Cai, Kai-Ming; Sheng, Yu; Zhang, Nan; Ji, Yang; Zhao, Jian-Hua; Zheng, Hou-Zhi; Wang, Kai-You
2016-06-22
The electrical control of the magnetization switching in ferromagnets is highly desired for future spintronic applications. Here we report on hybrid piezoelectric (PZT)/ferromagnetic (Co2FeAl) devices in which the planar Hall voltage in the ferromagnetic layer is tuned solely by piezo voltages. The change of planar Hall voltage is associated with magnetization switching through 90° in the plane under piezo voltages. Room temperature magnetic NOT and NOR gates are demonstrated based on the piezo voltage controlled Co2FeAl planar Hall effect devices without the external magnetic field. Our demonstration may lead to the realization of both information storage and processing using ferromagnetic materials.
Ezawa, Motohiko
2013-12-04
Silicene is a monolayer of silicon atoms forming a two-dimensional honeycomb lattice, which shares almost every remarkable property with graphene. The low energy dynamics is described by Dirac electrons, but they are massive due to relatively large spin-orbit interactions. I will explain the following properties of silicene: 1) The band structure is controllable by applying an electric field. 2) Silicene undergoes a phase transition from a topological insulator to a band insulator by applying external electric field. 3) The topological phase transition can be detected experimentally by way of diamagnetism. 4) There is a novel valley-spin selection rules revealed by way of photon absorption. 5) Silicene yields a remarkably many phases such as quantum anomalous Hall phase and valley polarized metal when the exchange field is additionally introduced. 6) A silicon nanotubes can be used to convey spin currents under an electric field.
Topologically induced fractional Hall steps in the integer quantum Hall regime of MoS 2
NASA Astrophysics Data System (ADS)
Firoz Islam, SK; Benjamin, Colin
2016-09-01
The quantum magnetotransport properties of a monolayer of molybdenum disulfide are derived using linear response theory. In particular, the effect of topological terms on longitudinal and Hall conductivity is analyzed. The Hall conductivity exhibits fractional steps in the integer quantum Hall regime. Further complete spin and valley polarization of the longitudinal conductivitity is seen in presence of these topological terms. Finally, the Shubnikov-de Hass oscillations are suppressed or enhanced contingent on the sign of these topological terms.
Topologically induced fractional Hall steps in the integer quantum Hall regime of MoS 2.
Islam, S K Firoz; Benjamin, Colin
2016-09-23
The quantum magnetotransport properties of a monolayer of molybdenum disulfide are derived using linear response theory. In particular, the effect of topological terms on longitudinal and Hall conductivity is analyzed. The Hall conductivity exhibits fractional steps in the integer quantum Hall regime. Further complete spin and valley polarization of the longitudinal conductivitity is seen in presence of these topological terms. Finally, the Shubnikov-de Hass oscillations are suppressed or enhanced contingent on the sign of these topological terms.
Topologically induced fractional Hall steps in the integer quantum Hall regime of MoS 2.
Islam, S K Firoz; Benjamin, Colin
2016-09-23
The quantum magnetotransport properties of a monolayer of molybdenum disulfide are derived using linear response theory. In particular, the effect of topological terms on longitudinal and Hall conductivity is analyzed. The Hall conductivity exhibits fractional steps in the integer quantum Hall regime. Further complete spin and valley polarization of the longitudinal conductivitity is seen in presence of these topological terms. Finally, the Shubnikov-de Hass oscillations are suppressed or enhanced contingent on the sign of these topological terms. PMID:27533362
Quantum Hall effect in momentum space
NASA Astrophysics Data System (ADS)
Ozawa, Tomoki; Price, Hannah M.; Carusotto, Iacopo
2016-05-01
We theoretically discuss a momentum-space analog of the quantum Hall effect, which could be observed in topologically nontrivial lattice models subject to an external harmonic trapping potential. In our proposal, the Niu-Thouless-Wu formulation of the quantum Hall effect on a torus is realized in the toroidally shaped Brillouin zone. In this analogy, the position of the trap center in real space controls the magnetic fluxes that are inserted through the holes of the torus in momentum space. We illustrate the momentum-space quantum Hall effect with the noninteracting trapped Harper-Hofstadter model, for which we numerically demonstrate how this effect manifests itself in experimental observables. Extension to the interacting trapped Harper-Hofstadter model is also briefly considered. We finally discuss possible experimental platforms where our proposal for the momentum-space quantum Hall effect could be realized.
Hall Opens Doors to Astronaut Heroes
Space shuttle astronauts Bonnie Dunbar, Curt Brown and Eileen Collins joined an elite group of American space heroes as they were inducted into the U.S. Astronaut Hall of Fame on April 20, during a...
Boundary Effective Action for Quantum Hall States
NASA Astrophysics Data System (ADS)
Gromov, Andrey; Jensen, Kristan; Abanov, Alexander G.
2016-03-01
We consider quantum Hall states on a space with boundary, focusing on the aspects of the edge physics which are completely determined by the symmetries of the problem. There are four distinct terms of Chern-Simons type that appear in the low-energy effective action of the state. Two of these protect gapless edge modes. They describe Hall conductance and, with some provisions, thermal Hall conductance. The remaining two, including the Wen-Zee term, which contributes to the Hall viscosity, do not protect gapless edge modes but are instead related to the local boundary response fixed by symmetries. We highlight some basic features of this response. It follows that the coefficient of the Wen-Zee term can change across an interface without closing a gap or breaking a symmetry.
The phonon Hall effect: theory and application.
Zhang, Lifa; Ren, Jie; Wang, Jian-Sheng; Li, Baowen
2011-08-01
We present a systematic theory of the phonon Hall effect in a ballistic crystal lattice system, and apply it on the kagome lattice which is ubiquitous in various real materials. By proposing a proper second quantization for the non-Hermitian in the polarization-vector space, we obtain a new heat current density operator with two separate contributions: the normal velocity responsible for the longitudinal phonon transport, and the anomalous velocity manifesting itself as the Hall effect of transverse phonon transport. As exemplified in kagome lattices, our theory predicts that the direction of Hall conductivity at low magnetic field can be reversed by tuning the temperatures, which we hope can be verified by experiments in the future. Three phonon-Hall-conductivity singularities induced by phonon-band-topology change are discovered as well, which correspond to the degeneracies at three different symmetric center points, Γ, K, X, in the wavevector space of the kagome lattice.
Quantum anomalous Hall effect with higher plateaus.
Wang, Jing; Lian, Biao; Zhang, Haijun; Xu, Yong; Zhang, Shou-Cheng
2013-09-27
The quantum anomalous Hall (QAH) effect in magnetic topological insulators is driven by the combination of spontaneous magnetic moments and spin-orbit coupling. Its recent experimental discovery raises the question if higher plateaus can also be realized. Here, we present a general theory for a QAH effect with higher Chern numbers and show by first-principles calculations that a thin film magnetic topological insulator of Cr-doped Bi2(Se,Te)3 is a candidate for the C=2 QAH insulator. Remarkably, whereas a higher magnetic field leads to lower Hall conductance plateaus in the integer quantum Hall effect, a higher magnetic moment leads to higher Hall conductance plateaus in the QAH effect.
Hall viscosity revealed via density response
NASA Astrophysics Data System (ADS)
Huang, Biao
2015-06-01
Quantum Hall systems have recently been shown to possess a quantity sensitive to the spatial geometry and topology of the system, dubbed the Hall viscosity ηH. Despite the extensive theoretical discussions on its properties, the question of how to measure ηH still poses a challenge. In this paper, we present a general relation between Hall viscosity and susceptibility for systems with Galilean invariance. Thus, it allows for determination of ηH through density response signatures. The relations are verified in the integer quantum Hall example and are further illustrated in an effective hydrodynamic analysis. Since the derivation is based on Kubo formulas and assumes no more than conservation laws and translational symmetry, the results are applicable to a wide range of systems.
Protecting Your Residence Hall Furniture Investment.
ERIC Educational Resources Information Center
Wiens, Janet
2003-01-01
Asserting that residence hall furniture takes abuse simply through use, discusses a three-part approach--student involvement and education, creating the right environment, and ongoing maintenance--that helps reduce normal wear and tear. (EV)
Boundary Effective Action for Quantum Hall States.
Gromov, Andrey; Jensen, Kristan; Abanov, Alexander G
2016-03-25
We consider quantum Hall states on a space with boundary, focusing on the aspects of the edge physics which are completely determined by the symmetries of the problem. There are four distinct terms of Chern-Simons type that appear in the low-energy effective action of the state. Two of these protect gapless edge modes. They describe Hall conductance and, with some provisions, thermal Hall conductance. The remaining two, including the Wen-Zee term, which contributes to the Hall viscosity, do not protect gapless edge modes but are instead related to the local boundary response fixed by symmetries. We highlight some basic features of this response. It follows that the coefficient of the Wen-Zee term can change across an interface without closing a gap or breaking a symmetry. PMID:27058090
Hall effect degradation of rail gun performance
NASA Astrophysics Data System (ADS)
Witalis, E. A.; Gunnarsson, Patrik
1993-01-01
The paper discusses the Hall effect and shows it to be significant in the low-density and high-field trailing part of a plasma armature. Without the Hall effect a simple armature model is derived. It exhibits properties expected from classical MHD theory and shows that the purely relativistic electric charge buildup on the rails is a fundamental gun property, leading to V(breech) = 1.5 V(muzzle). The mathematics involved in accounting for Hall effect phenomena is described. These are of two types: the Hall-skewing of the armature current and the superimposed plasma flow rotation. For decreasing gun current the two effects efficiently combine to eject armature plasma rearwards, thus creating conditions for arc separation and parasitic arcs.
Boundary Effective Action for Quantum Hall States.
Gromov, Andrey; Jensen, Kristan; Abanov, Alexander G
2016-03-25
We consider quantum Hall states on a space with boundary, focusing on the aspects of the edge physics which are completely determined by the symmetries of the problem. There are four distinct terms of Chern-Simons type that appear in the low-energy effective action of the state. Two of these protect gapless edge modes. They describe Hall conductance and, with some provisions, thermal Hall conductance. The remaining two, including the Wen-Zee term, which contributes to the Hall viscosity, do not protect gapless edge modes but are instead related to the local boundary response fixed by symmetries. We highlight some basic features of this response. It follows that the coefficient of the Wen-Zee term can change across an interface without closing a gap or breaking a symmetry.
ERIC Educational Resources Information Center
Jewell, W. J.; Switzenbaum, M. S.
1978-01-01
Presents a literature review of agricultural wastes, covering publications of 1976-77. Some of the areas covered are: (1) water characteristics and impacts; (2) waste treatment; (3) reuse of agricultural wastes; and (4) nonpoint pollution sources. A list of 150 references is also presented. (HM)
ERIC Educational Resources Information Center
California State Dept. of Education, Sacramento. Research Coordinating Unit.
TO ASSIST THOSE WHO MAKE DECISIONS RELATING TO EDUCATIONAL PROGRAMS IN AGRICULTURE, RECENT RESEARCH IN VOCATIONAL AGRICULTURE IS SUMMARIZED. A 1963 STUDY TREATS THE RELATIONSHIP BETWEEN WORK EXPERIENCE AND STUDENT CHARACTERISTICS, PLANS, AND ASPIRATIONS. STUDIES ON POST-SECONDARY EDUCATION CONCERN GUIDELINES FOR TECHNICIAN PROGRAMS, JUSTIFICATION…
Galilean invariance at quantum Hall edge
NASA Astrophysics Data System (ADS)
Moroz, Sergej; Hoyos, Carlos; Radzihovsky, Leo
2015-05-01
We construct the theory of a chiral Luttinger liquid that lives on the boundary of a Galilean invariant quantum Hall fluid. In contrast to previous studies, Galilean invariance of the total (bulk plus edge) theory is guaranteed. We consider electromagnetic response at the edge and calculate momentum- and frequency-dependent electric conductivity and argue that its experimental measurement can provide a new means to determine the "shift" and bulk Hall viscosity.
Quantum hall effect at low magnetic fields
Huckestein
2000-04-01
The temperature and scale dependence of resistivities in the standard scaling theory of the integer quantum Hall effect is discussed. It is shown that recent experiments, claiming to observe a discrepancy with the global phase diagram of the quantum Hall effect, are in fact in agreement with the standard theory. The apparent low-field transition observed in the experiments is identified as a crossover due to weak localization and a strong reduction of the conductivity when Landau quantization becomes dominant.
Energy magnetization and the thermal Hall effect.
Qin, Tao; Niu, Qian; Shi, Junren
2011-12-01
We obtain a set of general formulas for determining magnetizations, including the usual electromagnetic magnetization as well as the gravitomagnetic energy magnetization. The magnetization corrections to the thermal transport coefficients are explicitly demonstrated. Our theory provides a systematic approach for properly evaluating the thermal transport coefficients of magnetic systems, eliminating the unphysical divergence from the direct application of the Kubo formula. For a noninteracting anomalous Hall system, the corrected thermal Hall conductivity obeys the Wiedemann-Franz law.
Integer quantum Hall effect for bosons.
Senthil, T; Levin, Michael
2013-01-25
A simple physical realization of an integer quantum Hall state of interacting two dimensional bosons is provided. This is an example of a symmetry-protected topological (SPT) phase which is a generalization of the concept of topological insulators to systems of interacting bosons or fermions. Universal physical properties of the boson integer quantum Hall state are described and shown to correspond with those expected from general classifications of SPT phases.
Observation of a superfluid Hall effect
Jiménez-García, Karina; Williams, Ross A.; Beeler, Matthew C.; Perry, Abigail R.; Phillips, William D.; Spielman, Ian B.
2012-01-01
Measurement techniques based upon the Hall effect are invaluable tools in condensed-matter physics. When an electric current flows perpendicular to a magnetic field, a Hall voltage develops in the direction transverse to both the current and the field. In semiconductors, this behavior is routinely used to measure the density and charge of the current carriers (electrons in conduction bands or holes in valence bands)—internal properties of the system that are not accessible from measurements of the conventional resistance. For strongly interacting electron systems, whose behavior can be very different from the free electron gas, the Hall effect’s sensitivity to internal properties makes it a powerful tool; indeed, the quantum Hall effects are named after the tool by which they are most distinctly measured instead of the physics from which the phenomena originate. Here we report the first observation of a Hall effect in an ultracold gas of neutral atoms, revealed by measuring a Bose–Einstein condensate’s transport properties perpendicular to a synthetic magnetic field. Our observations in this vortex-free superfluid are in good agreement with hydrodynamic predictions, demonstrating that the system’s global irrotationality influences this superfluid Hall signal. PMID:22699494
Hierarchical nature of the quantum Hall effects.
Bonderson, Parsa
2012-02-10
I demonstrate that the wave function for a ν=n+ν[over ˜] quantum Hall state with Landau levels 0,1,…,n-1 filled and a filling fraction ν[over ˜] quantum Hall state with 0<ν[over ˜]≤1 in the nth Landau level can be obtained hierarchically from the ν=n state by introducing quasielectrons which are then projected into the (conjugate of the) ν[over ˜] state. In particular, the ν[over ˜]=1 case produces the filled Landau level wave functions hierarchically, thus establishing the hierarchical nature of the integer quantum Hall states. It follows that the composite fermion description of fractional quantum Hall states fits within the hierarchy theory of the fractional quantum Hall effect. I also demonstrate this directly by generating the composite fermion ground-state wave functions via application of the hierarchy construction to fractional quantum Hall states, starting from the ν=1/m Laughlin states.
Observation of a superfluid Hall effect.
LeBlanc, Lindsay J; Jiménez-García, Karina; Williams, Ross A; Beeler, Matthew C; Perry, Abigail R; Phillips, William D; Spielman, Ian B
2012-07-01
Measurement techniques based upon the Hall effect are invaluable tools in condensed-matter physics. When an electric current flows perpendicular to a magnetic field, a Hall voltage develops in the direction transverse to both the current and the field. In semiconductors, this behavior is routinely used to measure the density and charge of the current carriers (electrons in conduction bands or holes in valence bands)--internal properties of the system that are not accessible from measurements of the conventional resistance. For strongly interacting electron systems, whose behavior can be very different from the free electron gas, the Hall effect's sensitivity to internal properties makes it a powerful tool; indeed, the quantum Hall effects are named after the tool by which they are most distinctly measured instead of the physics from which the phenomena originate. Here we report the first observation of a Hall effect in an ultracold gas of neutral atoms, revealed by measuring a Bose-Einstein condensate's transport properties perpendicular to a synthetic magnetic field. Our observations in this vortex-free superfluid are in good agreement with hydrodynamic predictions, demonstrating that the system's global irrotationality influences this superfluid Hall signal.
Agriculture Education. Agricultural Metal Working.
ERIC Educational Resources Information Center
Stuttgart Public Schools, AR.
This curriculum guide is designed for group instruction of secondary agricultural education students enrolled in one or two semester-long courses in agricultural metal working. The guide presents units of study in the following areas: (1) oxyacetylene welding, (2) arc welding, (3) sheet metal, (4) blueprint reading for welders and (5) job…
75 FR 22770 - Gary E. Hall and Rita Hall; Notice of Availability of Environmental Assessment
Federal Register 2010, 2011, 2012, 2013, 2014
2010-04-30
... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Gary E. Hall and Rita Hall; Notice of Availability of Environmental Assessment April 22, 2010. In accordance with the National Environmental Policy Act of 1969, as amended,...
Charge carrier coherence and Hall effect in organic semiconductors
Yi, H. T.; Gartstein, Y. N.; Podzorov, V.
2016-01-01
Hall effect measurements are important for elucidating the fundamental charge transport mechanisms and intrinsic mobility in organic semiconductors. However, Hall effect studies frequently reveal an unconventional behavior that cannot be readily explained with the simple band-semiconductor Hall effect model. Here, we develop an analytical model of Hall effect in organic field-effect transistors in a regime of coexisting band and hopping carriers. The model, which is supported by the experiments, is based on a partial Hall voltage compensation effect, occurring because hopping carriers respond to the transverse Hall electric field and drift in the direction opposite to the Lorentz force acting on band carriers. We show that this can lead in particular to an underdeveloped Hall effect observed in organic semiconductors with substantial off-diagonal thermal disorder. Our model captures the main features of Hall effect in a variety of organic semiconductors and provides an analytical description of Hall mobility, carrier density and carrier coherence factor. PMID:27025354
ERIC Educational Resources Information Center
Brill, Winston J.
1981-01-01
Elucidates strategies for applying microbiological techniques to traditional agricultural practices. Discusses the manipulation of microorganisms that live with plants and also the problems involved in the introduction of new genes into crop plants by recombinant DNA methods. (CS)
Technology Transfer Automated Retrieval System (TEKTRAN)
The four geophysical methods predominantly used for agricultural purposes are resistivity, electromagnetic induction, ground penetrating radar (GPR), and time domain reflectometry (TDR). Resistivity and electromagnetic induction methods are typically employed to map lateral variations of apparent so...
Theory of the phonon Hall effect in paramagnetic dielectrics.
Sheng, L; Sheng, D N; Ting, C S
2006-04-21
Based upon Raman spin-lattice interaction, we propose a theoretical model for the phonon Hall effect in paramagnetic dielectrics, which was discovered recently in an experiment [C. Strohm, G. L. J. A. Rikken, and P. Wyder, Phys. Rev. Lett. 95, 155901 (2005).]. The phonon Hall effect is revealed to be a phonon analogue to the anomalous Hall effect in electron systems. The thermal Hall conductivity is calculated by using the Kubo formula. Our theory reproduces the essential experimental features of the phonon Hall effect, including the sign, magnitude, and linear magnetic field dependence of the thermal Hall conductivity.
Theory of Nematic Fractional Quantum Hall States
NASA Astrophysics Data System (ADS)
You, Yizhi; Cho, Gil Young; Fradkin, Eduardo
2014-10-01
We derive an effective field theory for the isotropic-nematic quantum phase transition of fractional quantum Hall states. We demonstrate that for a system with an isotropic background the low-energy effective theory of the nematic order parameter has z =2 dynamical scaling exponent, due to a Berry phase term of the order parameter, which is related to the nondissipative Hall viscosity. Employing the composite fermion theory with a quadrupolar interaction between electrons, we show that a sufficiently attractive quadrupolar interaction triggers a phase transition from the isotropic fractional quantum Hall fluid into a nematic fractional quantum Hall phase. By investigating the spectrum of collective excitations, we demonstrate that the mass gap of the Girvin-MacDonald-Platzman mode collapses at the isotropic-nematic quantum phase transition. On the other hand, Laughlin quasiparticles and the Kohn collective mode remain gapped at this quantum phase transition, and Kohn's theorem is satisfied. The leading couplings between the nematic order parameter and the gauge fields include a term of the same form as the Wen-Zee term. A disclination of the nematic order parameter carries an unquantized electric charge. We also discuss the relation between nematic degrees of freedom and the geometrical response of the fractional quantum Hall fluid.
Extrinsic spin Hall effect in graphene
NASA Astrophysics Data System (ADS)
Rappoport, Tatiana
The intrinsic spin-orbit coupling in graphene is extremely weak, making it a promising spin conductor for spintronic devices. In addition, many applications also require the generation of spin currents in graphene. Theoretical predictions and recent experimental results suggest one can engineer the spin Hall effect in graphene by greatly enhancing the spin-orbit coupling in the vicinity of an impurity. The extrinsic spin Hall effect then results from the spin-dependent skew scattering of electrons by impurities in the presence of spin-orbit interaction. This effect can be used to efficiently convert charge currents into spin-polarized currents. I will discuss recent experimental results on spin Hall effect in graphene decorated with adatoms and metallic cluster and show that a large spin Hall effect can appear due to skew scattering. While this spin-orbit coupling is small if compared with what it is found in metals, the effect is strongly enhanced in the presence of resonant scattering, giving rise to robust spin Hall angles. I will present our single impurity scattering calculations done with exact partial-wave expansions and complement the analysis with numerical results from a novel real-space implementation of the Kubo formalism for tight-binding Hamiltonians. The author acknowledges the Brazilian agencies CNPq, CAPES, FAPERJ and INCT de Nanoestruturas de Carbono for financial support.
Reed, Kathlyn L
2005-01-01
Herbert James Hall, MD (1870-1923), was a pioneer in the systematic and organized study of occupation as therapy for persons with nervous and mental disorders that he called the "work cure." He began his work in 1904 during the early years of the Arts and Crafts Movement in the United States. His primary interest was the disorder neurasthenia, a condition with many symptoms including chronic fatigue, stress, and inability to work or perform everyday tasks. The prevailing treatment of the day was absolute bed rest known as the "rest cure." Hall believed that neurasthenia was not caused by overwork but by faulty living habits that could be corrected through an ordered life schedule and selected occupations. He identified several principles of therapy that are still used today including graded activity and energy conservation. Dr. Adolph Meyer credits Hall for organizing the ideas on the therapeutic use of occupation (Meyer, 1922). Hall also provided the name American Occupational Therapy Association for the professional organization and served as the fourth president. For his many contributions to the profession Hall deserves to be recognized as a major contributor to the development and organization of occupational therapy. PMID:23927746
Piezo Voltage Controlled Planar Hall Effect Devices
Zhang, Bao; Meng, Kang-Kang; Yang, Mei-Yin; Edmonds, K. W.; Zhang, Hao; Cai, Kai-Ming; Sheng, Yu; Zhang, Nan; Ji, Yang; Zhao, Jian-Hua; Zheng, Hou-Zhi; Wang, Kai-You
2016-01-01
The electrical control of the magnetization switching in ferromagnets is highly desired for future spintronic applications. Here we report on hybrid piezoelectric (PZT)/ferromagnetic (Co2FeAl) devices in which the planar Hall voltage in the ferromagnetic layer is tuned solely by piezo voltages. The change of planar Hall voltage is associated with magnetization switching through 90° in the plane under piezo voltages. Room temperature magnetic NOT and NOR gates are demonstrated based on the piezo voltage controlled Co2FeAl planar Hall effect devices without the external magnetic field. Our demonstration may lead to the realization of both information storage and processing using ferromagnetic materials. PMID:27329068
Geometric Adiabatic Transport in Quantum Hall States.
Klevtsov, S; Wiegmann, P
2015-08-21
We argue that in addition to the Hall conductance and the nondissipative component of the viscous tensor, there exists a third independent transport coefficient, which is precisely quantized. It takes constant values along quantum Hall plateaus. We show that the new coefficient is the Chern number of a vector bundle over moduli space of surfaces of genus 2 or higher and therefore cannot change continuously along the plateau. As such, it does not transpire on a sphere or a torus. In the linear response theory, this coefficient determines intensive forces exerted on electronic fluid by adiabatic deformations of geometry and represents the effect of the gravitational anomaly. We also present the method of computing the transport coefficients for quantum Hall states. PMID:26340197
Geometric Adiabatic Transport in Quantum Hall States.
Klevtsov, S; Wiegmann, P
2015-08-21
We argue that in addition to the Hall conductance and the nondissipative component of the viscous tensor, there exists a third independent transport coefficient, which is precisely quantized. It takes constant values along quantum Hall plateaus. We show that the new coefficient is the Chern number of a vector bundle over moduli space of surfaces of genus 2 or higher and therefore cannot change continuously along the plateau. As such, it does not transpire on a sphere or a torus. In the linear response theory, this coefficient determines intensive forces exerted on electronic fluid by adiabatic deformations of geometry and represents the effect of the gravitational anomaly. We also present the method of computing the transport coefficients for quantum Hall states.
Logarithmic correlations in quantum Hall plateau transitions
NASA Astrophysics Data System (ADS)
Vasseur, Romain
2015-07-01
The critical behavior of quantum Hall transitions in two-dimensional disordered electronic systems can be described by a class of complicated, nonunitary conformal field theories with logarithmic correlations. The nature and the physical origin of these logarithmic correlation functions remain, however, mysterious. Using the replica trick and the underlying symmetries of these quantum critical points, we show here how to construct nonperturbatively disorder-averaged observables in terms of Green's functions that scale logarithmically at criticality. In the case of the spin quantum Hall transition, which may occur in disordered superconductors with spin-rotation symmetry and broken time reversal invariance, we argue that our results are compatible with an alternative approach based on supersymmetry. The generalization to the integer quantum Hall plateau transition is also discussed.
Piezo Voltage Controlled Planar Hall Effect Devices.
Zhang, Bao; Meng, Kang-Kang; Yang, Mei-Yin; Edmonds, K W; Zhang, Hao; Cai, Kai-Ming; Sheng, Yu; Zhang, Nan; Ji, Yang; Zhao, Jian-Hua; Zheng, Hou-Zhi; Wang, Kai-You
2016-01-01
The electrical control of the magnetization switching in ferromagnets is highly desired for future spintronic applications. Here we report on hybrid piezoelectric (PZT)/ferromagnetic (Co2FeAl) devices in which the planar Hall voltage in the ferromagnetic layer is tuned solely by piezo voltages. The change of planar Hall voltage is associated with magnetization switching through 90° in the plane under piezo voltages. Room temperature magnetic NOT and NOR gates are demonstrated based on the piezo voltage controlled Co2FeAl planar Hall effect devices without the external magnetic field. Our demonstration may lead to the realization of both information storage and processing using ferromagnetic materials. PMID:27329068
Spin Hall effect in doped semiconductor structures.
Tse, Wang-Kong; Das Sarma, S
2006-02-10
In this Letter we present a microscopic theory of the extrinsic spin Hall effect based on the diagrammatic perturbation theory. Side-jump and skew-scattering contributions are explicitly taken into account to calculate the spin Hall conductivity, and we show that their effects scale as sigma(xy)SJ/sigma(xy)SS approximately (h/tau)/epsilonF, with tau being the transport relaxation time. Motivated by recent experimental work we apply our theory to n- and p-doped 3D and 2D GaAs structures, obtaining sigma(s)/sigma(c) approximately 10(-3)-10(-4), where sigma(s(c)) is the spin Hall (charge) conductivity, which is in reasonable agreement with the recent experimental results of Kato et al. [Science 306, 1910 (2004)] in n-doped 3D GaAs system.
Extrinsic spin Hall effect from first principles.
Gradhand, Martin; Fedorov, Dmitry V; Zahn, Peter; Mertig, Ingrid
2010-05-01
We present an ab initio description of the spin Hall effect in metals. Our approach is based on density functional theory in the framework of a fully relativistic Korringa-Kohn-Rostoker method and the solution of a linearized Boltzmann equation including the scattering-in term (vertex corrections). The skew scattering mechanism at substitutional impurities is considered. Spin-orbit coupling in the host as well as at the impurity atom and the influence of spin-flip processes are fully taken into account. A sign change of the spin Hall effect in Cu and Au hosts is obtained as a function of the impurity atom, and even light elements like Li can cause a strong effect. It is shown that the gigantic spin Hall effect in Au can be caused by skew scattering at C and N impurities which are typical contaminations in a vacuum chamber.
Spin Hall Effect in Doped Semiconductor Structures
NASA Astrophysics Data System (ADS)
Tse, Wang-Kong; Das Sarma, Sankar
2006-03-01
We present a microscopic theory of the extrinsic spin Hall effect based on the diagrammatic perturbation theory. Side-jump (SJ) and skew-scattering (SS) contributions are explicitly taken into account to calculate the spin Hall conductivity, and we show their effects scale as σxy^SJ/σxy^SS ˜(/τ)/ɛF, where τ being the transport relaxation time. Motivated by recent experimental work we apply our theory to n-doped and p-doped 3D and 2D GaAs structures, obtaining analytical formulas for the SJ and SS contributions. Moreover, the ratio of the spin Hall conductivity to longitudinal conductivity is found as σs/σc˜10-3-10-4, in reasonable agreement with the recent experimental results of Kato et al. [Science 306, 1910 (2004)] in n-doped 3D GaAs system.
Extrinsic Spin Hall Effect from First Principles
NASA Astrophysics Data System (ADS)
Gradhand, Martin; Fedorov, Dmitry V.; Zahn, Peter; Mertig, Ingrid
2010-05-01
We present an ab initio description of the spin Hall effect in metals. Our approach is based on density functional theory in the framework of a fully relativistic Korringa-Kohn-Rostoker method and the solution of a linearized Boltzmann equation including the scattering-in term (vertex corrections). The skew scattering mechanism at substitutional impurities is considered. Spin-orbit coupling in the host as well as at the impurity atom and the influence of spin-flip processes are fully taken into account. A sign change of the spin Hall effect in Cu and Au hosts is obtained as a function of the impurity atom, and even light elements like Li can cause a strong effect. It is shown that the gigantic spin Hall effect in Au can be caused by skew scattering at C and N impurities which are typical contaminations in a vacuum chamber.
Spin Hall Effect in Doped Semiconductor Structures
NASA Astrophysics Data System (ADS)
Tse, Wang-Kong; Das Sarma, S.
2006-02-01
In this Letter we present a microscopic theory of the extrinsic spin Hall effect based on the diagrammatic perturbation theory. Side-jump and skew-scattering contributions are explicitly taken into account to calculate the spin Hall conductivity, and we show that their effects scale as σxySJ/σxySS˜(ℏ/τ)/ɛF, with τ being the transport relaxation time. Motivated by recent experimental work we apply our theory to n- and p-doped 3D and 2D GaAs structures, obtaining σs/σc˜10-3-10-4, where σs(c) is the spin Hall (charge) conductivity, which is in reasonable agreement with the recent experimental results of Kato et al. [Science 306, 1910 (2004)]SCIEAS0036-807510.1126/science.1105514 in n-doped 3D GaAs system.
Observation of intrinsic inverse spin Hall effect.
Werake, Lalani K; Ruzicka, Brian A; Zhao, Hui
2011-03-11
We report observation of intrinsic inverse spin Hall effect in undoped GaAs multiple quantum wells with a sample temperature of 10 K. A transient ballistic pure spin current is injected by a pair of laser pulses through quantum interference. By time resolving the dynamics of the pure spin current, the momentum relaxation time is deduced, which sets the lower limit of the scattering time between electrons and holes. The transverse charge current generated by the pure spin current via the inverse spin Hall effect is simultaneously resolved. We find that the charge current is generated well before the first electron-hole scattering event. Generation of the transverse current in the scattering-free ballistic transport regime provides unambiguous evidence for the intrinsic inverse spin Hall effect. PMID:21469830
Graphene-based Hall Sensors for direct magnetic imaging by using Scanning Hall Probe Microscope
NASA Astrophysics Data System (ADS)
Sonusen, Selda; Aksoy, Seda; Dede, Munir; Oral, Ahmet
2013-03-01
Graphene has been attracting great interest due to its unique electronic and mechanical properties for both fundamental and experimental studies since 2004. Graphene is a promising material for many applications in high speed electronic and spintronic devices as well as sensors. Its high mobility makes graphene a good candidate for magnetic imaging in Scanning Hall Probe Microscope (SHPM). Hall probes are used to scan the magnetic samples to image magnetic domains in SHPM. In this work, single layer graphene produced by chemical vapor deposition technique is used to fabricate Hall sensors by optical and the e-beam lithography with sizes from 500 nm to a few micrometers. The Hall crosses are characterized by Raman mapping to make sure that they are made of a single layer graphene. The Graphene Hall Sensors noise spectra is measured as a function of different bias currents and carrier concentrations at 300 K, 77 K and 4.24K. The imaging performance of the Hall sensor will be demonstrated at different temperatures by imaging a garnet crystal using a Low Temperature Scanning Hall Probe Microscope (LT-SHPM).
Shielding consideration for the SSCL experimental halls
Bull, J.; Coyne, J.; Mokhov, N.; Stapleton, G.
1994-03-01
The Superconducting Super Collider which is being designed and built in Waxahachie, Texas consists Of series of proton accelerators, culminating in a 20 Te proton on proton collider. The collider will be in a tunnel which will be 87 km in circumference and. on average about 30 meters underground. The present design calls for two large interaction halls on the east side of the ring. The shielding for these halls is being designed for an interaction rate of 10{sup 9} Hz or 10{sup 16} interactions per year, based on 10{sup 7} seconds per operational year. SSC guidelines require that the shielding be designed to meet the criterion of 1mSv per year for open areas off site 2mSv per year for open areas on site, and 2mSv per year for controlled areas. Only radiation workers will be routinely allowed to work in controlled areas. It should be pointed that there is a potential for an accidental full beam loss in either of the experimental halls, and this event would consist of the loss of the full circulating beam up to 4 {times} 10{sup 14} protons. With the present design. the calculated dose equivalent for this event is about 10% of the annual dose equivalent for the normal p-p interactions, so that die accident condition does not control the shielding. If, for instance, local shielding within the experimental hall is introduced into the calculations, this could change. The shielding requirements presented here are controlled by the normal p-p interactions. Three important questions were addressed in the present calculations. They are (1) the thickness of the roof over the experimental halls, (2) the configuration of the shafts and adits which give access to the halls, and (3) the problem of ground water and air activation.
Interior view of central hall from bedroom 2 showing linen ...
Interior view of central hall from bedroom 2 showing linen dresser, facing southwest. - Albrook Air Force Station, Non-Commissioned Officers' Duplex, East side of Hall Street, Balboa, Former Panama Canal Zone, CZ
24. BEDROOM #1 INTERIOR SHOWING OPEN DOOR TO HALL WITH ...
24. BEDROOM #1 INTERIOR SHOWING OPEN DOOR TO HALL WITH HALL LINEN CLOSETS VISIBLE IN BACKGROUND, AND PARTIALLY OPEN DOOR TO CLOSET. VIEW TO EAST. - Big Creek Hydroelectric System, Powerhouse 8, Operator Cottage, Big Creek, Big Creek, Fresno County, CA
Contextual view of ILWU Hall, facing southsouthwest, with ocean bank ...
Contextual view of ILWU Hall, facing south-southwest, with ocean bank visible in the background - International Longshoremen's & Warehousemen's Union Hall, Naval Civil Engineering Laboratory, Port Hueneme Road, Port Hueneme, Ventura County, CA
Contextual view of ILWU Hall, facing northwest with commercial port ...
Contextual view of ILWU Hall, facing northwest with commercial port buildings visible in the background - International Longshoremen's & Warehousemen's Union Hall, Naval Civil Engineering Laboratory, Port Hueneme Road, Port Hueneme, Ventura County, CA
Contextual view of ILWU Hall, facing east, with the city ...
Contextual view of ILWU Hall, facing east, with the city of Port Hueneme visible in the background - International Longshoremen's & Warehousemen's Union Hall, Naval Civil Engineering Laboratory, Port Hueneme Road, Port Hueneme, Ventura County, CA
Interior detail of platform in main hall, with desk, flag, ...
Interior detail of platform in main hall, with desk, flag, and banners, facing south - International Longshoremen's & Warehousemen's Union Hall, Naval Civil Engineering Laboratory, Port Hueneme Road, Port Hueneme, Ventura County, CA
Improved Readout For Micromagnet/Hall-Effect Memories
NASA Technical Reports Server (NTRS)
Wu, Jiin-Chuan; Stadler, Henry L.; Katti, Romney R.
1993-01-01
Two improved readout circuits for micromagnet/Hall-effect random-access memories designed to eliminate current shunts introducing errors into outputs of older readout circuits. Incorporate additional switching transistors to isolate Hall sensors as needed.
9. Historic American Buildings Survey, BINGHAMTON CITY HALL, PHOTOCOPY OF ...
9. Historic American Buildings Survey, BINGHAMTON CITY HALL, PHOTOCOPY OF ORIGINAL COMPETITION DRAWING (GENERAL PERSPECTIVE) - 1896 FROM THE OFFICE OF THE CITY ENGINEER, BINGHAMTON, NEW YORK. - Binghamton City Hall, Collier Street, Binghamton, Broome County, NY
10. Historic American Buildings Survey, BINGHAMTON CITY HALL, PHOTOCOPY OF ...
10. Historic American Buildings Survey, BINGHAMTON CITY HALL, PHOTOCOPY OF ORIGINAL COMPETITION DRAWING OF A LONGITUDINAL SECTION - 1896 FROM THE OFFICE OF THE CITY ENGINEER, BINGHAMTON, NEW YORK. - Binghamton City Hall, Collier Street, Binghamton, Broome County, NY
13. Historic American Buildings Survey, BINGHAMTON CITY HALL, PHOTOCOPY OF ...
13. Historic American Buildings Survey, BINGHAMTON CITY HALL, PHOTOCOPY OF ORIGINAL COMPETITION DRAWING OF FIRST FLOOR PLAN - 1896 FROM THE OFFICE OF THE CITY ENGINEER, BINGHAMTON, NEW YORK. - Binghamton City Hall, Collier Street, Binghamton, Broome County, NY
68. TURBINE HALL, LOOKING DOWN FROM THE CONTROL ROOM INTO ...
68. TURBINE HALL, LOOKING DOWN FROM THE CONTROL ROOM INTO TURBINE HALL AT UNITS 3, 5, AND 2) - Delaware County Electric Company, Chester Station, Delaware River at South end of Ward Street, Chester, Delaware County, PA
Quasihole condensates in quantum Hall liquids
Suorsa, J.; Viefers, S.; Hansson, T. H.
2011-06-15
We develop a formalism to describe quasihole condensates in quantum Hall liquids and thereby extend the conformal field theory approach to the full hierarchy of spin-polarized Abelian states and to several classes of non-Abelian hierarchical states. Most previously proposed spin-polarized quantum Hall wave functions appear as special cases. In this paper we explain the physical motivations for the approach, and exemplify it by explicitly constructing the level-two quasihole condensate state at filling fraction 2/3, and the two level-three states at 5/13 and 5/7 which are built from combinations of quasielectron and quasihole condensates.
Unconventional integer quantum Hall effect in graphene.
Gusynin, V P; Sharapov, S G
2005-09-30
Monolayer graphite films, or graphene, have quasiparticle excitations that can be described by (2+1)-dimensional Dirac theory. We demonstrate that this produces an unconventional form of the quantized Hall conductivity sigma(xy) = -(2e2/h)(2n+1) with n = 0, 1, ..., which notably distinguishes graphene from other materials where the integer quantum Hall effect was observed. This unconventional quantization is caused by the quantum anomaly of the n=0 Landau level and was discovered in recent experiments on ultrathin graphite films.
Spin Hall magnetoresistance in a canted ferrimagnet
NASA Astrophysics Data System (ADS)
Ganzhorn, Kathrin; Barker, Joseph; Schlitz, Richard; Piot, Benjamin A.; Ollefs, Katharina; Guillou, Francois; Wilhelm, Fabrice; Rogalev, Andrei; Opel, Matthias; Althammer, Matthias; Geprägs, Stephan; Huebl, Hans; Gross, Rudolf; Bauer, Gerrit E. W.; Goennenwein, Sebastian T. B.
2016-09-01
We study the spin Hall magnetoresistance effect in ferrimagnet/normal metal bilayers, comparing the response in collinear and canted magnetic phases. In the collinear magnetic phase, in which the sublattice magnetic moments are all aligned along the same axis, we observe the conventional spin Hall magnetoresistance. In contrast, in the canted phase, the magnetoresistance changes sign. Using atomistic spin simulations and x-ray absorption experiments, we can understand these observations in terms of the magnetic field and temperature dependent orientation of magnetic moments on different magnetic sublattices. This enables a magnetotransport based investigation of noncollinear magnetic textures.
Inverse spin Hall effect by spin injection
NASA Astrophysics Data System (ADS)
Liu, S. Y.; Horing, Norman J. M.; Lei, X. L.
2007-09-01
Motivated by a recent experiment [S. O. Valenzuela and M. Tinkham, Nature (London) 442, 176 (2006)], the authors present a quantitative microscopic theory to investigate the inverse spin-Hall effect with spin injection into aluminum considering both intrinsic and extrinsic spin-orbit couplings using the orthogonalized-plane-wave method. Their theoretical results are in good agreement with the experimental data. It is also clear that the magnitude of the anomalous Hall resistivity is mainly due to contributions from extrinsic skew scattering.
Prototype dining hall energy efficiency study
Mazzucchi, R.P.; Bailey, S.A.; Zimmerman, P.W.
1988-06-01
The energy consumption of food service facilities is among the highest of any commercial building type, owing to the special requirements for food preparation, sanitation, and ventilation. Consequently, the US Air Force Engineering and Services Center (AFESC) contracted with Pacific Northwest Laboratory (PNL) to collect and analyze end-use energy consumption data for a prototypical dining hall and make specific recommendations on cost-effective energy conservation options. This information will be used to establish or update criteria for dining hall designs and retrofits as appropriate. 6 refs., 21 figs., 23 tabs.
New type of magnetization equipment using a commercial Hall sensor
NASA Astrophysics Data System (ADS)
Nishioka, T.; Sato, N. K.
2004-05-01
We have developed a new method of the magnetization measurement using a commercial Hall sensor (Hall magnetometer), which enables us to measure the static magnetization very easily at temperatures as low as about 0.1 K and under pressure. We describe specifications of the Hall magnetometer, and show results of the magnetization measurement for UGe 2 as an example.
Destruction of the Fractional Quantum Hall Effect by Disorder
DOE R&D Accomplishments Database
Laughlin, R. B.
1985-07-01
It is suggested that Hall steps in the fractional quantum Hall effect are physically similar to those in the ordinary quantum Hall effect. This proposition leads to a simple scaling diagram containing a new type of fixed point, which is identified with the destruction of the fractional states by disorder. 15 refs., 3 figs.
Effects of Various Residence Hall Administrative Structures on Students
ERIC Educational Resources Information Center
Gifford, Brian M.
1974-01-01
This study was designed to determine the effect of three types of residence hall administrative structures on students' perceptions of their environment, residence hall dropout rate, students' grade point averages, noise level, and residence hall damage at the University of Missouri - Columbia campus. (Author)
Improved Hall-Effect Sensors For Magnetic Memories
NASA Technical Reports Server (NTRS)
Wu, Jiin-Chuan; Stadler, Henry L.; Katti, Romney R.; Chen, Y. C.; Bhattacharya, Pallab K.
1993-01-01
High-electron-mobility sensor films deposited on superlattice buffer (strain) layers. Improved Hall-effect sensors offer combination of adequate response and high speed needed for use in micromagnet/Hall-effect random-access memories. Hall-effect material chosen for use in sensors is InAs.
The Reference Function in a Residence Hall Library.
ERIC Educational Resources Information Center
Krupp, Robert Allen
This two-part paper based on experience at the University of Michigan includes a discussion of the potential reference function of a residence hall library in a university setting and a bibliography of over 100 suggested reference tools for residence hall libraries. The residence hall library is presented as a place where students should be able…
Parametric Investigations of Non-Conventional Hall Thruster
Raitses, Y.; Fisch, N.J.
2001-01-12
Hall thrusters might better scale to low power with non-conventional geometry. A 9 cm cylindrical, ceramic-channel, Hall thruster with a cusp-type magnetic field distribution has been investigated. It exhibits discharge characteristics similar to conventional coaxial Hall thrusters, but does not expose as much channel surface. Significantly, its operation is not accompanied by large amplitude discharge low frequency oscillations.
ERIC Educational Resources Information Center
Postance, Jim
1998-01-01
The extinction of farm animals and crops is rarely brought up during discussions of endangered species and biodiversity; however, the loss of diversity in crops and livestock threatens the sustainability of agriculture. Presents three activities: (1) "The Colors of Diversity"; (2) "Biodiversity among Animals"; and (3) "Heirloom Plants." Discusses…
ERIC Educational Resources Information Center
STEVENS, GLENN Z.
FEDERAL LEGISLATION HAS PROVIDED FOR PUBLIC PROGRAMS OF OCCUPATIONAL AGRICULTURE EDUCATION IN LAND GRANT COLLEGES AND UNIVERSITIES, LOCAL SCHOOL DISTRICTS, AND MANPOWER DEVELOPMENT PROGRAMS. PROGRAM OBJECTIVES SHOULD BE TO DEVELOP KNOWLEDGE AND SKILLS, PROVIDE OCCUPATIONAL GUIDANCE AND PLACEMENT, AND DEVELOP ABILITIES IN HUMAN RELATIONS AND…
ERIC Educational Resources Information Center
FARQUHAR, R.N.
AUSTRALIAN AGRICULTURAL EXTENSION HAS LONG EMPHASIZED TECHNICAL ADVISORY SERVICE AT THE EXPENSE OF THE SOCIOECONOMIC ASPECTS OF FARM PRODUCTION AND FARM LIFE. ONLY IN TASMANIA HAS FARM MANAGEMENT BEEN STRESSED. DEMANDS FOR THE WHOLE-FARM APPROACH HAVE PRODUCED A TREND TOWARD GENERALISM FOR DISTRICT OFFICERS IN MOST STATES. THE FEDERAL GOVERNMENT,…
Inertial-Hall effect: the influence of rotation on the Hall conductivity
NASA Astrophysics Data System (ADS)
Brandão, Julio E.; Moraes, F.; Cunha, M. M.; Lima, Jonas R. F.; Filgueiras, C.
Inertial effects play an important role in classical mechanics but have been largely overlooked in quantum mechanics. Nevertheless, the analogy between inertial forces on mass particles and electromagnetic forces on charged particles is not new. In this paper, we consider a rotating non-interacting planar two-dimensional electron gas with a perpendicular uniform magnetic field and investigate the effects of the rotation in the Hall conductivity. The rotation introduces a shift and a split in the Landau levels. As a consequence of the break of the degeneracy, the counting of the states fully occupied below the Fermi energy increases, tuning the Hall quantization steps. The rotation also changes the quantum Hall plateau widths. Additionally, we find the Hall quantization steps as a function of rotation at a fixed value of the magnetic field.
Guterding, Daniel; Jeschke, Harald O; Valentí, Roser
2016-01-01
Electronic states with non-trivial topology host a number of novel phenomena with potential for revolutionizing information technology. The quantum anomalous Hall effect provides spin-polarized dissipation-free transport of electrons, while the quantum spin Hall effect in combination with superconductivity has been proposed as the basis for realizing decoherence-free quantum computing. We introduce a new strategy for realizing these effects, namely by hole and electron doping kagome lattice Mott insulators through, for instance, chemical substitution. As an example, we apply this new approach to the natural mineral herbertsmithite. We prove the feasibility of the proposed modifications by performing ab-initio density functional theory calculations and demonstrate the occurrence of the predicted effects using realistic models. Our results herald a new family of quantum anomalous Hall and quantum spin Hall insulators at affordable energy/temperature scales based on kagome lattices of transition metal ions. PMID:27185665
NASA Astrophysics Data System (ADS)
Guterding, Daniel; Jeschke, Harald O.; Valentí, Roser
2016-05-01
Electronic states with non-trivial topology host a number of novel phenomena with potential for revolutionizing information technology. The quantum anomalous Hall effect provides spin-polarized dissipation-free transport of electrons, while the quantum spin Hall effect in combination with superconductivity has been proposed as the basis for realizing decoherence-free quantum computing. We introduce a new strategy for realizing these effects, namely by hole and electron doping kagome lattice Mott insulators through, for instance, chemical substitution. As an example, we apply this new approach to the natural mineral herbertsmithite. We prove the feasibility of the proposed modifications by performing ab-initio density functional theory calculations and demonstrate the occurrence of the predicted effects using realistic models. Our results herald a new family of quantum anomalous Hall and quantum spin Hall insulators at affordable energy/temperature scales based on kagome lattices of transition metal ions.
The magneto-Hall difference and the planar extraordinary Hall balance
NASA Astrophysics Data System (ADS)
Zhang, S. L.; Hesjedal, T.
2016-04-01
The extraordinary Hall balance (EHB) is a general device concept that harnesses the net extraordinary Hall effect (EHE) arising from two independent magnetic layers, which are electrically in parallel. Different EHB behavior can be achieved by tuning the strength and type of interlayer coupling, i.e., ferromagnetic or antiferromagnetic of varying strength, allowing for logic and memory applications. The physics of the EHE in such a multilayered systems, especially the interface-induced effect, will be discussed. A discrepancy between the magnetization and the Hall effect, called the magneto-Hall difference (MHD) is found, which is not expected in conventional EHE systems. By taking advantage of the MHD effect, and by optimizing the materials structure, magnetoresistance ratios in excess of 40,000% can be achieved at room-temperature. We present a new design, the planar EHB, which has the potential to achieve significantly larger magnetoresistance ratios.
Guterding, Daniel; Jeschke, Harald O.; Valentí, Roser
2016-01-01
Electronic states with non-trivial topology host a number of novel phenomena with potential for revolutionizing information technology. The quantum anomalous Hall effect provides spin-polarized dissipation-free transport of electrons, while the quantum spin Hall effect in combination with superconductivity has been proposed as the basis for realizing decoherence-free quantum computing. We introduce a new strategy for realizing these effects, namely by hole and electron doping kagome lattice Mott insulators through, for instance, chemical substitution. As an example, we apply this new approach to the natural mineral herbertsmithite. We prove the feasibility of the proposed modifications by performing ab-initio density functional theory calculations and demonstrate the occurrence of the predicted effects using realistic models. Our results herald a new family of quantum anomalous Hall and quantum spin Hall insulators at affordable energy/temperature scales based on kagome lattices of transition metal ions. PMID:27185665
Guterding, Daniel; Jeschke, Harald O; Valentí, Roser
2016-05-17
Electronic states with non-trivial topology host a number of novel phenomena with potential for revolutionizing information technology. The quantum anomalous Hall effect provides spin-polarized dissipation-free transport of electrons, while the quantum spin Hall effect in combination with superconductivity has been proposed as the basis for realizing decoherence-free quantum computing. We introduce a new strategy for realizing these effects, namely by hole and electron doping kagome lattice Mott insulators through, for instance, chemical substitution. As an example, we apply this new approach to the natural mineral herbertsmithite. We prove the feasibility of the proposed modifications by performing ab-initio density functional theory calculations and demonstrate the occurrence of the predicted effects using realistic models. Our results herald a new family of quantum anomalous Hall and quantum spin Hall insulators at affordable energy/temperature scales based on kagome lattices of transition metal ions.
18th Annual Residence Hall Construction Report
ERIC Educational Resources Information Center
Agron, Joe
2007-01-01
It is said that "home is where the heart is." Many colleges and universities are keeping that in mind as they continue to invest in building residential facilities to attract students to on-campus living. Residence hall construction at the nation's higher-education institutions remains strong, as the benefits to students, parents, and the college…
Residence Hall Furnishings Top 20 List.
ERIC Educational Resources Information Center
Tampke, Dale
1999-01-01
Provides advice on how to best meet the furniture needs of student residents now and in the future to ensure their privacy and value from the residence hall experience. Twenty tips are highlighted that include considering fire safety, upholstering, lifecycle costs, input from stakeholders, the Americans with Disabilities Act, comfort, lighting,…
A Small Modular Laboratory Hall Effect Thruster
NASA Astrophysics Data System (ADS)
Lee, Ty Davis
Electric propulsion technologies promise to revolutionize access to space, opening the door for mission concepts unfeasible by traditional propulsion methods alone. The Hall effect thruster is a relatively high thrust, moderate specific impulse electric propulsion device that belongs to the class of electrostatic thrusters. Hall effect thrusters benefit from an extensive flight history, and offer significant performance and cost advantages when compared to other forms of electric propulsion. Ongoing research on these devices includes the investigation of mechanisms that tend to decrease overall thruster efficiency, as well as the development of new techniques to extend operational lifetimes. This thesis is primarily concerned with the design and construction of a Small Modular Laboratory Hall Effect Thruster (SMLHET), and its operation on argon propellant gas. Particular attention was addressed at low-cost, modular design principles, that would facilitate simple replacement and modification of key thruster parts such as the magnetic circuit and discharge channel. This capability is intended to facilitate future studies of device physics such as anomalous electron transport and magnetic shielding of the channel walls, that have an impact on thruster performance and life. Preliminary results demonstrate SMLHET running on argon in a manner characteristic of Hall effect thrusters, additionally a power balance method was utilized to estimate thruster performance. It is expected that future thruster studies utilizing heavier though more expensive gases like xenon or krypton, will observe increased efficiency and stability.
ERIC Educational Resources Information Center
Torres, Mellie
2009-01-01
Situating herself on the cusp between life in her hometown of Newark, New Jersey, and her new world at Seton Hall University, Mellie Torres describes the painful awareness of a growing distance between herself, as the first to go to college, and her family. In so doing, she reveals the inherent losses of leaving home and the painful contrast…
Air Temperature in the Undulator Hall
Not Available
2010-12-07
Various analyses have been performed recently to estimate the performance of the air conditioning (HVAC) system planned for the Undulator Hall. This reports summarizes the results and provides an upgrade plan to be used if new requirements are needed in the future. The estimates predict that with the planned loads the tunnel air temperature will be well within the allowed tolerance during normal operation.
June 1992 Hall B collaboration meeting
Dennis, Lawrence
1992-06-01
The Hall B collaboration meeting at the CEBAF 1992 Summer Workshop consisted of technical and physics working group meetings, a special beam line devices working group meeting the first meeting of the membership committee, a technical representatives meeting and a full collaboration meeting. Highlights of these meetings are presented in this report.
Fractional Quantization of the Hall Effect
DOE R&D Accomplishments Database
Laughlin, R. B.
1984-02-27
The Fractional Quantum Hall Effect is caused by the condensation of a two-dimensional electron gas in a strong magnetic field into a new type of macroscopic ground state, the elementary excitations of which are fermions of charge 1/m, where m is an odd integer. A mathematical description is presented.
Multivariable scaling for the anomalous Hall effect.
Hou, Dazhi; Su, Gang; Tian, Yuan; Jin, Xiaofeng; Yang, Shengyuan A; Niu, Qian
2015-05-29
We derive a general scaling relation for the anomalous Hall effect in ferromagnetic metals involving multiple competing scattering mechanisms, described by a quadratic hypersurface in the space spanned by the partial resistivities. We also present experimental findings, which show strong deviation from previously found scaling forms when different scattering mechanisms compete in strength but can be nicely explained by our theory.
Town Hall on AGU Publishing Practices
NASA Astrophysics Data System (ADS)
Forlini, Victoria
2013-01-01
Representatives from AGU's leadership and Wiley fielded questions at a town hall during Fall Meeting that ranged from the pricing of AGU's digital library to the fate of AGU books to the role of the governance structure in approving the AGU-Wiley publications partnership.
Spin Hall effect on a noncommutative space
Ma Kai; Dulat, Sayipjamal
2011-07-15
We study the spin-orbital interaction and the spin Hall effect of an electron moving on a noncommutative space under the influence of a vector potential A(vector sign). On a noncommutative space, we find that the commutator between the vector potential A(vector sign) and the electric potential V{sub 1}(r(vector sign)) of the lattice induces a new term, which can be treated as an effective electric field, and the spin Hall conductivity obtains some correction. On a noncommutative space, the spin current and spin Hall conductivity have distinct values in different directions, and depend explicitly on the noncommutative parameter. Once this spin Hall conductivity in different directions can be measured experimentally with a high level of accuracy, the data can then be used to impose bounds on the value of the space noncommutativity parameter. We have also defined a new parameter, {sigma}={rho}{theta} ({rho} is the electron concentration, {theta} is the noncommutativity parameter), which can be measured experimentally. Our approach is based on the Foldy-Wouthuysen transformation, which gives a general Hamiltonian of a nonrelativistic electron moving on a noncommutative space.
Genetics Home Reference: Pallister-Hall syndrome
... in the brain called a hypothalamic hamartoma is characteristic of this disorder. In many cases, these growths do not cause any medical problems; however, some hypothalamic hamartomas lead to seizures or hormone abnormalities that can be life-threatening in infancy. Other features of Pallister-Hall ...
Soaring Food Prices Squeeze Dining Halls
ERIC Educational Resources Information Center
Hermes, JJ
2008-01-01
This article reports that students are likely to see a sharp increase in the cost of on-campus meal plans this fall, as rising food prices have sent some college food-service operations into deficits and have forced many to get creative with their fixed budgets. As the cost of food has soared, many dining halls have focused more on reducing…
Moderate positive spin Hall angle in uranium
Singh, Simranjeet; Anguera, Marta; Barco, Enrique del E-mail: cwmsch@rit.edu; Springell, Ross; Miller, Casey W. E-mail: cwmsch@rit.edu
2015-12-07
We report measurements of spin pumping and the inverse spin Hall effect in Ni{sub 80}Fe{sub 20}/uranium bilayers designed to study the efficiency of spin-charge interconversion in a super-heavy element. We employ broad-band ferromagnetic resonance on extended films to inject a spin current from the Ni{sub 80}Fe{sub 20} (permalloy) into the uranium layer, which is then converted into an electric field by the inverse spin Hall effect. Surprisingly, our results suggest a spin mixing conductance of order 2 × 10{sup 19} m{sup −2} and a positive spin Hall angle of 0.004, which are both merely comparable with those of several transition metals. These results thus support the idea that the electronic configuration may be at least as important as the atomic number in governing spin pumping across interfaces and subsequent spin Hall effects. In fact, given that both the magnitude and the sign are unexpected based on trends in d-electron systems, materials with unfilled f-electron orbitals may hold additional exploration avenues for spin physics.
FORT HALL SOURCE APPORTIONMENT STUDY (FINAL REPORT)
Air quality monitoring on the Fort Hall Indian Reservation has revealed numerous exceedances of the National Ambient Air Quality Standard (NAAQS) for 24-h averaged PM10 mass. Wind-directional analysis coupled with PM10 measurements have identified the FMC elemental phosphorus p...
Dust exposure in indoor climbing halls.
Weinbruch, Stephan; Dirsch, Thomas; Ebert, Martin; Hofmann, Heiko; Kandler, Konrad
2008-05-01
The use of hydrated magnesium carbonate hydroxide (magnesia alba) for drying the hands is a strong source for particulate matter in indoor climbing halls. Particle mass concentrations (PM10, PM2.5 and PM1) were measured with an optical particle counter in 9 indoor climbing halls and in 5 sports halls. Mean values for PM10 in indoor climbing halls are generally on the order of 200-500 microg m(-3). For periods of high activity, which last for several hours, PM10 values between 1000 and 4000 microg m(-3) were observed. PM(2.5) is on the order of 30-100 microg m(-3) and reaches values up to 500 microg m(-3), if many users are present. In sports halls, the mass concentrations are usually much lower (PM10 < 100 microg m(-3), PM2.5 < or = 20 microg m(-3)). However, for apparatus gymnastics (a sport in which magnesia alba is also used) similar dust concentrations as for indoor climbing were observed. The size distribution and the total particle number concentration (3.7 nm-10 microm electrical mobility diameter) were determined in one climbing hall by an electrical aerosol spectrometer. The highest number concentrations were between 8000 and 12 000 cm(-3), indicating that the use of magnesia alba is no strong source for ultrafine particles. Scanning electron microscopy and energy-dispersive X-ray microanalysis revealed that virtually all particles are hydrated magnesium carbonate hydroxide. In-situ experiments in an environmental scanning electron microscope showed that the particles do not dissolve at relative humidities up to 100%. Thus, it is concluded that solid particles of magnesia alba are airborne and have the potential to deposit in the human respiratory tract. The particle mass concentrations in indoor climbing halls are much higher than those reported for schools and reach, in many cases, levels which are observed for industrial occupations. The observed dust concentrations are below the current occupational exposure limits in Germany of 3 and 10 mg m(-3) for
Federal Register 2010, 2011, 2012, 2013, 2014
2010-01-05
... National Park Service Notice of Intent to Repatriate a Cultural Item: Seton Hall University Museum, Seton Hall University, South Orange, NJ AGENCY: National Park Service, Interior. ACTION: Notice. Notice is... University Museum, Seton Hall University, South Orange, NJ, that meets the definitions of ``sacred...
Long-wavelength corrections to Hall conductivity in fractional quantum Hall fluids
NASA Astrophysics Data System (ADS)
Yang, Bo; Haldane, F. D. M.
2013-03-01
Recent work by Hoyos and Son, then Bradlyn et al., has investigated the relation between the long-wavelength (O (q2)) corrections to the Hall conductivity σH (q) and the Hall viscosity of quantum Hall states. These works assume the presence of Galilean and rotational invariance. However, these are not generic symmetries of electrons in condensed matter. We identify translation and (2D) inversion symmetry as the only generic symmetries of an ``ideal'' quantum Hall liquid, as these are needed to guarantee the absence of any dissipationless ground state current density; then σH (q) = σH (- q) characterizes the dissipation less current that flows in response to a spatially-non-uniform electric field. We consider the general problem for fractional quantum Hall (FQH) states without Galilean or rotational invariance, when the guiding-center contribution to the Hall viscosity becomes a non-trivial tensor property related to an emergent geometry of the FQH state, (Bo Yang et,al (PRB 85,165318). Supported by DOE DE-SC0002140 and Agency for Science Technology and Research (A*STAR, Singapore).
NASA Astrophysics Data System (ADS)
Owerre, S. A.
2016-07-01
Quite recently, the magnon Hall effect of spin excitations has been observed experimentally on the kagome and pyrochlore lattices. The thermal Hall conductivity κxy changes sign as a function of magnetic field or temperature on the kagome lattice, and κxy changes sign upon reversing the sign of the magnetic field on the pyrochlore lattice. Motivated by these recent exciting experimental observations, we theoretically propose a simple realization of the magnon Hall effect in a two-band model on the honeycomb lattice. The magnon Hall effect of spin excitations arises in the usual way via the breaking of inversion symmetry of the lattice, however, by a next-nearest-neighbour Dzyaloshinsky-Moriya interaction. We find that κxy has a fixed sign for all parameter regimes considered. These results are in contrast to the Lieb, kagome, and pyrochlore lattices. We further show that the low-temperature dependence on the magnon Hall conductivity follows a T2 law, as opposed to the kagome and pyrochlore lattices. These results suggest an experimental procedure to measure thermal Hall conductivity within a class of 2D honeycomb quantum magnets and ultracold atoms trapped in a honeycomb optical lattice.
The Integer and Fractional Quantum Hall Effects.
NASA Astrophysics Data System (ADS)
Usher, Alan
Available from UMI in association with The British Library. Requires signed TDF. This thesis reports investigations of the electrical conductivity of two-dimensional electron systems in high magnetic fields. Studies of the activated longitudinal conductivity associated with the integer quantum Hall effect reveal a large enhancement of the electronic g-factor, caused by the electron-electron interaction. A similar enhancement is observed in the Landau level separation. The magnetic field dependences of both effects are influenced by sample disorder. The activation data are analysed using three models for the shape of the extended state regions of disorder -broadened Landau levels. Only a small fraction of the electrons are found to occupy extended states. Values of the minimum metallic conductivity of electrons in broadened Landau levels are sample- and electron concentration-dependent. The fractional quantum Hall effect is a property of electrons in an incompressible quantum fluid state. The highest quality samples with low electron concentrations exhibit the effect in the manner predicted by simple theories involving spinless electrons. However, the influence of spin becomes apparent at higher electron concentrations, and in tilted field experiments. The effects of disorder are evident in measurements of the quasiparticle energy gap associated with the fractional quantum Hall effect. The experimental gap energies reported in this thesis are considerably smaller than those of theoretical studies, and they tend to zero at a non-zero magnetic field threshold. Simple theories predict that the fractional quantum Hall effect occurs only at odd denominator fractional occupancies. This thesis reports the first observations of the even denominator fractional quantum Hall effect. Persistent photoconductivity is a useful tool for increasing the concentration of two-dimensional electrons in GaAs-AlGaAs heterojunctions. A new photodeexcitation effect is reported, and possible
Extrinsic spin Hall effect induced by iridium impurities in copper.
Niimi, Y; Morota, M; Wei, D H; Deranlot, C; Basletic, M; Hamzic, A; Fert, A; Otani, Y
2011-03-25
We study the extrinsic spin Hall effect induced by Ir impurities in Cu by injecting a pure spin current into a CuIr wire from a lateral spin valve structure. While no spin Hall effect is observed without Ir impurity, the spin Hall resistivity of CuIr increases linearly with the impurity concentration. The spin Hall angle of CuIr, (2.1±0.6)% throughout the concentration range between 1% and 12%, is practically independent of temperature. These results represent a clear example of predominant skew scattering extrinsic contribution to the spin Hall effect in a nonmagnetic alloy.
Extrinsic Spin Hall Effect Induced by Iridium Impurities in Copper
NASA Astrophysics Data System (ADS)
Niimi, Y.; Morota, M.; Wei, D. H.; Deranlot, C.; Basletic, M.; Hamzic, A.; Fert, A.; Otani, Y.
2011-03-01
We study the extrinsic spin Hall effect induced by Ir impurities in Cu by injecting a pure spin current into a CuIr wire from a lateral spin valve structure. While no spin Hall effect is observed without Ir impurity, the spin Hall resistivity of CuIr increases linearly with the impurity concentration. The spin Hall angle of CuIr, (2.1±0.6)% throughout the concentration range between 1% and 12%, is practically independent of temperature. These results represent a clear example of predominant skew scattering extrinsic contribution to the spin Hall effect in a nonmagnetic alloy.
Plasma relaxation and topological aspects in Hall magnetohydrodynamics
Shivamoggi, B. K.
2012-07-15
Parker's formulation of isotopological plasma relaxation process in magnetohydrodynamics (MHD) is extended to Hall MHD. The torsion coefficient {alpha} in the Hall MHD Beltrami condition turns out now to be proportional to the potential vorticity. The Hall MHD Beltrami condition becomes equivalent to the potential vorticity conservation equation in two-dimensional (2D) hydrodynamics if the Hall MHD Lagrange multiplier {beta} is taken to be proportional to the potential vorticity as well. The winding pattern of the magnetic field lines in Hall MHD then appears to evolve in the same way as potential vorticity lines in 2D hydrodynamics.
A Hall effect angle detector for solid-state NMR
NASA Astrophysics Data System (ADS)
Mamone, Salvatore; Dorsch, André; Johannessen, Ole G.; Naik, Manoj V.; Madhu, P. K.; Levitt, Malcolm H.
2008-01-01
We describe a new method for independent monitoring of the angle between the spinning axis and the magnetic field in solid-state NMR. A Hall effect magnetic flux sensor is fixed to the spinning housing, so that a change in the stator orientation leads to a change in the angle between the Hall plane and the static magnetic field. This leads to a change in the Hall voltage generated by the sensor when an electric current is passed through it. The Hall voltage may be measured externally by a precision voltmeter, allowing the spinning angle to be measured non-mechanically and independent of the NMR experiment. If the Hall sensor is mounted so that the magnetic field is approximately parallel to the Hall plane, the Hall voltage becomes highly sensitive to the stator orientation. The current angular accuracy is around 10 millidegrees. The precautions needed to achieve higher angular accuracy are described.
A Hall effect angle detector for solid-state NMR.
Mamone, Salvatore; Dorsch, André; Johannessen, Ole G; Naik, Manoj V; Madhu, P K; Levitt, Malcolm H
2008-01-01
We describe a new method for independent monitoring of the angle between the spinning axis and the magnetic field in solid-state NMR. A Hall effect magnetic flux sensor is fixed to the spinning housing, so that a change in the stator orientation leads to a change in the angle between the Hall plane and the static magnetic field. This leads to a change in the Hall voltage generated by the sensor when an electric current is passed through it. The Hall voltage may be measured externally by a precision voltmeter, allowing the spinning angle to be measured non-mechanically and independent of the NMR experiment. If the Hall sensor is mounted so that the magnetic field is approximately parallel to the Hall plane, the Hall voltage becomes highly sensitive to the stator orientation. The current angular accuracy is around 10 millidegrees. The precautions needed to achieve higher angular accuracy are described.
Room temperature scanning Hall probe microscopy using GaAs/AlGaAs and Bi micro-hall probes.
Sandhu, A; Masuda, H; Oral, A; Bending, S J; Yamada, A; Konagai, M
2002-05-01
A room temperature scanning Hall probe microscope system utilizing GaAs/AlGaAs and bismuth micro-Hall probes was used for magnetic imaging of ferromagnetic domain structures on the surfaces of crystalline thin film garnets and permanent magnets. The Bi micro-Hall probes had dimensions ranging between 0.25 and 2.8 microm2 and were fabricated using a combination of optical lithography and focused ion beam milling. The use of bismuth was found to overcome surface depletion effects associated with semiconducting micro-Hall probes. Our experiments demonstrated that Bi is a practical choice of material for fabricating sub-micron sized Hall sensors.
Diagnostics Systems for Permanent Hall Thrusters Development
NASA Astrophysics Data System (ADS)
Ferreira, Jose Leonardo; Soares Ferreira, Ivan; Santos, Jean; Miranda, Rodrigo; Possa, M. Gabriela
This work describes the development of Permanent Magnet Hall Effect Plasma Thruster (PHALL) and its diagnostic systems at The Plasma Physics Laboratory of University of Brasilia. The project consists on the construction and characterization of plasma propulsion engines based on the Hall Effect. Electric thrusters have been employed in over 220 successful space missions. Two types stand out: the Hall-Effect Thruster (HET) and the Gridded Ion Engine (GIE). The first, which we deal with in this project, has the advantage of greater simplicity of operation, a smaller weight for the propulsion subsystem and a longer shelf life. It can operate in two configurations: magnetic layer and anode layer, the difference between the two lying in the positioning of the anode inside the plasma channel. A Hall-Effect Thruster-HET is a type of plasma thruster in which the propellant gas is ionized and accelerated by a magneto hydrodynamic effect combined with electrostatic ion acceleration. So the essential operating principle of the HET is that it uses a J x B force and an electrostatic potential to accelerate ions up to high speeds. In a HET, the attractive negative charge is provided by electrons at the open end of the Thruster instead of a grid, as in the case of the electrostatic ion thrusters. A strong radial magnetic field is used to hold the electrons in place, with the combination of the magnetic field and the electrostatic potential force generating a fast circulating electron current, the Hall current, around the axis of the Thruster, mainly composed by drifting electrons in an ion plasma background. Only a slow axial drift towards the anode occurs. The main attractive features of the Hall-Effect Thruster are its simple design and operating principles. Most of the Hall-Effect Thrusters use electromagnet coils to produce the main magnetic field responsible for plasma generation and acceleration. In this paper we present a different new concept, a Permanent Magnet Hall
Hall scrambling on black hole horizons
NASA Astrophysics Data System (ADS)
Fischler, Willy; Kundu, Sandipan
2015-08-01
We explore the effect of the electrodynamics θ angle on the macroscopic properties of black hole horizons. Using only classical Einstein-Maxwell-Chern-Simons theory in (3 +1 ) dimensions, in the form of the membrane paradigm, we show that in the presence of the θ term, a black hole horizon behaves as a Hall conductor, for an observer hovering outside. We study how localized perturbations created on the stretched horizon scramble on the horizon by dropping a charged particle. We show that the θ angle affects the way perturbations scramble on the horizon, in particular, it introduces vortices without changing the scrambling time. This Hall scrambling of information is also expected to occur on cosmological horizons.
Sammons, Morgan T; Boucher, Andrew
2016-01-01
Presents an obituary for Judy Estes Hall, who passed away on November 24, 2015. Hall served as the Executive Officer of the National Register of Health Service Psychologists until her retirement in 2013. She is a recognized expert in the development of education and training standards for the profession of psychology, she also made significant contributions in the field of international psychology, where she was a renowned expert in cross-national credentialing and an advocate for commonality in licensing standards. She was the coauthor of one edited volume and author of more than 60 journal articles, book chapters, and professional publications. A passionate advocate for the advancement of women in psychology, a devoted mother and grandmother, a connoisseur of wine and international traveler extraordinaire, she touched the personal and professional lives of many. (PsycINFO Database Record
Sammons, Morgan T; Boucher, Andrew
2016-01-01
Presents an obituary for Judy Estes Hall, who passed away on November 24, 2015. Hall served as the Executive Officer of the National Register of Health Service Psychologists until her retirement in 2013. She is a recognized expert in the development of education and training standards for the profession of psychology, she also made significant contributions in the field of international psychology, where she was a renowned expert in cross-national credentialing and an advocate for commonality in licensing standards. She was the coauthor of one edited volume and author of more than 60 journal articles, book chapters, and professional publications. A passionate advocate for the advancement of women in psychology, a devoted mother and grandmother, a connoisseur of wine and international traveler extraordinaire, she touched the personal and professional lives of many. (PsycINFO Database Record PMID:27504582
Induced radioisotopes in a linac treatment hall.
Vega-Carrillo, Héctor René; de Leon-Martinez, Héctor Asael; Rivera-Perez, Esteban; Luis Benites-Rengifo, Jorge; Gallego, Eduardo; Lorente, Alfredo
2015-08-01
When linacs operate above 8MV an undesirable neutron field is produced whose spectrum has three main components: the direct spectrum due to those neutrons leaking out from the linac head, the scattered spectrum due to neutrons produced in the head that collides with the nuclei in the head losing energy and the third spectrum due to room-return effect. The third category of spectrum has mainly epithermal and thermal neutrons being constant at any location in the treatment hall. These neutrons induce activation in the linac components, the concrete walls and in the patient body. Here the induced radioisotopes have been identified in concrete samples located in the hall and in one of the wedges. The identification has been carried out using a gamma-ray spectrometer.
Three halls for music performance in Chile
NASA Astrophysics Data System (ADS)
Delannoy, Jaime; Heuffemann, Carolina; Ramirez, Daniel; Galvez, Fernando
2002-11-01
The primary purpose of this work was to investigate about the present acoustic conditions of used architectonic spaces in Santiago of Chile for orchestras of classic music performance. The studied halls were three: Aula Magna Universidad de Santiago, Teatro Municipal de Nunoa, and Teatro Baquedano. The used methodology was based on studies made by L. Beranek, M. Barron, among others, in concert halls worldwide. As it guides, for the measurement procedure, physical parameters RT, EDT, C50, C80, LF, BR, G, U50 were evaluated according to norm ISO 3382. On the other hand, it has been defined, to proposal way, a questionnaire of subjective valuation directed to musicians, specialized conductors, and listeners.
Anomalous Hall effect in Weyl superconductors
NASA Astrophysics Data System (ADS)
Bednik, G.; Zyuzin, A. A.; Burkov, A. A.
2016-08-01
We present a theory of the anomalous Hall effect in a topological Weyl superconductor with broken time reversal symmetry. Specifically, we consider a ferromagnetic Weyl metal with two Weyl nodes of opposite chirality near the Fermi energy. In the presence of inversion symmetry, such a metal experiences a weak-coupling Bardeen-Cooper-Schrieffer instability, with pairing of parity-related eigenstates. Due to the nonzero topological charge, carried by the Weyl nodes, such a superconductor is necessarily topologically nontrivial, with Majorana surface states coexisting with the Fermi arcs of the normal Weyl metal. We demonstrate that, surprisingly, the anomalous Hall conductivity of such a superconducting Weyl metal coincides with that of a nonsuperconducting one, under certain conditions, in spite of the nonconservation of charge in a superconductor. We relate this to the existence of an extra (nearly) conserved quantity in a Weyl metal, the chiral charge.
Hall magnetohydrodynamics: Conservation laws and Lyapunov stability
NASA Astrophysics Data System (ADS)
Holm, Darryl D.
1987-05-01
Hall electric fields produce circulating mass flow in confined ideal-fluid plasmas. The conservation laws, Hamiltonian structure, equilibrium state relations, and Lyapunov stability conditions are presented here for ideal Hall magnetohydrodynamics (HMHD) in two and three dimensions. The approach here is to use the remarkable array of nonlinear conservation laws for HMHD that follow from its Hamiltonian structure in order to construct explicit Lyapunov functionals for the HMHD equilibrium states. In this way, the Lyapunov stability analysis provides classes of HMHD equilibria that are stable and whose linearized initial-value problems are well posed (in the sense of possessing continuous dependence on initial conditions). Several examples are discussed in both two and three dimensions.
Vortex Physics in the Quantum Hall Bilayer
NASA Astrophysics Data System (ADS)
Fertig, H. A.; Murthy, Ganpathy
2013-06-01
There exists a strong analogy between the quantum Hall bilayer system at total filling factor ν = 1 and a thin film superfluid, in which the groundstate is described as a condensate of particle-hole pairs. The analogy draws support from experiments which display near dissipationless transport properties at low temperatures. However dissipation is always present at any accessible temperature, suggesting that in a proper description, unpaired vortex-like excitations must be present. The mechanism by which this happens remains poorly understood. A key difference between the quantum Hall bilayer and simpler thin-film superfluids is that the vortices, more properly called merons in the former context, are charged objects. We demonstrate that a model in which disorder induces merons in the groundstate, through coupling to this charge, can naturally explain many of the observed imperfect superfluid properties...
Geometry of fractional quantum Hall fluids
NASA Astrophysics Data System (ADS)
Cho, Gil Young; You, Yizhi; Fradkin, Eduardo
2014-09-01
We use the field theory description of the fractional quantum Hall states to derive the universal response of these topological fluids to shear deformations and curvature of their background geometry, i.e., the Hall viscosity, and the Wen-Zee term. To account for the coupling to the background geometry, we show that the concept of flux attachment needs to be modified and use it to derive the geometric responses from Chern-Simons theories. We show that the resulting composite particles minimally couple to the spin connection of the geometry. We derive a consistent theory of geometric responses from the Chern-Simons effective field theories and from parton constructions, and apply it to both Abelian and non-Abelian states.
Supercurrent in the quantum Hall regime
NASA Astrophysics Data System (ADS)
Wei, Ming-Tso; Amet, François; Ke, Chung-Ting; Borzenets, Ivan; Wang, Jiyingmei; Watanabe, Keji; Taniguchi, Takashi; Deacon, Russell; Yamamoto, Michihisa; Bomze, Yuriy; Tarucha, Seigo; Finkelstein, Gleb
Combining superconductivity and the quantum Hall (QH) effect is a promising route for creating new types of topological excitations. Despite this potential, signatures of superconductivity in the quantum Hall regime remain scarce, and a superconducting current through a QH weak link has so far eluded experimental observation. Here we demonstrate the existence of a novel type of Josephson coupling through a QH region at magnetic fields as high as 2 Tesla. The supercurrent is mediated by states encompassing QH edge channels, which are flowing on opposite sides of the sample. The edges are coupled together by the hybrid electron-hole modes at the interfaces between the QH region and the superconducting contacts. These chiral modes, which share some features with Majorana modes, are formed when electron and hole edge states are mixed by the superconductor.
Developments in the quantum Hall effect.
von Klitzing, Klaus
2005-09-15
The most important applications of the quantum Hall effect (QHE) are in the field of metrology. The observed quantization of the resistance is primarily used for the reproduction of the SI unit ohm, but is also important for high precision measurements of both the fine structure constant and the Planck constant. Some current QHE research areas include the analysis of new electron-electron correlation phenomena and the development of a more complete microscopic picture of this quantum effect. Recently, scanning force microscopy (SFM) of the potential distribution in QHE devices has been used to enhance the microscopic understanding of current flow in quantum Hall systems. This confirms the importance of the theoretically predicted stripes of compressible and incompressible electronic states close to the boundary of the QHE devices.
Hall drag and magnetodrag in graphene.
Song, Justin C W; Levitov, Leonid S
2013-09-20
Massless Dirac fermions in graphene at charge neutrality form a strongly interacting system in which both charged and neutral (energy) modes play an important role. These modes are essentially decoupled in the absence of a magnetic field, but become strongly coupled when the field is applied. We show that this regime is characterized by strong magnetodrag and Hall drag, originating from long-range energy currents and spatial temperature gradients. The energy-driven effects arise in a wide temperature range, and feature an unusually strong dependence on field and carrier density. We argue that this mechanism accounts for the recently observed giant magnetodrag and Hall drag occurring at classically weak fields. PMID:24093284
Fractional quantum Hall states of Rydberg polaritons
NASA Astrophysics Data System (ADS)
Maghrebi, Mohammad F.; Yao, Norman Y.; Hafezi, Mohammad; Pohl, Thomas; Firstenberg, Ofer; Gorshkov, Alexey V.
2015-03-01
We propose a scheme for realizing fractional quantum Hall states of light. In our scheme, photons of two polarizations are coupled to different atomic Rydberg states to form two flavors of Rydberg polaritons that behave as an effective spin. An array of optical cavity modes overlapping with the atomic cloud enables the realization of an effective spin-1 /2 lattice. We show that the dipolar interaction between such polaritons, inherited from the Rydberg states, can be exploited to create a flat, topological band for a single spin-flip excitation. At half filling, this gives rise to a photonic (or polaritonic) fractional Chern insulator—a lattice-based, fractional quantum Hall state of light.
Hall Thruster Satellite Communication Impact Analysis
NASA Astrophysics Data System (ADS)
Hallock, G. A.; Wiley, J. C.; Khanna, A.; Spencer, E. A.
1999-11-01
A critical issue which arises in the integration of Hall thruster technology for communication satellite stationkeeping is refraction of the microwave signals caused by the highly ionized plasma plume. This can cause pointing error, sidelobe degradation, and other changes to the antenna pattern. We have developed vector ray tracing codes, which track the trajectory, amplitude, phase, and polarization of a bundle of rays from the antenna reflector or feed. Shaped reflectors are used in modern satellites to tailor the antenna pattern to the desired receiving area. We are investigating the distortion to these patterns caused by thrusters located at various orientations. Hall thrusters exhibit several plasma instabilities, such as drift waves and transit time oscillations. This can introduce phase noise in the communication signals, which is highly undesirable, especially for digital signals. We are modeling these instabilities, which will be added to our simulations. Our codes make use of client/server software, allowing easy configuration setup and web access.
Fast Camera Imaging of Hall Thruster Ignition
C.L. Ellison, Y. Raitses and N.J. Fisch
2011-02-24
Hall thrusters provide efficient space propulsion by electrostatic acceleration of ions. Rotating electron clouds in the thruster overcome the space charge limitations of other methods. Images of the thruster startup, taken with a fast camera, reveal a bright ionization period which settles into steady state operation over 50 μs. The cathode introduces azimuthal asymmetry, which persists for about 30 μs into the ignition. Plasma thrusters are used on satellites for repositioning, orbit correction and drag compensation. The advantage of plasma thrusters over conventional chemical thrusters is that the exhaust energies are not limited by chemical energy to about an electron volt. For xenon Hall thrusters, the ion exhaust velocity can be 15-20 km/s, compared to 5 km/s for a typical chemical thruster
Multipole expansion in the quantum hall effect
NASA Astrophysics Data System (ADS)
Cappelli, Andrea; Randellini, Enrico
2016-03-01
The effective action for low-energy excitations of Laughlin's states is obtained by systematic expansion in inverse powers of the magnetic field. It is based on the W- infinity symmetry of quantum incompressible fluids and the associated higher-spin fields. Besides reproducing the Wen and Wen-Zee actions and the Hall viscosity, this approach further indicates that the low-energy excitations are extended objects with dipolar and multipolar moments.
The Hall D Physics Program at JLab
Leckey, John P.
2012-09-01
GlueX is one of the flagship experiments of the 12 GeV era at the Thomas Jefferson National Accelerator Facility (JLab). The energy of the electron accelerator at JLab is presently undergoing an upgrade from 6 GeV to 12 GeV and a 4th experimental hall (Hall D) is being added. The GlueX experimental apparatus consists of a tagged coherent bremsstrahlung photon beam incident on a liquid hydrogen target. The photoproduced mesons, which are created inside of a 2.2 T solenoid, will then pass through a pair of drift chambers and eventually deposit their energy into either of two calorimeters, depending on their respective angles. GlueX will attempt to map out the light meson spectrum and search for meson-gluon hybrids to better understand the confinement of quarks and gluons in quantum chromodynamics (QCD). There is little data on the photoproduction of light mesons and the GlueX experiment will exceed the current photoproduction data by several orders of magnitude in the first year alone. Photoproduction is specifically well suited to search for meson-gluon hybrids because in the flux tube model the production cross-sections are higher for meson-gluon hybrids from photons, with the spins of the virtual quark-antiquark pair aligned, than from other sources such as pions, with the spins of the quark-antiquark pair anti-aligned. There are also other Hall D experiments proposed to look for physics beyond the Standard Model by studying Eta rare or forbidden decay channels such as eta to two neutral pions. The 12 GeV upgrade of the JLab accelerator and the complete physics program of Hall D will be presented.
Hall Effect Measured Using a Waveguide Tee
NASA Astrophysics Data System (ADS)
Coppock, Joyce; Anderson, James; Johnson, William
2013-03-01
We describe a simple microwave apparatus to measure the Hall effect in semiconductor wafers. The advantage of this technique is that it does not require contacts on the sample, unlike the Van der Pauw method.[1] Our method consists of placing the semiconductor wafer into a slot cut in an X-band waveguide tee and placing the tee in the center of an electromagnet. The next step is to inject power into two arms of the tee and to balance the output so that no power comes out of the third arm of the tee at zero magnetic field. Application of a nonzero magnetic field gives a Hall signal that is linear in the magnetic field and which reverses phase when the magnetic field is reversed. We use a network analyzer to measure the ratio of the Hall signal to the input power. This method yields the semiconductor mobility in the wafer, which we can compare for calibration purposes with mobility data from our Van der Pauw measurements. This talk presents data for silicon and germanium samples doped with boron or phosphorus. Preliminary measurements on doped III-V semiconductor samples will also be presented.
A Magnetic Balance with Hall Effect Sensors
NASA Astrophysics Data System (ADS)
Sawada, Hideo; Kunimasu, Tetsuya; Suda, Shinichi; Mizoguti, Yasushi; Okada, Takumi
Magnetic force acting on a model fixed at the center of the JAXA 60cm MSBS was measured with an industry manufactured balance system when MSBS control coil currents were varied. At the same time, magnetic field intensity was also measured with 11 Hall sensors, which were arranged around the MSBS test section. From relations between coil currents and its corresponding controlled magnetic forces, regressive curves were given and maximum deviation from the curves was evaluated. From relations between Hall sensor outputs and the magnetic forces, regressive curves and deviation were also obtained. Obtained results show Hall sensor outputs are much better indexes of balance than the coil currents. The maximum deviations were reduced to a half or one-third times as much as those evaluated using the control coil currents. However, when couples acting on the model are controlled, they are not effective to reduce hysteresis phenomenon in the relation. The deviation can be reduced by decreasing the range of calibration. Then, the error of the balance of the MSBS was reduced to about 1% of the calibration range.
Integer quantum Hall effect and correlated disorder
Greshnov, A. A. Zegrya, G. G.
2007-11-15
The effect of the form of the random potential of impurities and defects on the longitudinal {sigma}{sub xx} and Hall {sigma}{sub xy} components of conductivity in the mode of the integer quantum Hall effect is theoretically investigated. It is shown that the width of the Hall conductivity plateau as well as the peak values of the longitudinal conductivity heavily depend on the ratio {lambda}/a{sub H} between the random potential correlation length and the magnetic length. For the first time, it is established that in the case of the short-wavelength potential {lambda} << a{sub H}, the peak values of {sigma}{sub xx}{sup (N)} are directly proportional to the Landau level number N {>=} 1, {sigma}{sub xx} = 0.5Ne{sup 2}/h, whereas the peak values of {sigma}{sub xx}{sup (N)} are independent of the Landau level number in the case of the long-wavelength potential {lambda} >> a{sub H}, and their magnitude is much lower than 0.5e{sup 2}/h. The obtained results are in good agreement with the available experimental data.
Generic superweak chaos induced by Hall effect.
Ben-Harush, Moti; Dana, Itzhack
2016-05-01
We introduce and study the "kicked Hall system" (KHS), i.e., charged particles periodically kicked in the presence of uniform magnetic (B) and electric (E) fields that are perpendicular to each other and to the kicking direction. We show that for resonant values of B and E and in the weak-chaos regime of sufficiently small nonintegrability parameter κ (the kicking strength), there exists a generic family of periodic kicking potentials for which the Hall effect from B and E significantly suppresses the weak chaos, replacing it by "superweak" chaos (SWC). This means that the system behaves as if the kicking strength were κ^{2} rather than κ. For E=0, SWC is known to be a classical fingerprint of quantum antiresonance, but it occurs under much less generic conditions, in particular only for very special kicking potentials. Manifestations of SWC are a decrease in the instability of periodic orbits and a narrowing of the chaotic layers, relative to the ordinary weak-chaos case. Also, for global SWC, taking place on an infinite "stochastic web" in phase space, the chaotic diffusion on the web is much slower than the weak-chaos one. Thus, the Hall effect can be relatively stabilizing for small κ. In some special cases, the effect is shown to cause ballistic motion for almost all parameter values. The generic global SWC on stochastic webs in the KHS appears to be the two-dimensional closest analog to the Arnol'd web in higher dimensional systems. PMID:27300880
Generic superweak chaos induced by Hall effect
NASA Astrophysics Data System (ADS)
Ben-Harush, Moti; Dana, Itzhack
2016-05-01
We introduce and study the "kicked Hall system" (KHS), i.e., charged particles periodically kicked in the presence of uniform magnetic (B ) and electric (E ) fields that are perpendicular to each other and to the kicking direction. We show that for resonant values of B and E and in the weak-chaos regime of sufficiently small nonintegrability parameter κ (the kicking strength), there exists a generic family of periodic kicking potentials for which the Hall effect from B and E significantly suppresses the weak chaos, replacing it by "superweak" chaos (SWC). This means that the system behaves as if the kicking strength were κ2 rather than κ . For E =0 , SWC is known to be a classical fingerprint of quantum antiresonance, but it occurs under much less generic conditions, in particular only for very special kicking potentials. Manifestations of SWC are a decrease in the instability of periodic orbits and a narrowing of the chaotic layers, relative to the ordinary weak-chaos case. Also, for global SWC, taking place on an infinite "stochastic web" in phase space, the chaotic diffusion on the web is much slower than the weak-chaos one. Thus, the Hall effect can be relatively stabilizing for small κ . In some special cases, the effect is shown to cause ballistic motion for almost all parameter values. The generic global SWC on stochastic webs in the KHS appears to be the two-dimensional closest analog to the Arnol'd web in higher dimensional systems.
Anode Fall Formation in a Hall Thruster
Leonid A. Dorf; Yevgeny F. Raitses; Artem N. Smirnov; Nathaniel J. Fisch
2004-06-29
As was reported in our previous work, accurate, nondisturbing near-anode measurements of the plasma density, electron temperature, and plasma potential performed with biased and emissive probes allowed the first experimental identification of both electron-repelling (negative anode fall) and electron-attracting (positive anode fall) anode sheaths in Hall thrusters. An interesting new phenomenon revealed by the probe measurements is that the anode fall changes from positive to negative upon removal of the dielectric coating, which appears on the anode surface during the course of Hall thruster operation. As reported in the present work, energy dispersion spectroscopy analysis of the chemical composition of the anode dielectric coating indicates that the coating layer consists essentially of an oxide of the anode material (stainless steel). However, it is still unclear how oxygen gets into the thruster channel. Most importantly, possible mechanisms of anode fall formation in a Hall thruster with a clean and a coated anodes are analyzed in this work; practical implication of understanding the general structure of the electron-attracting anode sheath in the case of a coated anode is also discussed.
NASA Astrophysics Data System (ADS)
Kim, Sang-Il; Kim, Dong-Jun; Seo, Min-Su; Park, Byong-Guk; Park, Seung-Young
2015-05-01
The dependence of the measured DC voltage on the non-magnetic material (NM) in NM/CoFeB and CoFeB/NM bilayers is studied under ferromagnetic resonance conditions in a TE011 resonant cavity. The directional change of the inverse spin Hall effect (ISHE) voltage VISHE for the stacking order of the bilayer can separate the pure VISHE and the anomalous Hall effect (AHE) voltage VAHE utilizing the method of addition and subtraction. The Ta and Ti NMs show a broad deviation of the spin Hall angle θISH, which originates from the AHE in accordance with the high resistivity of NMs. However, the Pt and Pd NMs show that the kinds of NMs with low resistivity are consistent with the previously reported θISH values. Therefore, the characteristics that NM should simultaneously satisfy to obtain a reasonable VISHE value in bilayer systems are large θISH and low resistivity.
Quantized anomalous Hall effect in two-dimensional ferromagnets: quantum Hall effect in metals.
Onoda, Masaru; Nagaosa, Naoto
2003-05-23
We study the effect of disorder on the anomalous Hall effect (AHE) in two-dimensional ferromagnets. The topological nature of the AHE leads to the integer quantum Hall effect from a metal, i.e., the quantization of sigma(xy) induced by the localization except for the few extended states carrying Chern numbers. Extensive numerical study on a model reveals that Pruisken's two-parameter scaling theory holds even when the system has no gap with the overlapping multibands and without the uniform magnetic field. Therefore, the condition for the quantized AHE is given only by the Hall conductivity sigma(xy) without the quantum correction, i.e., /sigma(xy)/>e(2)/(2h).
Geometric Aspects of Quantum Hall States
NASA Astrophysics Data System (ADS)
Gromov, Andrey
Explanation of the quantization of the Hall conductance at low temperatures in strong magnetic field is one of the greatest accomplishments of theoretical physics of the end of the 20th century. Since the publication of the Laughlin's charge pumping argument condensed matter theorists have come a long way to topological insulators, classification of noninteracting (and sometimes interacting) topological phases of matter, non-abelian statistics, Majorana zero modes in topological superconductors and topological quantum computation---the framework for "error-free'' quantum computation. While topology was very important in these developments, geometry has largely been neglected. We explore the role of space-time symmetries in topological phases of matter. Such symmetries are responsible for the conservation of energy, momentum and angular momentum. We will show that if these symmetries are maintained (at least on average) then in addition to Hall conductance there are other, in principle, measurable transport coefficients that are quantized and sensitive to topological phase transition. Among these coefficients are non-dissipative viscosity of quantum fluids, known as Hall viscosity; thermal Hall conductance, and a recently discovered coefficient---orbital spin variance. All of these coefficients can be computed as linear responses to variations of geometry of a physical sample. We will show how to compute these coefficients for a variety of abelian and non-abelian quantum Hall states using various analytical tools: from RPA-type perturbation theory to non-abelian Chern-Simons-Witten effective topological quantum field theory. We will explain how non-Riemannian geometry known as Newton-Cartan (NC) geometry arises in the computation of momentum and energy transport in non-relativistic gapped systems. We use this geometry to derive a number of thermodynamic relations and stress the non-relativistic nature of condensed matter systems. NC geometry is also useful in the
Low-Power Magnetically Shielded Hall Thrusters
NASA Astrophysics Data System (ADS)
Conversano, Ryan William
This dissertation presents an investigation of the applicability of magnetic shielding to low-power Hall thrusters as a means to significantly improve operational lifetime. The key life-limiting factors of conventional Hall thrusters, including ion-bombardment sputter erosion of the discharge channel and high-energy electron power deposition to the channel walls, have been investigated extensively for a wide range of thruster scales. As thruster power is reduced to the "miniature" (i.e. sub-500 W) power regime, the increased surface-to-volume ratio of the discharge channel and decreased thruster component sizes promotes increased plasma-wall interactions and susceptibility to overheating, thereby reducing thruster operational lifetime and performance. Although methods for compensating for these issues have been investigated, unshielded miniature Hall thrusters are generally limited to sub-45% anode efficiencies and maximum lifetimes on the order of 1,000 h. A magnetically shielded magnetic field topology aims to maintain a low electron temperature along the channel surfaces and a plasma potential near that of the discharge voltage along the entire surface of the discharge channel along its axial length. These features result in a reduction of the kinetic energy of ions that impact the channel surfaces to near to or below the sputtering threshold, thus preventing significant ion-bombardment erosion of the discharge channel. Improved confinement of high-energy electrons is another byproduct of the field structure, aiding in the reduction of electron power deposition to the channel. Magnetic shielding has been shown to dramatically reduce plasma-wall interactions on 4--6 kW Hall thrusters, resulting in significant increases in projected operational lifetimes with minimal effects to thruster performance. In an effort to explore the scalability of magnetic shielding to low-power devices, two magnetically shielded miniature Hall thrusters were designed, fabricated and
Anomalous spin Hall effects in Dresselhaus (110) quantum wells
NASA Astrophysics Data System (ADS)
Liu, Ming-Hao; Chang, Ching-Ray
2010-10-01
Anomalous spin Hall effects that belong to the intrinsic type in Dresselhaus (110) quantum wells are discussed. For the out-of-plane spin component, antisymmetric current-induced spin polarization induces opposite spin Hall accumulation, even though there is no spin-orbit force due to Dresselhaus (110) coupling. A surprising feature of this spin Hall induction is that the spin accumulation sign does not change upon bias reversal. Contribution to the spin Hall accumulation from the spin Hall induction and the spin deviation due to intrinsic spin-orbit force as well as extrinsic spin scattering can be straightforwardly distinguished simply by reversing the bias. For the in-plane component, inclusion of a weak Rashba coupling leads to a new type of Sy intrinsic spin Hall effect solely due to spin-orbit-force-driven spin separation.
Role of electrical field in quantum Hall effect of graphene
NASA Astrophysics Data System (ADS)
Luo, Ji
2013-01-01
The ballistic motion of carriers of graphene in an orthogonal electromagnetic field is investigated to explain quantum Hall effect of graphene under experimental conditions. With the electrical field, all electronic eigen-states have the same expectation value of the velocity operator, or classically, all carriers move in cycloid-like curves with the same average velocity. This velocity is the origin of the Hall conductance and its magnitude is just appropriate so that the quantized Hall conductance is exactly independent of the external field. Electrical field changes each Landau level into a bundle of energies. Hall conductance plateaus occur in small fields as bundle gaps exist and are destroyed in intermediate fields as bundles overlap. As the electrical field tends to the critical point, all bundles have the same width, and bundle gaps increase to infinity rapidly. As a result, saturation of the Hall conductance may be observed. Electrical field thus demonstrates nonlinear effects on the Hall conductance.
Giant Room Temperature Interface Spin Hall and Inverse Spin Hall Effects
NASA Astrophysics Data System (ADS)
Wang, Lei; Wesselink, R. J. H.; Liu, Yi; Yuan, Zhe; Xia, Ke; Kelly, Paul J.
2016-05-01
The spin Hall angle (SHA) is a measure of the efficiency with which a transverse spin current is generated from a charge current by the spin-orbit coupling and disorder in the spin Hall effect (SHE). In a study of the SHE for a Pt |Py (Py =Ni80Fe20 ) bilayer using a first-principles scattering approach, we find a SHA that increases monotonically with temperature and is proportional to the resistivity for bulk Pt. By decomposing the room temperature SHE and inverse SHE currents into bulk and interface terms, we discover a giant interface SHA that dominates the total inverse SHE current with potentially major consequences for applications.
Size dependence of microscopic Hall sensor detection limits.
Vervaeke, K; Simoen, E; Borghs, G; Moshchalkov, V V
2009-07-01
In this paper the magnetic field detection limits of microscopic Hall sensors are investigated as a function of their lateral size. Hall sensors fabricated from GaAs/AlGaAs heterostructures and silicon are experimentally investigated at different temperatures using Hall effect and noise spectrum measurements. At room temperature a clear size dependence of the detection limit is observed, whereas at low temperatures this dependence is found to disappear. The results are explained using the theory of noise in semiconductors.
Fabrication of a vector Hall sensor for magnetic microscopy
NASA Astrophysics Data System (ADS)
Gregušová, D.; Cambel, V.; Fedor, J.; Kúdela, R.; Šoltýs, J.; Lalinský, T.; Kostič, I.; Bending, S. J.
2003-05-01
We have developed a micromachined Hall sensor for scanning the entire magnetic field vector whose active dimensions are an order of magnitude smaller (˜5 μm) than the smallest existing vector field sensor. It is realized by patterning three Hall probes on the tilted faces of epitaxy-overgrown GaAs-based pyramidal-shaped mesa structures. Data from these "tilted" Hall probes are used to reconstruct the full magnetic field vector.
Faster Hall-Effect Current-Measuring Circuit
NASA Technical Reports Server (NTRS)
Sullender, Craig C.; Johnson, Daniel D.; Walker, Daniel D.
1993-01-01
Current-measuring circuit operates on Hall-effect-sensing and magnetic-field-nulling principles similar to those described in article, "Nulling Hall-Effect Current-Measuring Circuit" (LEW-15023), but simpler and responds faster. Designed without feedback loop, and analog pulse-width-modulated output indicates measured current. Circuit measures current at frequency higher than bandwidth of its Hall-effect sensor.
Basic Instrumentation for Hall A at Jefferson Jab
The Jefferson Lab Hall A Collaboration
2003-07-01
The instrumentation in Hall A at the JLab was designed to study electro- and photo-induced reactions at very high luminosity and good momentum and angular resolution for at least one of the reaction products. A collaboration of approximately 50 institutions from all over the world has actively contributed and participated in the design, construction and commissioning of the Hall A instrumentation. The basic Hall A equipment is described herein.
Factors Affecting the Efficiency of Krypton Hall Thrusters
NASA Technical Reports Server (NTRS)
Hofer, Richard R.; Peterson, Peter Y.; Jacobson, David T.; Manzella, David M.
2004-01-01
The krypton-fueled Hall thruster offers the possibility of high-specific impulse and long lifetime. NASA's series of Hall thrusters have demonstrated krypton efficiencies only 5 - 15% less than xenon. Larger thrusters have smaller differences in efficiency. Plasma measurements have demonstrated that efficiency is reduced due to a decrease in mass utilization. Current efforts are considering the implications of these results, and how design changes can be made to increase the efficiency of krypton Hall thrusters.
Supersymmetric Quantum-Hall Effect on a Fuzzy Supersphere
Hasebe, Kazuki
2005-05-27
Supersymmetric quantum-Hall liquids are constructed on a supersphere in a supermonopole background. We derive a supersymmetric generalization of the Laughlin wave function, which is a ground state of a hard-core OSp(1 vertical bar 2) invariant Hamiltonian. We also present excited topological objects, which are fractionally charged deficits made by super Hall currents. Several relations between quantum-Hall systems and their supersymmetric extensions are discussed.
Charge carrier coherence and Hall effect in organic semiconductors
Yi, H. T.; Gartstein, Y. N.; Podzorov, V.
2016-03-30
Hall effect measurements are important for elucidating the fundamental charge transport mechanisms and intrinsic mobility in organic semiconductors. However, Hall effect studies frequently reveal an unconventional behavior that cannot be readily explained with the simple band-semiconductor Hall effect model. Here, we develop an analytical model of Hall effect in organic field-effect transistors in a regime of coexisting band and hopping carriers. The model, which is supported by the experiments, is based on a partial Hall voltage compensation effect, occurring because hopping carriers respond to the transverse Hall electric field and drift in the direction opposite to the Lorentz force actingmore » on band carriers. We show that this can lead in particular to an underdeveloped Hall effect observed in organic semiconductors with substantial off-diagonal thermal disorder. Lastly, our model captures the main features of Hall effect in a variety of organic semiconductors and provides an analytical description of Hall mobility, carrier density and carrier coherence factor.« less
Probing magnetic microstructures with quasi-ballistic Hall crosses
NASA Astrophysics Data System (ADS)
Fasbender, S.; Schluck, J.; Cerchez, M.; Heinzel, T.; Sievers, S.; Pierz, K.; Schumacher, H. W.
2016-03-01
Hall sensing is performed on a localized magnetic field pattern using a quasi-ballistic Hall cross device. The Hall resistance shows a pronounced peak as a function of the magnetic field amplitude which is absent in the magnetization hysteresis loop. This non-monotonic response exemplifies qualitatively the failure of conventional Hall sensing. It is demonstrated how, by using a numerical simulation based on the Landauer-Büttiker model, the amplitude of the magnetic field profile can be determined from such measurements.
Dynamic Feedback in Ferromagnet-Spin Hall Metal Heterostructures
NASA Astrophysics Data System (ADS)
Cheng, Ran; Zhu, Jian-Gang; Xiao, Di
2016-08-01
In ferromagnet-normal-metal heterostructures, spin pumping and spin-transfer torques are two reciprocal processes that occur concomitantly. Their interplay introduces a dynamic feedback effect interconnecting energy dissipation channels of both magnetization and current. By solving the spin diffusion process in the presence of the spin Hall effect in the normal metal, we show that the dynamic feedback gives rise to (i) a nonlinear magnetic damping that is crucial to sustain uniform steady-state oscillations of a spin Hall oscillator at large angles and (ii) a frequency-dependent spin Hall magnetoimpedance that reduces to the spin Hall magnetoresistance in the dc limit.
Linear magnetization dependence of the intrinsic anomalous Hall effect.
Zeng, Changgan; Yao, Yugui; Niu, Qian; Weitering, Hanno H
2006-01-27
The anomalous Hall effect is investigated experimentally and theoretically for ferromagnetic thin films of Mn5Ge3. We have separated the intrinsic and extrinsic contributions to the experimental anomalous Hall effect and calculated the intrinsic anomalous Hall conductivity from the Berry curvature of the Bloch states using first-principles methods. The intrinsic anomalous Hall conductivity depends linearly on the magnetization, which can be understood from the long-wavelength fluctuations of the spin orientation at finite temperatures. The quantitative agreement between theory and experiment is remarkably good, not only near 0 K but also at finite temperatures, up to about approximately 240 K (0.8TC).
Dynamic Feedback in Ferromagnet-Spin Hall Metal Heterostructures.
Cheng, Ran; Zhu, Jian-Gang; Xiao, Di
2016-08-26
In ferromagnet-normal-metal heterostructures, spin pumping and spin-transfer torques are two reciprocal processes that occur concomitantly. Their interplay introduces a dynamic feedback effect interconnecting energy dissipation channels of both magnetization and current. By solving the spin diffusion process in the presence of the spin Hall effect in the normal metal, we show that the dynamic feedback gives rise to (i) a nonlinear magnetic damping that is crucial to sustain uniform steady-state oscillations of a spin Hall oscillator at large angles and (ii) a frequency-dependent spin Hall magnetoimpedance that reduces to the spin Hall magnetoresistance in the dc limit. PMID:27610880
Diagnostics Systems for Permanent Hall Thrusters Development
NASA Astrophysics Data System (ADS)
Ferreira, Jose Leonardo; Soares Ferreira, Ivan; Santos, Jean; Miranda, Rodrigo; Possa, M. Gabriela
This work describes the development of Permanent Magnet Hall Effect Plasma Thruster (PHALL) and its diagnostic systems at The Plasma Physics Laboratory of University of Brasilia. The project consists on the construction and characterization of plasma propulsion engines based on the Hall Effect. Electric thrusters have been employed in over 220 successful space missions. Two types stand out: the Hall-Effect Thruster (HET) and the Gridded Ion Engine (GIE). The first, which we deal with in this project, has the advantage of greater simplicity of operation, a smaller weight for the propulsion subsystem and a longer shelf life. It can operate in two configurations: magnetic layer and anode layer, the difference between the two lying in the positioning of the anode inside the plasma channel. A Hall-Effect Thruster-HET is a type of plasma thruster in which the propellant gas is ionized and accelerated by a magneto hydrodynamic effect combined with electrostatic ion acceleration. So the essential operating principle of the HET is that it uses a J x B force and an electrostatic potential to accelerate ions up to high speeds. In a HET, the attractive negative charge is provided by electrons at the open end of the Thruster instead of a grid, as in the case of the electrostatic ion thrusters. A strong radial magnetic field is used to hold the electrons in place, with the combination of the magnetic field and the electrostatic potential force generating a fast circulating electron current, the Hall current, around the axis of the Thruster, mainly composed by drifting electrons in an ion plasma background. Only a slow axial drift towards the anode occurs. The main attractive features of the Hall-Effect Thruster are its simple design and operating principles. Most of the Hall-Effect Thrusters use electromagnet coils to produce the main magnetic field responsible for plasma generation and acceleration. In this paper we present a different new concept, a Permanent Magnet Hall
Waage, J K; Mumford, J D
2008-02-27
The prevention and control of new pest and disease introductions is an agricultural challenge which is attracting growing public interest. This interest is in part driven by an impression that the threat is increasing, but there has been little analysis of the changing rates of biosecurity threat, and existing evidence is equivocal. Traditional biosecurity systems for animals and plants differ substantially but are beginning to converge. Bio-economic modelling of risk will be a valuable tool in guiding the allocation of limited resources for biosecurity. The future of prevention and management systems will be strongly influenced by new technology and the growing role of the private sector. Overall, today's biosecurity systems are challenged by changing national priorities regarding trade, by new concerns about environmental effects of biological invasions and by the question 'who pays?'. Tomorrow's systems may need to be quite different to be effective. We suggest three changes: an integration of plant and animal biosecurity around a common, proactive, risk-based approach; a greater focus on international cooperation to deal with threats at source; and a commitment to refocus biosecurity on building resilience to invasion into agroecosystems rather than building walls around them.
Elyasi, Mehrdad; Bhatia, Charanjit S.; Yang, Hyunsoo
2015-02-14
We have proposed a method to synchronize multiple spin-transfer torque oscillators based on spin pumping, inverse spin Hall, and spin Hall effects. The proposed oscillator system consists of a series of nano-magnets in junction with a normal metal with high spin-orbit coupling, and an accumulative feedback loop. We conduct simulations to demonstrate the effect of modulated charge currents in the normal metal due to spin pumping from each nano-magnet. We show that the interplay between the spin Hall effect and inverse spin Hall effect results in synchronization of the nano-magnets.
Nonequilibrium spin polarization induced charge Hall effect
NASA Astrophysics Data System (ADS)
Hou, Dazhi; Qiu, Z.; Iguchi, R.; Sato, K.; Uchida, K.; Bauer, G. W.; Saitoh, Eiji
2015-03-01
The nonequilibrium spin polarization lies at the heart of information processing in spin-based devices. The generation and manipulation of the spin polarization have been realized by various approaches, however, the spin polarization is usually considered to have negligible effect on the electric transport property, especially for systems of high electron concentration like metals (ɛF ~ eV). Here we show that the nonequilibrium spin polarization can cause a novel Hall voltage in a conventional metallic alloy at room temperature, which is due to a new mechanism and closely related to the spin Nernst effect.
Excitons in the Fractional Quantum Hall Effect
DOE R&D Accomplishments Database
Laughlin, R. B.
1984-09-01
Quasiparticles of charge 1/m in the Fractional Quantum Hall Effect form excitons, which are collective excitations physically similar to the transverse magnetoplasma oscillations of a Wigner crystal. A variational exciton wavefunction which shows explicitly that the magnetic length is effectively longer for quasiparticles than for electrons is proposed. This wavefunction is used to estimate the dispersion relation of these excitons and the matrix elements to generate them optically out of the ground state. These quantities are then used to describe a type of nonlinear conductivity which may occur in these systems when they are relatively clean.
Chiral partition functions of quantum Hall droplets
Cappelli, Andrea Viola, Giovanni; Zemba, Guillermo R.
2010-02-15
Chiral partition functions of conformal field theory describe the edge excitations of isolated Hall droplets. They are characterized by an index specifying the quasiparticle sector and transform among themselves by a finite-dimensional representation of the modular group. The partition functions are derived and used to describe electron transitions leading to Coulomb blockade conductance peaks. We find the peak patterns for Abelian hierarchical states and non-Abelian Read-Rezayi states, and compare them. Experimental observation of these features can check the qualitative properties of the conformal field theory description, such as the decomposition of the Hilbert space into sectors, involving charged and neutral parts, and the fusion rules.
Segmented electrode hall thruster with reduced plume
Fisch, Nathaniel J.; Raitses, Yevgeny
2004-08-17
An apparatus and method for thrusting plasma, utilizing a Hall thruster with segmented electrodes along the channel, which make the acceleration region as localized as possible. Also disclosed are methods of arranging the electrodes so as to minimize erosion and arcing. Also disclosed are methods of arranging the electrodes so as to produce a substantial reduction in plume divergence. The use of electrodes made of emissive material will reduce the radial potential drop within the channel, further decreasing the plume divergence. Also disclosed is a method of arranging and powering these electrodes so as to provide variable mode operation.
Matrix Product States and Fractional Quantum Hall
NASA Astrophysics Data System (ADS)
Bernevig, B. Andrei; Estienne, Benoit; Regnault, Nicolas; Papic, Zlatko
2013-03-01
We present an exact matrix product state expansion (MPS) for a large series of Jack polynomial wavefunctions which serve as Fractional Quantum Hall ground-states of pseudopotential Hamiltonians. Using the basis of descendants in Virasoro and W algebras we build MPS descriptions of the (k,2) Jacks which include the Moore-Read state and the Gaffnian state, as well as MPS representation of the Z3 Read-Rezayi state. We then give a general method for computing MPS representations for other non-abelian states and their quasiholes.
Supercurrent in the quantum Hall regime
NASA Astrophysics Data System (ADS)
Amet, F.; Ke, C. T.; Borzenets, I. V.; Wang, J.; Watanabe, K.; Taniguchi, T.; Deacon, R. S.; Yamamoto, M.; Bomze, Y.; Tarucha, S.; Finkelstein, G.
2016-05-01
A promising route for creating topological states and excitations is to combine superconductivity and the quantum Hall (QH) effect. Despite this potential, signatures of superconductivity in the QH regime remain scarce, and a superconducting current through a QH weak link has been challenging to observe. We demonstrate the existence of a distinct supercurrent mechanism in encapsulated graphene samples contacted by superconducting electrodes, in magnetic fields as high as 2 tesla. The observation of a supercurrent in the QH regime marks an important step in the quest for exotic topological excitations, such as Majorana fermions and parafermions, which may find applications in fault-tolerant quantum computing.
Supercurrent in the quantum Hall regime.
Amet, F; Ke, C T; Borzenets, I V; Wang, J; Watanabe, K; Taniguchi, T; Deacon, R S; Yamamoto, M; Bomze, Y; Tarucha, S; Finkelstein, G
2016-05-20
A promising route for creating topological states and excitations is to combine superconductivity and the quantum Hall (QH) effect. Despite this potential, signatures of superconductivity in the QH regime remain scarce, and a superconducting current through a QH weak link has been challenging to observe. We demonstrate the existence of a distinct supercurrent mechanism in encapsulated graphene samples contacted by superconducting electrodes, in magnetic fields as high as 2 tesla. The observation of a supercurrent in the QH regime marks an important step in the quest for exotic topological excitations, such as Majorana fermions and parafermions, which may find applications in fault-tolerant quantum computing. PMID:27199424
Disordered Interactions and Fractional Quantum Hall States
NASA Astrophysics Data System (ADS)
Degottardi, Wade; Hafezi, Mohammad
The possibility that topological ordered states may be realized in photonic systems has recently attracted a great deal of attention. Given the rich phenomenology of the fractional quantum Hall effect, the bosonic Laughlin states have been of particular focus in this context. These states are known to arise in strongly nonlinear photonic lattices with artificial gauge fields, where nonlinearities associated with the resonators mimic on-site interactions. These effective interaction strengths are not universal and are subject to spatial disorder. We present a detailed study of the stability of these states and what implications they have for experiments.
Anomalous Hall effect in disordered multiband metals.
Kovalev, Alexey A; Sinova, Jairo; Tserkovnyak, Yaroslav
2010-07-16
We present a microscopic theory of the anomalous Hall effect (AHE) in metallic multiband ferromagnets, which accounts for all scattering-independent contributions, i.e., both the intrinsic and the so-called side jump. For a model of Gaussian disorder, the AHE is expressed solely in terms of the material's electronic band structure. Our theory handles systematically the interband-scattering coherence effects. We demonstrate the method in the 2D Rashba and 3D ferromagnetic (III,Mn)V semiconductor models. Our formalism is directly amenable to ab initio treatments for a wide range of ferromagnetic metals.
Anomalous Hall effect in Weyl metals.
Burkov, A A
2014-10-31
We present a theory of the anomalous Hall effect (AHE) in a doped Weyl semimetal, or Weyl metal, including both intrinsic and extrinsic (impurity scattering) contributions. We demonstrate that a Weyl metal is distinguished from an ordinary ferromagnetic metal by the absence of the extrinsic and the Fermi surface part of the intrinsic contributions to the AHE, as long as the Fermi energy is sufficiently close to the Weyl nodes. The AHE in a Weyl metal is thus shown to be a purely intrinsic, universal property, fully determined by the location of the Weyl nodes in the first Brillouin zone.
Future Hypernuclear Program at JLAB Hall C
Satoshi Nakamura
2005-05-01
Encouraged by the success of the first hypernuclear spectroscopy through the (e,e'K+) reaction (JLab E89-009), a new improved experiment with a newly developed High resolution Kaon Spectrometer (HKS) and a new configuration of the electron spectrometer is planned at the JLab Hall C. The introduction of the HKS will improve by a factor of two, the energy resolution which was limited by the previous kaon spectrometer. The hypernuclear yield and the signal to noise ratio will be also improved by a factor of 50 and 10, respectively.
Anomalous Hall Effect in a Kagome Ferromagnet
NASA Astrophysics Data System (ADS)
Ye, Linda; Wicker, Christina; Suzuki, Takehito; Checkelsky, Joseph; Joseph Checkelsky Team
The ferromagnetic kagome lattice is theoretically known to possess topological band structures. We have synthesized large single crystals of a kagome ferromagnet Fe3Sn2 which orders ferromagnetically well above room temperature. We have studied the electrical and magnetic properties of these crystals over a broad temperature and magnetic field range. Both the scaling relation of anomalous Hall effect and anisotropic magnetic susceptibility show that the ferromagnetism of Fe3Sn2 is unconventional. We discuss these results in the context of magnetism in kagome systems and relevance to the predicted topological properties in this class of compounds. This research is supported by DMR-1231319.
Anomalous hydrodynamics of fractional quantum Hall states
Wiegmann, P.
2013-09-15
We propose a comprehensive framework for quantum hydrodynamics of the fractional quantum Hall (FQH) states. We suggest that the electronic fluid in the FQH regime can be phenomenologically described by the quantized hydrodynamics of vortices in an incompressible rotating liquid. We demonstrate that such hydrodynamics captures all major features of FQH states, including the subtle effect of the Lorentz shear stress. We present a consistent quantization of the hydrodynamics of an incompressible fluid, providing a powerful framework to study the FQH effect and superfluids. We obtain the quantum hydrodynamics of the vortex flow by quantizing the Kirchhoff equations for vortex dynamics.
Programs in Animal Agriculture.
ERIC Educational Resources Information Center
Herring, Don R.; And Others
1980-01-01
Five topics relating to programs in animal agriculture are addressed: (1) the future of animal agriculture; (2) preparing teachers in animal agriculture; (3) how animal programs help young people; (4) a nontraditional animal agriculture program; and (5) developing competencies in animal agriculture. (LRA)
Cultural Composition: Stuart Hall on Ethnicity and the Discursive Turn.
ERIC Educational Resources Information Center
Drew, Julie
1998-01-01
Interviews Stuart Hall, a black public intellectual and an activist of the New Left. Discusses the growing disillusionment with cultural studies now that it is no longer in its ascendancy; the proliferation of pedagogical practices given a cultural studies tag; Hall's approval of the use of popular culture in the composition classroom; and the…
Cultural Group Perceptions of Racial Climates in Residence Halls.
ERIC Educational Resources Information Center
Johnson, Vanessa D.
2003-01-01
Study suggests that residence hall students at a predominantly White university perceive the racial climate of residence halls differently depending on their cultural group. Statistical significances occurred between Whites and one or more of the cultural minority groups. There were no significant differences between any of the ethnic minority…
The first vineyard concert hall in North America
NASA Astrophysics Data System (ADS)
Jaffe, Christopher; Rivera, Carlos
2002-11-01
The first vineyard or surround concert hall designed and built in the Western Hemisphere is the Sala Nezahualcoyotl in Mexico City. The Hall was completed in 1976 and is part of the Cultural Center at the Universidad Nacional Autonoma de Mexico. The hall was named after a Toltec poet, architect, and musician who lived in the 15th century and was the Renaissance man of his day. In order to provide the familiar traditional sound of the rectangular (shoebox) European Hall, the acoustic designers set the criteria for reverberation times through the frequency spectrum and the Initial Time Delay Gap at every seat in the house to match the measurements taken at the Grosser Musik vereinssaal in Vienna and Boston Symphony Hall. In this paper we discuss the techniques used to create the traditional sound in a vineyard hall and the reaction of musicians and audiences to the completed facility. The Sala was the model for Suntory Hall in Japan which in turn spawned a number of vineyard halls in Japan. Most recently, the vineyard style seems to be appealing to more and more symphonic organizations in Europe and North America.
Implementing Proactive Network Management Solutions in the Residence Halls
ERIC Educational Resources Information Center
Bedi, Param
2005-01-01
This paper discusses how to implement networking solutions in residence halls at Arcadia University in Philadelphia. Sections of the paper include: (1) About Arcadia University; (2) Residence Halls Network; (3) How Campus Manager Helped Arcadia University; (4) What Is Campus Manager; (5) How Campus Manager Works; (6) Campus Manager Remediation…
Varsity Hall: The Infirmary at the University of Virginia
ERIC Educational Resources Information Center
Christmas, William A.; Turner, James C.
2008-01-01
In the past 5 years, an important treasure for the field of college health was rediscovered and has been completely renovated. It is the original student infirmary, now called Varsity Hall, at the University of Virginia in Charlottesville. Varsity Hall is a significant rediscovery for those who are interested in the history of college health. This…
The Contributions of Joseph Sargent Hall to Appalachian Studies.
ERIC Educational Resources Information Center
Montgomery, Michael
The work of Joseph Sargent Hall, a pioneer researcher in Appalachian studies, is chronicled. Hall was hired by the National Park Service in 1937, as a graduate student, to document the lives and lore of older mountain residents allowed to remain in the Great Smoky Mountains after the land was purchased for a national park. His early efforts…
Useful Pedagogical Applications of the Classical Hall Effect
ERIC Educational Resources Information Center
Houari, Ahmed
2007-01-01
One of the most known phenomena in physics is the Hall effect. This is mainly due to its simplicity and to the wide range of its theoretical and practical applications. To complete the pedagogical utility of the Hall effect in physics teaching, I will apply it here to determine the Faraday constant as a fundamental physical number and the number…
Energy spectrum, dissipation, and spatial structures in reduced Hall magnetohydrodynamic
Martin, L. N.; Dmitruk, P.; Gomez, D. O.
2012-05-15
We analyze the effect of the Hall term in the magnetohydrodynamic turbulence under a strong externally supported magnetic field, seeing how this changes the energy cascade, the characteristic scales of the flow, and the dynamics of global magnitudes, with particular interest in the dissipation. Numerical simulations of freely evolving three-dimensional reduced magnetohydrodynamics are performed, for different values of the Hall parameter (the ratio of the ion skin depth to the macroscopic scale of the turbulence) controlling the impact of the Hall term. The Hall effect modifies the transfer of energy across scales, slowing down the transfer of energy from the large scales up to the Hall scale (ion skin depth) and carrying faster the energy from the Hall scale to smaller scales. The final outcome is an effective shift of the dissipation scale to larger scales but also a development of smaller scales. Current sheets (fundamental structures for energy dissipation) are affected in two ways by increasing the Hall effect, with a widening but at the same time generating an internal structure within them. In the case where the Hall term is sufficiently intense, the current sheet is fully delocalized. The effect appears to reduce impulsive effects in the flow, making it less intermittent.
Mary E. Hall: Dawn of the Professional School Librarian
ERIC Educational Resources Information Center
Alto, Teresa
2012-01-01
A century ago, a woman named Mary E. Hall convinced school leaders of the need for the professional school librarian--a librarian who cultivated a love of reading, academic achievement, and independent learning skills. After graduating from New York City's Pratt Institute Library School in 1895, Hall developed her vision for the high school…
30. VIEW OF DRILL HALL FROM SECOND FLOOR EAST BALCONY ...
30. VIEW OF DRILL HALL FROM SECOND FLOOR EAST BALCONY FACING WEST. SHOWS ALTERNATE BAY X BRACING OF ROOF TRUSSES. ALSO SHOWS TRUSSES, WINDOWS IN THE MONITOR, STAIRWAY AT THE SOUTHWEST CORNER OF THE DRILL HALL AND THE THREE LEVELS OF BENCHES ON THE BALCONY. - Yakima National Guard Armory, 202 South Third Street, Yakima, Yakima County, WA
25. VIEW FROM MAIN HALL THROUGH INTERIOR WINDOW TO SOLARIUM ...
25. VIEW FROM MAIN HALL THROUGH INTERIOR WINDOW TO SOLARIUM Note how much light enters this interior space from the solarium. The hall also receives light from the lightwell window of the main stairs to the third floor, out of sight to the left. - Woodrow Wilson House, 2340 South S Street, Northwest, Washington, District of Columbia, DC
A Model for Developing New Residence Hall Environments
ERIC Educational Resources Information Center
Hubbell, Robert N.; Sherwood, Grant P.
1973-01-01
This paper has the function of developing a residence hall interaction model utilizing three components: environmental options, student development needs, and human interaction categories. The paper discussed ways in which residence hall staff members could effect optimal learning opportunities by matching various environmental options to…
Hall-Effect Thruster Utilizing Bismuth as Propellant
NASA Technical Reports Server (NTRS)
Szabo, James; Gasdaska, Charles; Hruby, Vlad; Robin, Mike
2008-01-01
A laboratory-model Hall-effect spacecraft thruster was developed that utilizes bismuth as the propellant. Xenon was used in most prior Hall-effect thrusters. Bismuth is an attractive alternative because it has a larger atomic mass, a larger electron-impact-ionization cross-section, and is cheaper and more plentiful.
Whose Big Prize? A Response to Hall and Gunter
ERIC Educational Resources Information Center
Furlong, John
2009-01-01
This article presents the author's response to Hall and Gunter who accuse the author of trying to mount "a stout defence" of New Labour's reforms of the teaching profession. Hall and Gunter go further and accuse the author of "triumphalism" in his use of the title "Tony Blair's big prize". Their second and more serious challenge concerns the…
Contextual view of the Hall of Transportation from Yerba Buena ...
Contextual view of the Hall of Transportation from Yerba Buena Island, showing Palace of Fine and Decorative Arts (Building 3) at far right, camera facing northwest - Golden Gate International Exposition, Hall of Transportation, 440 California Avenue, Treasure Island, San Francisco, San Francisco County, CA
Student Satisfaction With Residence Hall Life at Miami. Survey Report.
ERIC Educational Resources Information Center
Keller, Michael J.
A random sample of students living in university housing at Miami University were surveyed about their satisfaction or dissatisfaction with three broad features of hall life: hall relationships, policies and programs; facilities and services; and staff. A list of 42 factors that were thought to relate to overall satisfaction with housing were…
High Life: 17th Annual Residence Hall Construction Report
ERIC Educational Resources Information Center
Agron, Joe
2006-01-01
Residence hall construction continues to be a priority for colleges and universities. With enrollments on the upswing, higher-education institutions are spending more and building larger facilities to entice students to live on campus. This article presents the findings of "American School & University's" 17th annual Residence Hall Construction…
35. Photographic copy of second floor plan of Bowditch Hall, ...
35. Photographic copy of second floor plan of Bowditch Hall, Alfred Hopkins & Associates, 1943. Drawing on file at Caretaker Site Office, Naval Undersea Warfare Center, New London. Copyright-free. - Naval Undersea Warfare Center, Bowditch Hall, 600 feet east of Smith Street & 350 feet south of Columbia Cove, West bank of Thames River, New London, New London County, CT
36. Photographic copy of third floor plan of Bowditch Hall, ...
36. Photographic copy of third floor plan of Bowditch Hall, Alfred Hopkins & Associates, 1943. Drawing on file at Caretaker Site Office, Naval Undersea Warfare Center, New London. Copyright-free. - Naval Undersea Warfare Center, Bowditch Hall, 600 feet east of Smith Street & 350 feet south of Columbia Cove, West bank of Thames River, New London, New London County, CT
34. Photographic copy of first floor plan of Bowditch Hall, ...
34. Photographic copy of first floor plan of Bowditch Hall, Alfred Hopkins & Associates, 1943. Drawing on file at Caretaker Site Office, Naval Undersea Warfare Center, New London. Copyright-free. - Naval Undersea Warfare Center, Bowditch Hall, 600 feet east of Smith Street & 350 feet south of Columbia Cove, West bank of Thames River, New London, New London County, CT
Pair spectrometer hodoscope for Hall D at Jefferson Lab
Barbosa, Fernando J.; Hutton, Charles L.; Sitnikov, Alexandre; Somov, Alexander S.; Somov, S.; Tolstukhin, Ivan
2015-09-21
We present the design of the pair spectrometer hodoscope fabricated at Jefferson Lab and installed in the experimental Hall D. The hodoscope consists of thin scintillator tiles; the light from each tile is collected using wave-length shifting fibers and detected using a Hamamatsu silicon photomultiplier. Light collection was measured using relativistic electrons produced in the tagger area of the experimental Hall B.
Stuart Hall on Racism and the Importance of Diasporic Thinking
ERIC Educational Resources Information Center
Rizvi, Fazal
2015-01-01
In this article, I want to show how my initial encounter with the work of Stuart Hall was grounded in my reading of the later philosophy of Ludwig Wittgenstein, and was shaped by my interest in understanding the nature of racism across the three countries in which I had lived. Over the years, Hall's various writings have helped me to make sense of…
A Larger Scale. Tenth Annual Residence Hall Construction Report.
ERIC Educational Resources Information Center
Argon, Joe
1999-01-01
Presents data from the American School & University's 10th Annual Residence Hall Construction Report that show dormitories are costing more per square foot to build while also becoming larger accommodations. Data tables are provided as are highlighted discussions that include residence hall design flexibility, environmental concerns and building…
Study Hall Policy and Practice among Illinois Public High Schools.
ERIC Educational Resources Information Center
Illinois State Board of Education, Springfield.
In response to questions raised by the Pupil Accounting System Advisory Group concerning the criteria for determining a day of attendance and whether study hall time should be counted when measuring attendance, the Illinois State Board of Education conducted a comprehensive survey to ascertain current study hall policy and practice among the…
Acoustic Requirements for a Multi-Purpose Hall.
ERIC Educational Resources Information Center
Schulte, W. Allen
2002-01-01
This case study examines the proposed design of a new lecture/recital hall in Centennial Hall at Lynchburg College that will be used for lectures, public events, a film studies course, and musical recitals. It explores the audio-visual challenges presented by the differing acoustical requirements for the building. (EV)
Brainstorming Interactive Exhibits for the Baseball Hall of Fame.
ERIC Educational Resources Information Center
Shapiro, David W.; Seidman, Steven
1996-01-01
Discusses incorporating interactive multimedia into the Baseball Hall of Fame in Cooperstown, New York. Presents examples of interactive exhibits from other museums and suggests ideas for the Hall of Fame to pursue: simulations of batting, signal use, and umpiring; a quiz show; a visitor poll; CD-ROM software; and an interactive database.…
Repurposing the Caltech Robinson Hall Coelostat
NASA Astrophysics Data System (ADS)
Treffers, Richard R.; Loisos, G.; Ubbelohde, M.; Douglas, S.; Martinez, M.
2013-01-01
We describe the repurposing of the historic coelostat atop Caltech’s Robinson Hall for building lighting, public education and scientific research. The coelostat was originally part of George Ellery Hale’s vision of the Astrophysical Laboratory on the Caltech campus in 1932. The coelostat, designed by Russell Porter, has a 36 inch diameter primary mirror a 30 inch diameter secondary mirror and provides a 24 inch un-vignetted beam of sunlight into the building. Although constructed in the 1930s, due to wartime pressures and other projects, it was used only briefly in the 1970s and never fully realized. Recently Robinson Hall has been fully renovated to house the Ronald and Maxine Linde Center for Global Environmental Science. The coelostat operation was modernized replacing the old motors and automating all the motions. Each morning, if the weather cooperates, the dome slit opens, the mirrors configured and sunlight pours into the building. The beam of sunlight is divided into three parts. One part goes into a refracting telescope which projects a ten inch diameter of the sun onto a ground glass screen visible to the public. A second fraction is distributed to fiber optic fixtures that illuminate some of the basement rooms. The final fraction goes into two laboratories where it is used in experiments monitoring trace constituents of our atmosphere and for solar catalysis experiments. The instrument as originally conceived required at least two human operators. Now it is fully automatic and doing real science
Hypernuclear Spectroscopy at JLab Hall C
Hashimoto, Osamu; Doi, Daisuke; Fujii, Yu; Toshiyuki, Gogami; Kanda, Hiroki; Kaneta, M; Kawama, Daisuke; Maeda, Kazushige; Maruta, Tomofumi; Matsumura, Akihiko; Nagao, Sho; Nakamura, Satoshi; Shichijo, Ayako; Tamura, Hirokazu; Taniya, Naotaka; Yamamoto, Taku; Yokota, Kosuke; Kato, S; Sato, Yoshinori; Takahashi, Toshiyuki; Noumi, Hiroyuki; Motoba, T; Hiyama, E; Albayrak, Ibrahim; Ates, Ozgur; Chen, Chunhua; Christy, Michael; Keppel, Cynthia; Kohl, Karl; Li, Ya; Liyanage, Anusha Habarakada; Tang, Liguang; Walton, T; Ye, Zhihong; Yuan, Lulin; Zhu, Lingyan; Baturin, Pavlo; Boeglin, Werner; Dhamija, Seema; Markowitz, Pete; Raue, Brian; Reinhold, Joerg; Hungerford, Ed; Ent, Rolf; Fenker, Howard; Gaskell, David; Horn, Tanja; Jones, Mark; Smith, Gregory; Vulcan, William; Wood, Stephen; Johnston, C; Simicevic, Neven; Wells, Stephen; Samantha, Chhanda; Hu, Bitao; Shen, Ji; Wang, W; Zhang, Xiaozhuo; Zhang, Yi; Feng, Jing; Fu, Y; Zhou, Jian; Zhou, S; Jiang, Yi; Lu, H; Yan, Xinhu; Ye, Yunxiu; Gan, Liping; Ahmidouch, Abdellah; Danagoulian, Samuel; Gasparian, Ashot; Elaasar, Mostafa; Wesselmann, Frank; Asaturyan, Arshak; Margaryan, Amur; Mkrtchyan, Arthur; Mkrtchyan, Hamlet; Tadevosyan, Vardan; Androic, Darko; Furic, Miroslav; Petkovic, Tomislav; Seva, Tomislav; Niculescu, Gabriel; Niculescu, Maria-Ioana; Rodriguez, Victor; Cisbani, Evaristo; Cusanno, Francesco; Garibaldi, Franco; Urciuoli, Guido; De Leo, Raffaele; Maronne, S; Achenbach, Carsten; Pochodzalla, J
2010-03-01
Since the 1st generation experiment, E89-009, which was successfully carried out as a pilot experiment of (e,e'K+) hypernuclear spectroscopy at JLab Hall C in 2000, precision hypernuclear spectroscopy by the (e,e'K+) reactions made considerable progress. It has evolved to the 2nd generation experiment, E01-011, in which a newly constructed high resolution kaon spectrometer (HKS) was installed and the “Tilt method” was adopted in order to suppress large electromagnetic background and to run with high luminosity. Preliminary high-resolution spectra of 7ΛHe and 28ΛAl together with that of 12ΛB that achieved resolution better than 500 keV(FWHM) were obtained. The third generation experiment, E05-115, has completed data taking with an experimental setup combining a new splitter magnet, high resolution electron spectrometer (HES) and the HKS used in the 2nd generation experiment. The data were accumulated with targets of 7Li, 9Be, 10B, 12C and 52Cr as well as with those of CH2 and H2O for calibration. The analysis is under way with particular emphasis of determining precision absolute hypernuclear masses. In this article, hypernuclear spectroscopy program in the wide mass range at JLab Hall C that has undergone three generation is described.
Hall Effect Measured Using a Waveguide Tee
NASA Astrophysics Data System (ADS)
Coppock, Joyce; Anderson, James; Johnson, William
2014-03-01
We describe a simple microwave apparatus to measure the Hall effect in semiconductor wafers. The advantage of this technique is that it does not require contacts on the sample or the use of a resonant cavity. Our method consists of placing the semiconductor wafer into a slot cut in an X-band waveguide tee, which lies in the center of an electromagnet, injecting power into the two opposing arms of the tee, and measuring the output at the third arm. Application of a magnetic field gives a Hall signal that is linear in the magnetic field and which reverses phase when the magnetic field is reversed. This method yields the semiconductor mobility, which we can compare for calibration purposes with mobility data from direct-current (Van der Pauw1) measurements. We are in the process of modeling the system using a finite-difference time-domain (FDTD) simulation to better understand the behavior of the electric fields inside the sample. Resistivity data is obtained by measuring the microwave reflection coefficient of the sample. This talk presents data for silicon and germanium samples doped with boron or phosphorus. Measured mobilities ranged from 270-3000 cm2/V.s . 1L. J. van der Pauw, PhilipsResearchReports 13, 1 (1958)
Cylindrical Hall Thrusters with Permanent Magnets
Raitses, Yevgeny; Merino, Enrique; Fisch, Nathaniel J.
2010-10-18
The use of permanent magnets instead of electromagnet coils for low power Hall thrusters can offer a significant reduction of both the total electric power consumption and the thruster mass. Two permanent magnet versions of the miniaturized cylindrical Hall thruster (CHT) of different overall dimensions were operated in the power range of 50W-300 W. The discharge and plasma plume measurements revealed that the CHT thrusters with permanent magnets and electromagnet coils operate rather differently. In particular, the angular ion current density distribution from the permanent magnet thrusters has an unusual halo shape, with a majority of high energy ions flowing at large angles with respect to the thruster centerline. Differences in the magnetic field topology outside the thruster channel and in the vicinity of the channel exit are likely responsible for the differences in the plume characteristics measured for the CHTs with electromagnets and permanent magnets. It is shown that the presence of the reversing-direction or cusp-type magnetic field configuration inside the thruster channel without a strong axial magnetic field outside the thruster channel does not lead to the halo plasma plume from the CHT. __________________________________________________
Spin Hall Magnetoresistance in Metallic Bilayers.
Kim, Junyeon; Sheng, Peng; Takahashi, Saburo; Mitani, Seiji; Hayashi, Masamitsu
2016-03-01
Spin Hall magnetoresistance (SMR) is studied in metallic bilayers that consist of a heavy metal (HM) layer and a ferromagnetic metal (FM) layer. We find a nearly tenfold increase of SMR in W/CoFeB compared to previously studied HM/ferromagnetic insulator systems. The SMR increases with decreasing temperature despite the negligible change in the W layer resistivity. A model is developed to account for the absorption of the longitudinal spin current to the FM layer, one of the key characteristics of a metallic ferromagnet. We find that the model not only quantitatively describes the HM layer thickness dependence of SMR, allowing accurate estimation of the spin Hall angle and the spin diffusion length of the HM layer, but also can account for the temperature dependence of SMR by assuming a temperature dependent spin polarization of the FM layer. These results illustrate the unique role a metallic ferromagnetic layer plays in defining spin transmission across the HM/FM interface. PMID:26991195
Undulator Hall Air Temperature Fault Scenarios
Sevilla, J.; Welch, J.; /SLAC
2010-11-17
Recent experience indicates that the LCLS undulator segments must not, at any time following tuning, be allowed to change temperature by more than about {+-}2.5 C or the magnetic center will irreversibly shift outside of acceptable tolerances. This vulnerability raises a concern that under fault conditions the ambient temperature in the Undulator Hall might go outside of the safe range and potentially could require removal and retuning of all the segments. In this note we estimate changes that can be expected in the Undulator Hall air temperature for three fault scenarios: (1) System-wide power failure; (2) Heating Ventilation and Air Conditioning (HVAC) system shutdown; and (3) HVAC system temperature regulation fault. We find that for either a system-wide power failure or an HVAC system shutdown (with the technical equipment left on), the short-term temperature changes of the air would be modest due to the ability of the walls and floor to act as a heat ballast. No action would be needed to protect the undulator system in the event of a system-wide power failure. Some action to adjust the heat balance, in the case of the HVAC power failure with the equipment left on, might be desirable but is not required. On the other hand, a temperature regulation failure of the HVAC system can quickly cause large excursions in air temperature and prompt action would be required to avoid damage to the undulator system.
Geometry of Fractional Quantum Hall Fluids
NASA Astrophysics Data System (ADS)
Cho, Gil Young
2015-03-01
Fractional quantum Hall (FQH) fluids of two-dimensional electron gases (2DEG) in large magnetic fields are fascinating topological states of matter. As such they are characterized by universal properties such as their fractional quantum Hall conductivity, fractionally charged anyonic excitations and a degeneracy of topological origin on surfaces with the topology of a torus. Quite surprisingly these topological fluids also couple to the geometry on which the 2DEG resides and have universal responses to adiabatic changes in the geometry. These responses are given by a Wen-Zee term (which describes the coupling of the currents to the spin connection of the geometry) and a gravitational Chern-Simons term which reflects the universal energy and momentum transport along the edges of the FQH state. We use a field theory of the FQH states to derive these universal responses. To account for the coupling to the background geometry, we show that the concept of flux attachment needs to be modified and use it to derive the geometric responses from Chern-Simons theories. We show that the resulting composite particles minimally couple to the spin connection of the geometry. Taking account of the framing anomaly of the quantum Chern-Simons theories, we derive a consistent theory of geometric responses from the Chern-Simons effective field theories and from parton constructions, and apply it to both abelian and non-abelian states. This work was supported in part by the NSF Grant DMR-1408713.
Critical currents of ideal quantum Hall superfluids
NASA Astrophysics Data System (ADS)
Abolfath, M.; MacDonald, A. H.; Radzihovsky, Leo
2003-10-01
Filling factor ν=1 bilayer electron systems in the quantum Hall regime have an excitonic-condensate superfluid ground state when the layer separation d is less than a critical value dc. On a quantum Hall plateau current injected and removed through one of the two layers drives a dissipationless edge current that carries parallel currents and a dissipationless bulk supercurrent that carries opposing currents in the two layers. In this paper we discuss the theory of finite supercurrent bilayer states, both in the presence and in the absence of symmetry breaking interlayer hybridization. Solutions to the microscopic mean-field equations exist at all condensate phase winding rates for zero and sufficiently weak hybridization strengths. We find, however, that collective instabilities occur when the supercurrent exceeds a critical value determined primarily by a competition between direct and exchange interlayer Coulomb interactions. The critical current is estimated using a local stability criterion and varies as (dc-d)1/2 when d approaches dc from below. For large interlayer hybridization, we find that the critical current is limited by a soliton instability of microscopic origin.
A Preliminary Investigation of Hall Thruster Technology
NASA Technical Reports Server (NTRS)
Gallimore, Alec D.
1997-01-01
A three-year NASA/BMDO-sponsored experimental program to conduct performance and plume plasma property measurements on two Russian Stationary Plasma Thrusters (SPTs) has been completed. The program utilized experimental facilitates at the University of Michigan's Plasmadynamics and Electric Propulsion Laboratory (PEPL). The main features of the proposed effort were as follows: (1) Characterized Hall thruster (and arcjet) performance by measuring ion exhaust velocity with probes at various thruster conditions; (2) Used a variety of probe diagnostics in the thruster plume to measure plasma properties and flow properties including T(sub e) and n(sub e) ion current density and ion energy distribution, and electric fields by mapping plasma potential; (3) Used emission spectroscopy to identify species within the plume and to measure electron temperatures. A key and unique feature of our research was our collaboration with Russian Hall thruster researcher Dr. Sergey A Khartov, Deputy Dean of International Relations at the Moscow Aviation Institute (MAI). His activities in this program included consulting on and participation in research at PEPL through use of a MAI-built SPT and ion energy probe.
Interpolation of Hall probe calibration data
Carnegie, D.W.
1992-07-23
Calibrated Hall-effect magnetic-field sensors will be used to map the magnetic field in insertion devices. Typical calibration data give the magnetic field as a function of measured signal and temperature on a two-dimensional grid. We need to calculate the magnetic field from the two measured signals. As an example, this work uses the calibration data supplied with a Hall-effect measurement system from Group 3 Technology Ltd. Detailed field-versus-signal data are given for three calibration temperatures for each of four gain settings. Two methods for performing the interpolation are presented for a fixed gain setting. The first method fits the three field-versus-signal data sets to three polynomials minimizing the sum of squares of the errors and then interpolates for the temperature. The second method uses a bivariate interpolation routine. In this method, there are no residual errors at the calibration points. The two methods are compared. The selection of the method used will depend on what errors are present in the calibration data.
Theoretical Studies in Nuclear Physics. [Oregon State Univ. , Corvallis, Oregon
Landau, R.H.; Madsen, V.A.
1992-01-01
Work in nuclear structure and reaction theory, specifically, the relation of reactions to the nuclear structure. Other work was in intermediate energy physics, few-body problems, and computational physics that heavy ions can be used to measure simultaneously both neutron and proton multipole matrix elements of the target nucleus has added new interest to this area of nuclear structure. Considerable attention to the is therefore paid to the to the methods for calculating multiple matrix elements.
Corvallis 509J T.M.R. Curriculum. Revised Edition.
ERIC Educational Resources Information Center
Beckham, Tass; And Others
Intended for use with trainable retarded, moderately to profoundly multihandicapped students, and young mildly handicapped learners, the curriculum guide provides task objectives, task analyses, and exercise ideas for six categories: self help skills, language skills, motor development skills, basic academic skills, home living skills, and…
Unconventional quantum Hall effect in Floquet topological insulators.
Tahir, M; Vasilopoulos, P; Schwingenschlögl, U
2016-09-28
We study an unconventional quantum Hall effect for the surface states of ultrathin Floquet topological insulators in a perpendicular magnetic field. The resulting band structure is modified by photon dressing and the topological property is governed by the low-energy dynamics of a single surface. An exchange of symmetric and antisymmetric surface states occurs by reversing the light's polarization. We find a novel quantum Hall state in which the zeroth Landau level undergoes a phase transition from a trivial insulator state, with Hall conductivity [Formula: see text] at zero Fermi energy, to a Hall insulator state with [Formula: see text]. These findings open new possibilities for experimentally realizing nontrivial quantum states and unusual quantum Hall plateaus at [Formula: see text].
Magnetic Measurement of the Background Field in the Undulator Hall
Fisher, Andrew; Nuhn, Heinz-Dieter; Welch, James; /SLAC
2010-11-18
The steel present in the construction of the undulator hall facility has the potential for changing the ambient fields present in the undulator hall. This note describes a measurement done to make a comparison between the fields in the hall and in the Magnetic Measurement Facility. In order for the undulators to have the proper tuning, the background magnetic field in the Undulator Hall should agree with the background field in the Magnetic Measurements Facility within .5 gauss. In order to verify that this was the case measurements were taken along the length of the undulator hall, and the point measurements were compared to the mean field which was measured on the MMF test bench.
Anomalous Hall effect in YIG|Pt bilayers
Meyer, Sibylle Schlitz, Richard; Geprägs, Stephan; Opel, Matthias; Huebl, Hans; Goennenwein, Sebastian T. B.; Gross, Rudolf
2015-03-30
We measure the ordinary and the anomalous Hall effect in a set of yttrium iron garnet|platinum (YIG|Pt) bilayers via magnetization orientation dependent magnetoresistance experiments. Our data show that the presence of the ferrimagnetic insulator YIG leads to an anomalous Hall effect like voltage in Pt, which is sensitive to both Pt thickness and temperature. Interpretation of the experimental findings in terms of the spin Hall anomalous Hall effect indicates that the imaginary part of the spin mixing conductance G{sub i} plays a crucial role in YIG|Pt bilayers. In particular, our data suggest a sign change in G{sub i} between 10 K and 300 K. Additionally, we report a higher order Hall effect contribution, which appears in thin Pt films on YIG at low temperatures.
Unconventional quantum Hall effect in Floquet topological insulators.
Tahir, M; Vasilopoulos, P; Schwingenschlögl, U
2016-09-28
We study an unconventional quantum Hall effect for the surface states of ultrathin Floquet topological insulators in a perpendicular magnetic field. The resulting band structure is modified by photon dressing and the topological property is governed by the low-energy dynamics of a single surface. An exchange of symmetric and antisymmetric surface states occurs by reversing the light's polarization. We find a novel quantum Hall state in which the zeroth Landau level undergoes a phase transition from a trivial insulator state, with Hall conductivity [Formula: see text] at zero Fermi energy, to a Hall insulator state with [Formula: see text]. These findings open new possibilities for experimentally realizing nontrivial quantum states and unusual quantum Hall plateaus at [Formula: see text]. PMID:27460419
Anomalous resistance overshoot in the integer quantum Hall effect
Kendirlik, E. M.; Sirt, S.; Kalkan, S. B.; Dietsche, W.; Wegscheider, W.; Ludwig, S.; Siddiki, A.
2013-01-01
In this work we report on experiments performed on smooth edge-narrow Hall bars. The magneto-transport properties of intermediate mobility two-dimensional electron systems are investigated and analyzed within the screening theory of the integer quantized Hall effect. We observe a non-monotonic increase of Hall resistance at the low magnetic field ends of the quantized plateaus, known as the overshoot effect. Unexpectedly, for Hall bars that are defined by shallow chemical etching the overshoot effect becomes more pronounced at elevated temperatures. We observe the overshoot effect at odd and even integer plateaus, which favor a spin independent explanation, in contrast to discussion in the literature. In a second set of the experiments, we investigate the overshoot effect in gate defined Hall bar and explicitly show that the amplitude of the overshoot effect can be directly controlled by gate voltages. We offer a comprehensive explanation based on scattering between evanescent incompressible channels. PMID:24190162
Quantifying spin Hall angles from spin pumping: experiments and theory.
Mosendz, O; Pearson, J E; Fradin, F Y; Bauer, G E W; Bader, S D; Hoffmann, A
2010-01-29
Spin Hall effects intermix spin and charge currents even in nonmagnetic materials and, therefore, ultimately may allow the use of spin transport without the need for ferromagnets. We show how spin Hall effects can be quantified by integrating Ni{80}Fe{20}|normal metal (N) bilayers into a coplanar waveguide. A dc spin current in N can be generated by spin pumping in a controllable way by ferromagnetic resonance. The transverse dc voltage detected along the Ni{80}Fe{20}|N has contributions from both the anisotropic magnetoresistance and the spin Hall effect, which can be distinguished by their symmetries. We developed a theory that accounts for both. In this way, we determine the spin Hall angle quantitatively for Pt, Au, and Mo. This approach can readily be adapted to any conducting material with even very small spin Hall angles.
Anomalous resistance overshoot in the integer quantum Hall effect.
Kendirlik, E M; Sirt, S; Kalkan, S B; Dietsche, W; Wegscheider, W; Ludwig, S; Siddiki, A
2013-01-01
In this work we report on experiments performed on smooth edge-narrow Hall bars. The magneto-transport properties of intermediate mobility two-dimensional electron systems are investigated and analyzed within the screening theory of the integer quantized Hall effect. We observe a non-monotonic increase of Hall resistance at the low magnetic field ends of the quantized plateaus, known as the overshoot effect. Unexpectedly, for Hall bars that are defined by shallow chemical etching the overshoot effect becomes more pronounced at elevated temperatures. We observe the overshoot effect at odd and even integer plateaus, which favor a spin independent explanation, in contrast to discussion in the literature. In a second set of the experiments, we investigate the overshoot effect in gate defined Hall bar and explicitly show that the amplitude of the overshoot effect can be directly controlled by gate voltages. We offer a comprehensive explanation based on scattering between evanescent incompressible channels.
Unconventional quantum Hall effect in Floquet topological insulators
NASA Astrophysics Data System (ADS)
Tahir, M.; Vasilopoulos, P.; Schwingenschlögl, U.
2016-09-01
We study an unconventional quantum Hall effect for the surface states of ultrathin Floquet topological insulators in a perpendicular magnetic field. The resulting band structure is modified by photon dressing and the topological property is governed by the low-energy dynamics of a single surface. An exchange of symmetric and antisymmetric surface states occurs by reversing the light’s polarization. We find a novel quantum Hall state in which the zeroth Landau level undergoes a phase transition from a trivial insulator state, with Hall conductivity {σyx}=0 at zero Fermi energy, to a Hall insulator state with {σyx}={{e}2}/2h . These findings open new possibilities for experimentally realizing nontrivial quantum states and unusual quantum Hall plateaus at (+/- 1/2,+/- 3/2,+/- 5/2,...){{e}2}/h .
Construction and Operation of a Differential Hall Element Magnetometer
NASA Astrophysics Data System (ADS)
Calkins, Matthew W.; Javernick, Philip D.; Quintero, Pedro A.; Calm, Yitzi M.; Meisel, Mark W.
2012-02-01
A Differential Hall Element Magnetometer (DHEM) was constructed to measure the magnetic saturation and coercive fields of small samples consisting of magnetic nanoparticles that may have biomedical applications. The device consists of two matched Hall elements that can be moved through the room temperature bore of a 9 Tesla superconducting magnet. The Hall elements are wired in opposition such that a null response, to within a small offset, is measured in the absence of a sample that may be located on top of one unit. A LabVIEW program controls the current through the Hall elements and measures the net Hall voltage while simultaneously moving the probe through the magnetic field by regulating a linear stepper motor. Ultimately, the system will be tested to obtain a figure of merit using successively smaller samples. Details of the apparatus will be provided along with preliminary data.
Agricultural Education at Risk.
ERIC Educational Resources Information Center
Evans, Donald E.
1988-01-01
Discusses educational reform in the context of agricultural education. Covers a recent report on agricultural education reform by the National Academy of Sciences, state legislative initiatives, and several recommendations for the future of agricultural education. (CH)
Lee, E.H.; Tingey, D.T.; Hogsett, W.E.
1989-06-01
This report evaluates ambient air quality indicators for ozone (O{sub 3}) and estimates the exposure levels associated with agricultural losses. In support of the U.S. EPA Office of Air Quality Planning and Standards review and evaluation of a secondary National Ambient Air Quality Standard for ozone, the Terrestrial Branch within the Corvallis Environmental Research Laboratory investigated alternative exposure indices for characterizing the adverse effects of ozone on agriculture, using experimental data from the National Crop Loss Assessment Network program. Scientific and technical information on ozone and its effects on vegetation, natural ecosystems, natural and artificial materials, and human welfare necessitates a secondary standard that adequately describes the temporal variations of exposure and their effects on plant production and correlates well with short- and long-term exposures. The identification of an appropriate ozone standard that protects against crop-yield losses proceeds along two lines: regression analysis of plant response data against various exposure indices to determine indices that best depict biological response, and ambient air quality analysis of ambient O{sub 3} data to identify indices that correlate well with various exposure patterns.
Quantum anomalous Hall and quantum spin-Hall phases in flattened Bi and Sb bilayers
Jin, Kyung-Hwan; Jhi, Seung-Hoon
2015-01-01
Discovery of two-dimensional topological insulator such as Bi bilayer initiates challenges in exploring exotic quantum states in low dimensions. We demonstrate a promising way to realize the Kane-Mele-type quantum spin Hall (QSH) phase and the quantum anomalous Hall (QAH) phase in chemically-modified Bi and Sb bilayers using first-principles calculations. We show that single Bi and Sb bilayers exhibit topological phase transitions from the band-inverted QSH phase or the normal insulator phase to Kane-Mele-type QSH phase upon chemical functionalization. We also predict that the QAH effect can be induced in Bi or Sb bilayers upon nitrogen deposition as checked from calculated Berry curvature and the Chern number. We explicitly demonstrate the spin-chiral edge states to appear in nitrogenated Bi-bilayer nanoribbons. PMID:25672932
75 FR 26918 - Siuslaw Resource Advisory Committee
Federal Register 2010, 2011, 2012, 2013, 2014
2010-05-13
...; ] DEPARTMENT OF AGRICULTURE Forest Service Siuslaw Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The Siuslaw Resource Advisory Committee will meet in Corvallis,...
Electromagnetic interactions in quantum Hall ferromagnets
Ray, Rashmi
1998-11-10
The {nu}=1 quantum Hall ground state in materials like GaAs is known to be ferromagnetic in nature. The exchange part of the Coulomb interaction provides the required attractive force to align the electronic spins spontaneously. The gapless Goldstone modes are the angular deviations of the magnetization vector from its fixed ground state orientation. Furthermore, the system supports electrically charged spin skyrmion configurations. It has been claimed in the literature that these skyrmions have half-integral spin owing to the presence of a topological Hopf term in the effective action governing the spin excitations. However, it has also been claimed that the derivation leading to this term is somewhat flawed. In this article, we demonstrate the existence of this term unambiguously. Furthermore, we investigate the electromagnetic interactions of the spin excitations and obtain a compact expression for the leading nonminimal electromagnetic coupling of these degrees of freedom.
Mesoscopic spin Hall effect in semiconductor nanostructures
NASA Astrophysics Data System (ADS)
Zarbo, Liviu
The spin Hall effect (SHE) is a name given to a collection of diverse phenomena which share two principal features: (i) longitudinal electric current flowing through a paramagnetic semiconductor or metallic sample leads to transverse spin current and spin accumulation of opposite sign at opposing lateral edges; (ii) SHE does not require externally applied magnetic field or magnetic ordering in the equilibrium state of the sample, instead it relies on the presence of spin-orbit (SO) couplings within the sample. This thesis elaborates on a new type of phenomenon within the SHE family, predicted in our recent studies [Phys. Rev. B 72, 075361 (2005); Phys. Rev. Lett. 95, 046601 (2005); Phys. Rev. B 72, 075335 (2005); Phys. Rev. B 73 , 075303 (2006); and Europhys. Lett. 77, 47004 (2007)], where pure spin current flows through the transverse electrodes attached to a clean finitesize two-dimensional electron gas (2DEG) due to unpolarized charge current injected through its longitudinal leads. If transverse leads are removed, the effect manifests as nonequilibrium spin Hall accumulation at the lateral edges of 2DEG wires. The SO coupling driving this SHE effect is of the Rashba type, which arises due to structural inversion asymmetry of semiconductor heterostructure hosting the 2DEG. We term the effect "mesoscopic" because the spin Hall currents and accumulations reach optimal value in samples of the size of the spin precession length---the distance over which the spin of an electron precesses by an angle pi. In strongly SO-coupled structures this scale is of the order of ˜100 nm, and, therefore, mesoscopic in the sense of being much larger than the characteristic microscopic scales (such as the Fermi wavelength, screening length, or the mean free path in disordered systems), but still much smaller than the macroscopic ones. Although the first theoretical proposal for SHE, driven by asymmetry in SO-dependent scattering of spin-up and spin-down electrons off impurities
Spin Hall phenomenology of magnetic dynamics
NASA Astrophysics Data System (ADS)
Tserkovnyak, Yaroslav; Bender, Scott A.
2014-07-01
We study the role of spin-orbit interactions in the coupled magnetoelectric dynamics of a ferromagnetic film coated with an electrical conductor. While the main thrust of this work is phenomenological, several popular simple models are considered microscopically in some detail, including Rashba and Dirac two-dimensional electron gases coupled to a magnetic insulator, as well as a diffusive spin Hall system. We focus on the long-wavelength magnetic dynamics that experiences current-induced torques and produces fictitious electromotive forces. Our phenomenology provides a suitable framework for analyzing experiments on current-induced magnetic dynamics and reciprocal charge pumping, including the effects of magnetoresistance and Gilbert-damping anisotropies, without a need to resort to any microscopic considerations or modeling. Finally, some remarks are made regarding the interplay of spin-orbit interactions and magnetic textures.
Gauge Physics of Spin Hall Effect
Tan, Seng Ghee; Jalil, Mansoor B. A.; Ho, Cong Son; Siu, Zhuobin; Murakami, Shuichi
2015-01-01
Spin Hall effect (SHE) has been discussed in the context of Kubo formulation, geometric physics, spin orbit force, and numerous semi-classical treatments. It can be confusing if the different pictures have partial or overlapping claims of contribution to the SHE. In this article, we present a gauge-theoretic, time-momentum elucidation, which provides a general SHE equation of motion, that unifies under one theoretical framework, all contributions of SHE conductivity due to the kinetic, the spin orbit force (Yang-Mills), and the geometric (Murakami-Fujita) effects. Our work puts right an ambiguity surrounding previously partial treatments involving the Kubo, semiclassical, Berry curvatures, or the spin orbit force. Our full treatment shows the Rashba 2DEG SHE conductivity to be instead of −, and Rashba heavy hole instead of −. This renewed treatment suggests a need to re-derive and re-calculate previously studied SHE conductivity. PMID:26689260
Layered quantum Hall insulators with ultracold atoms
Zamora, A.; Szirmai, G.; Lewenstein, M.
2011-11-15
We consider a generalization of the two-dimensional (2D) quantum Hall insulator to a noncompact, non-Abelian gauge group, the Heisenberg-Weyl group. We show that this kind of insulator is actually a layered three-dimensional (3D) insulator with nontrivial topology. We further show that nontrivial combinations of quantized transverse conductivities can be engineered with the help of a staggered potential. We investigate the robustness and topological nature of this conductivity and connect it to the surface modes of the system. We also propose a simple experimental realization with ultracold atoms in 3D confined to a 2D square lattice with the third dimension being mapped to a gauge coordinate.
Photonic spin Hall effect at metasurfaces.
Yin, Xiaobo; Ye, Ziliang; Rho, Junsuk; Wang, Yuan; Zhang, Xiang
2013-03-22
The spin Hall effect (SHE) of light is very weak because of the extremely small photon momentum and spin-orbit interaction. Here, we report a strong photonic SHE resulting in a measured large splitting of polarized light at metasurfaces. The rapidly varying phase discontinuities along a metasurface, breaking the axial symmetry of the system, enable the direct observation of large transverse motion of circularly polarized light, even at normal incidence. The strong spin-orbit interaction deviates the polarized light from the trajectory prescribed by the ordinary Fermat principle. Such a strong and broadband photonic SHE may provide a route for exploiting the spin and orbit angular momentum of light for information processing and communication.
OPTICS. Quantum spin Hall effect of light.
Bliokh, Konstantin Y; Smirnova, Daria; Nori, Franco
2015-06-26
Maxwell's equations, formulated 150 years ago, ultimately describe properties of light, from classical electromagnetism to quantum and relativistic aspects. The latter ones result in remarkable geometric and topological phenomena related to the spin-1 massless nature of photons. By analyzing fundamental spin properties of Maxwell waves, we show that free-space light exhibits an intrinsic quantum spin Hall effect—surface modes with strong spin-momentum locking. These modes are evanescent waves that form, for example, surface plasmon-polaritons at vacuum-metal interfaces. Our findings illuminate the unusual transverse spin in evanescent waves and explain recent experiments that have demonstrated the transverse spin-direction locking in the excitation of surface optical modes. This deepens our understanding of Maxwell's theory, reveals analogies with topological insulators for electrons, and offers applications for robust spin-directional optical interfaces. PMID:26113717
Gauge Physics of Spin Hall Effect.
Tan, Seng Ghee; Jalil, Mansoor B A; Ho, Cong Son; Siu, Zhuobin; Murakami, Shuichi
2015-12-22
Spin Hall effect (SHE) has been discussed in the context of Kubo formulation, geometric physics, spin orbit force, and numerous semi-classical treatments. It can be confusing if the different pictures have partial or overlapping claims of contribution to the SHE. In this article, we present a gauge-theoretic, time-momentum elucidation, which provides a general SHE equation of motion, that unifies under one theoretical framework, all contributions of SHE conductivity due to the kinetic, the spin orbit force (Yang-Mills), and the geometric (Murakami-Fujita) effects. Our work puts right an ambiguity surrounding previously partial treatments involving the Kubo, semiclassical, Berry curvatures, or the spin orbit force. Our full treatment shows the Rashba 2DEG SHE conductivity to be [formula in text] instead of [formula in text], and Rashba heavy hole [formula in text] instead of [formula in text]. This renewed treatment suggests a need to re-derive and re-calculate previously studied SHE conductivity.
Gauge Physics of Spin Hall Effect
NASA Astrophysics Data System (ADS)
Tan, Seng Ghee; Jalil, Mansoor B. A.; Ho, Cong Son; Siu, Zhuobin; Murakami, Shuichi
2015-12-01
Spin Hall effect (SHE) has been discussed in the context of Kubo formulation, geometric physics, spin orbit force, and numerous semi-classical treatments. It can be confusing if the different pictures have partial or overlapping claims of contribution to the SHE. In this article, we present a gauge-theoretic, time-momentum elucidation, which provides a general SHE equation of motion, that unifies under one theoretical framework, all contributions of SHE conductivity due to the kinetic, the spin orbit force (Yang-Mills), and the geometric (Murakami-Fujita) effects. Our work puts right an ambiguity surrounding previously partial treatments involving the Kubo, semiclassical, Berry curvatures, or the spin orbit force. Our full treatment shows the Rashba 2DEG SHE conductivity to be instead of -, and Rashba heavy hole instead of -. This renewed treatment suggests a need to re-derive and re-calculate previously studied SHE conductivity.
Level statistics for quantum Hall systems
NASA Astrophysics Data System (ADS)
Kagalovsky, V.; Horovitz, B.; Avishai, Y.
2005-03-01
Level statistics for two classes of disordered systems at criticality are analyzed in terms of different realizations of the Chalker-Coddington network model. These include: 1) Re-examination of the standard U(1) model describing dynamics of electrons on the lowest Landau level in the quantum Hall effect, where it is shown that after proper local unfolding the nearest-neighbor spacing distribution (NNSD) at the critical energy follows the Wigner surmise for Gaussian unitary ensembles (GUE). 2) Quasi-particles in disordered superconductors with broken time reversal and spin rotation invariance (in the language of random matrix theory this system is a representative of symmetry class D in the classification scheme of Altland and Zirnbauer). Here again the NNSD obeys the Wigner surmise for GUE, reflecting therefore only "basic" discrete symmetries of the system (time reversal violation) and ignoring particle-hole symmetries and other finer details (criticality). In the localized regime level repulsion is suppressed.
OPTICS. Quantum spin Hall effect of light.
Bliokh, Konstantin Y; Smirnova, Daria; Nori, Franco
2015-06-26
Maxwell's equations, formulated 150 years ago, ultimately describe properties of light, from classical electromagnetism to quantum and relativistic aspects. The latter ones result in remarkable geometric and topological phenomena related to the spin-1 massless nature of photons. By analyzing fundamental spin properties of Maxwell waves, we show that free-space light exhibits an intrinsic quantum spin Hall effect—surface modes with strong spin-momentum locking. These modes are evanescent waves that form, for example, surface plasmon-polaritons at vacuum-metal interfaces. Our findings illuminate the unusual transverse spin in evanescent waves and explain recent experiments that have demonstrated the transverse spin-direction locking in the excitation of surface optical modes. This deepens our understanding of Maxwell's theory, reveals analogies with topological insulators for electrons, and offers applications for robust spin-directional optical interfaces.
Quantum depinning transition of quantum Hall stripes.
Li, M-R; Fertig, H A; Côté, R; Yi, Hangmo
2004-05-01
We examine the effect of disorder on the electromagnetic response of quantum Hall stripes using an effective elastic theory to describe their low-energy dynamics, and replicas and the Gaussian variational method to handle disorder effects. Within our model we demonstrate the existence of a depinning transition at a critical partial Landau level filling factor Deltanu(c). For Deltanu
A Preliminary Investigation of Hall Thruster Technology
NASA Technical Reports Server (NTRS)
Gallimore, Alec D.
1997-01-01
A three-year, NASA/BMDO-sponsored experimental program to conduct performance and plume plasma property measurements on two Russian Stationary Plasma Thrusters (SPTs) has been completed. The program utilized experimental facilitates at the University of Michigan's Plasmadynamics and Electric Propulsion Laboratory (PEPL). The main features of the proposed effort were as follows: We Characterized Hall thruster [and arcjet] performance by measuring ion exhaust velocity with probes at various thruster conditions. Used a variety of probe diagnostics in the thruster plume to measure plasma properties and flow properties including T(sub e) and n(sub e), ion current density and ion energy distribution, and electric fields by mapping plasma potential. Used emission spectroscopy to identify species within the plume and to measure electron temperatures.
Quantum spin Hall effect of light
NASA Astrophysics Data System (ADS)
Bliokh, Konstantin Y.; Smirnova, Daria; Nori, Franco
2015-06-01
Maxwell’s equations, formulated 150 years ago, ultimately describe properties of light, from classical electromagnetism to quantum and relativistic aspects. The latter ones result in remarkable geometric and topological phenomena related to the spin-1 massless nature of photons. By analyzing fundamental spin properties of Maxwell waves, we show that free-space light exhibits an intrinsic quantum spin Hall effect—surface modes with strong spin-momentum locking. These modes are evanescent waves that form, for example, surface plasmon-polaritons at vacuum-metal interfaces. Our findings illuminate the unusual transverse spin in evanescent waves and explain recent experiments that have demonstrated the transverse spin-direction locking in the excitation of surface optical modes. This deepens our understanding of Maxwell’s theory, reveals analogies with topological insulators for electrons, and offers applications for robust spin-directional optical interfaces.
Magnetic circuit for hall effect plasma accelerator
NASA Technical Reports Server (NTRS)
Manzella, David H. (Inventor); Jacobson, David T. (Inventor); Jankovsky, Robert S. (Inventor); Hofer, Richard (Inventor); Peterson, Peter (Inventor)
2009-01-01
A Hall effect plasma accelerator includes inner and outer electromagnets, circumferentially surrounding the inner electromagnet along a thruster centerline axis and separated therefrom, inner and outer magnetic conductors, in physical connection with their respective inner and outer electromagnets, with the inner magnetic conductor having a mostly circular shape and the outer magnetic conductor having a mostly annular shape, a discharge chamber, located between the inner and outer magnetic conductors, a magnetically conducting back plate, in magnetic contact with the inner and outer magnetic conductors, and a combined anode electrode/gaseous propellant distributor, located at a bottom portion of the discharge chamber. The inner and outer electromagnets, the inner and outer magnetic conductors and the magnetically conducting back plate form a magnetic circuit that produces a magnetic field that is largely axial and radially symmetric with respect to the thruster centerline.
Hall effect in a moving liquid
NASA Astrophysics Data System (ADS)
Di Lieto, Alberto; Giuliano, Alessia; Maccarrone, Francesco; Paffuti, Giampiero
2012-01-01
A simple experiment, suitable for performing in an undergraduate physics laboratory, illustrates electromagnetic induction through the water entering into a cylindrical rubber tube by detecting the voltage developed across the tube in the direction transverse both to the flow velocity and to the magnetic field. The apparatus is a very simple example of an electromagnetic flowmeter, a device which is commonly used both in industrial and physiological techniques. The phenomenology observed is similar to that of the Hall effect in the absence of an electric current in the direction of motion of the carriers. The experimental results show a dependence on the intensity of the magnetic field and on the carrier velocity, in good agreement with the theory. Discussion of the system, based on classical electromagnetism, indicates that the effect depends only on the flow rate, and is independent both of the velocity profile and of the electrical conductivity of the medium.
Terahertz Antiferromagnetic Spin Hall Nano-Oscillator
NASA Astrophysics Data System (ADS)
Cheng, Ran; Xiao, Di; Brataas, Arne
2016-05-01
We consider the current-induced dynamics of insulating antiferromagnets in a spin Hall geometry. Sufficiently large in-plane currents perpendicular to the Néel order trigger spontaneous oscillations at frequencies between the acoustic and the optical eigenmodes. The direction of the driving current determines the chirality of the excitation. When the current exceeds a threshold, the combined effect of spin pumping and current-induced torques introduces a dynamic feedback that sustains steady-state oscillations with amplitudes controllable via the applied current. The ac voltage output is calculated numerically as a function of the dc current input for different feedback strengths. Our findings open a route towards terahertz antiferromagnetic spin-torque oscillators.
Cathode Effects in Cylindrical Hall Thrusters
Granstedt, E.M.; Raitses, Y.; Fisch, N. J.
2008-09-12
Stable operation of a cylindrical Hall thruster (CHT) has been achieved using a hot wire cathode, which functions as a controllable electron emission source. It is shown that as the electron emission from the cathode increases with wire heating, the discharge current increases, the plasma plume angle reduces, and the ion energy distribution function shifts toward higher energies. The observed effect of cathode electron emission on thruster parameters extends and clarifies performance improvements previously obtained for the overrun discharge current regime of the same type of thruster, but using a hollow cathode-neutralizer. Once thruster discharge current saturates with wire heating, further filament heating does not affect other discharge parameters. The saturated values of thruster discharge parameters can be further enhanced by optimal placement of the cathode wire with respect to the magnetic field.
50 KW Class Krypton Hall Thruster Performance
NASA Technical Reports Server (NTRS)
Jacobson, David T.; Manzella, David H.
2003-01-01
The performance of a 50-kilowatt-class Hall thruster designed for operation on xenon propellant was measured using kryton propellant. The thruster was operated at discharge power levels ranging from 6.4 to 72.5 kilowatts. The device produced thrust ranging from 0.3 to 2.5 newtons. The thruster was operated at discharge voltages between 250 and 1000 volts. At the highest anode mass flow rate and discharge voltage and assuming a 100 percent singly charged condition, the discharge specific impulse approached the theoretical value. Discharge specific impulse of 4500 seconds was demonstrated at a discharge voltage of 1000 volts. The peak discharge efficiency was 64 percent at 650 volts.
Spin Hall magnetoresistance at high temperatures
Uchida, Ken-ichi; Qiu, Zhiyong; Kikkawa, Takashi; Iguchi, Ryo; Saitoh, Eiji
2015-02-02
The temperature dependence of spin Hall magnetoresistance (SMR) in Pt/Y{sub 3}Fe{sub 5}O{sub 12} (YIG) bilayer films has been investigated in a high temperature range from room temperature to near the Curie temperature of YIG. The experimental results show that the magnitude of the magnetoresistance ratio induced by the SMR monotonically decreases with increasing the temperature and almost disappears near the Curie temperature. We found that, near the Curie temperature, the temperature dependence of the SMR in the Pt/YIG film is steeper than that of a magnetization curve of the YIG; the critical exponent of the magnetoresistance ratio is estimated to be 0.9. This critical behavior of the SMR is attributed mainly to the temperature dependence of the spin-mixing conductance at the Pt/YIG interface.
Quantized topological Hall effect in skyrmion crystal
NASA Astrophysics Data System (ADS)
Hamamoto, Keita; Ezawa, Motohiko; Nagaosa, Naoto
2015-09-01
We theoretically study the quantized topological Hall effect (QTHE) in skyrmion crystal (SkX) without external magnetic field. The emergent magnetic field in SkX could be gigantic, as much as 4000 T , when its lattice constant is 1 nm . The band structure is not flat but has a finite gap in the low electron-density regime. We also study the conditions to realize the QTHE for the skyrmion size, carrier density, disorder strength, and temperature. Comparing the SkX and the system under the corresponding uniform magnetic field, the former is more fragile against the temperature compared with the latter since the gap is reduced by a factor of 1/5, while they are almost equally robust against the disorder. Therefore, it is expected that the QTHE of the SkX system is realized even with strong disorder at room temperature when the electron density is of the order of 1 per skyrmion.
Hall MHD Equilibrium of Accelerated Compact Toroids
NASA Astrophysics Data System (ADS)
Howard, S. J.; Hwang, D. Q.; Horton, R. D.; Evans, R. W.; Brockington, S. J.
2007-11-01
We examine the structure and dynamics of the compact toroid's magnetic field. The compact toroid is dramatically accelerated by a large rail-gun Lorentz force density equal to j xB. We use magnetic data from the Compact Toroid Injection Experiment to answer the question of exactly where in the system j xB has nonzero values, and to what extent we can apply the standard model of force-free equilibrium. In particular we present a method of analysis of the magnetic field probe signals that allows direct comparison to the predictions of the Woltjer-Taylor force-free model and Turner's generalization of magnetic relaxation in the presence of a non-zero Hall term and fluid vorticity.
Kim, Sang-Il; Seo, Min-Su; Park, Seung-Young; Kim, Dong-Jun; Park, Byong-Guk
2015-05-07
The dependence of the measured DC voltage on the non-magnetic material (NM) in NM/CoFeB and CoFeB/NM bilayers is studied under ferromagnetic resonance conditions in a TE{sub 011} resonant cavity. The directional change of the inverse spin Hall effect (ISHE) voltage V{sub ISHE} for the stacking order of the bilayer can separate the pure V{sub ISHE} and the anomalous Hall effect (AHE) voltage V{sub AHE} utilizing the method of addition and subtraction. The Ta and Ti NMs show a broad deviation of the spin Hall angle θ{sub ISH}, which originates from the AHE in accordance with the high resistivity of NMs. However, the Pt and Pd NMs show that the kinds of NMs with low resistivity are consistent with the previously reported θ{sub ISH} values. Therefore, the characteristics that NM should simultaneously satisfy to obtain a reasonable V{sub ISHE} value in bilayer systems are large θ{sub ISH} and low resistivity.
Hall transport of divalent metal ion modified DNA lattices
NASA Astrophysics Data System (ADS)
Dugasani, Sreekantha Reddy; Lee, Keun Woo; Kim, Si Joon; Yoo, Sanghyun; Gnapareddy, Bramaramba; Jung, Joohye; Jung, Tae Soo; Bashar, Saima; Kim, Hyun Jae; Park, Sung Ha
2015-06-01
We investigate the Hall transport characteristics of double-crossover divalent metal ion (Cu2+, Ni2+, Zn2+, and Co2+)-modified DNA (M-DNA) lattices grown on silica via substrate-assisted growth. The electronic characteristics of the M-DNA lattices are investigated by varying the concentration of the metal ions and then conducting Hall measurements, including resistivity, Hall mobility, carrier concentration, and magneto resistance. The tendency of the resistivity and Hall mobility was to initially decrease as the ion concentration increased, until reaching the saturation concentration (Cs) of each metal ion, and then to increase as the ion concentration increased further. On the other hand, the carrier concentration revealed the opposite tendency as the resistivity and Hall mobility. The specific binding (≤Cs) and the nonspecific aggregates (>Cs) of the ions into the DNA lattices were significantly affected by the Hall characteristics. The numerical ranges of the Hall parameters revealed that the M-DNA lattices with metal ions had semiconductor-like characteristics. Consequently, the distinct characteristics of the electrical transport through M-DNA lattices will provide useful information on the practical use of such structures in physical devices and chemical sensors.
Hall transport of divalent metal ion modified DNA lattices
Dugasani, Sreekantha Reddy; Lee, Keun Woo; Yoo, Sanghyun; Gnapareddy, Bramaramba; Bashar, Saima; Park, Sung Ha; Kim, Si Joon; Jung, Joohye; Jung, Tae Soo; Kim, Hyun Jae
2015-06-29
We investigate the Hall transport characteristics of double-crossover divalent metal ion (Cu{sup 2+}, Ni{sup 2+}, Zn{sup 2+}, and Co{sup 2+})-modified DNA (M-DNA) lattices grown on silica via substrate-assisted growth. The electronic characteristics of the M-DNA lattices are investigated by varying the concentration of the metal ions and then conducting Hall measurements, including resistivity, Hall mobility, carrier concentration, and magneto resistance. The tendency of the resistivity and Hall mobility was to initially decrease as the ion concentration increased, until reaching the saturation concentration (C{sub s}) of each metal ion, and then to increase as the ion concentration increased further. On the other hand, the carrier concentration revealed the opposite tendency as the resistivity and Hall mobility. The specific binding (≤C{sub s}) and the nonspecific aggregates (>C{sub s}) of the ions into the DNA lattices were significantly affected by the Hall characteristics. The numerical ranges of the Hall parameters revealed that the M-DNA lattices with metal ions had semiconductor-like characteristics. Consequently, the distinct characteristics of the electrical transport through M-DNA lattices will provide useful information on the practical use of such structures in physical devices and chemical sensors.
Piezo-Hall coefficients of n-type silicon
Haelg, B.
1988-07-01
The effect of uniaxial mechanical stress on the Hall coefficient of n-type silicon has been measured for various crystallographic orientations, and piezo-Hall coefficients P/sub 12/ and P/sub 11/-P/sub 44/ have been derived for electron concentrations n between 10/sup 14/ and 10/sup 16/ cm/sup -3/ and temperatures ranging from -80 to +100 /sup 0/C. In this range the piezo-Hall effect is found to be as important as the piezoresistance effect which is understood in terms of the many-valley band structure of silicon with anisotropic energy minima. For Hall plates in the (100) and the (110) plane of silicon the resulting longitudinal and transverse piezo-Hall coefficients at room temperature are plotted as a function of their orientation in the plane. It turns out that the piezo-Hall as well as the piezoresistance effects are minimized for a Hall plate in the (110) plane with the current flow roughly parallel to <11-bar1>.
Micro-Hall position sensing of magnetic nanowires.
Mihajlovic, G.; Hoffmann, A.; von Molnar, S.; Materials Science Division; Florida State Univ.
2009-01-01
The Hall voltage output of a micro-Hall magnetic sensor depends on the relative position of a magnetic nanowire with respect to its sensing area. Following this idea, we performed analytical calculations which show that, under certain conditions, these devices can track the position of a magnetic nanowire with subnanometer resolution. Our results suggest that micro-Hall sensors can be utilized to provide a direct electronic readout of the position of magnetic nanowires in their applications as biomolecular manipulators or dynamic components in micro- and nanoscale devices.
Modelling of micro-Hall sensors for magnetization imaging
NASA Astrophysics Data System (ADS)
Manzin, A.; Nabaei, V.
2014-05-01
This paper presents a numerical model for the study of micro-Hall magnetometry applications, aiming at evaluating the sensitivity of semiconductor miniaturized devices to the stray field of permalloy nanostructures with ring and disk geometry. The procedure couples a micromagnetic code, for the calculation of the stray field generated by the nanomagnet, to a 2D classical transport model for the determination of the electric potential distribution inside the Hall plate. The model is applied to study the sensitivity of a micro-Hall device in the detection of magnetization switching processes characterized by vortex state, focusing on the influence of magnetic nanostructure position.
Micro-Hall position sensing of magnetic nanowires
NASA Astrophysics Data System (ADS)
Mihajlović, G.; Hoffmann, A.; von Molnár, S.
2009-10-01
The Hall voltage output of a micro-Hall magnetic sensor depends on the relative position of a magnetic nanowire with respect to its sensing area. Following this idea, we performed analytical calculations which show that, under certain conditions, these devices can track the position of a magnetic nanowire with subnanometer resolution. Our results suggest that micro-Hall sensors can be utilized to provide a direct electronic readout of the position of magnetic nanowires in their applications as biomolecular manipulators or dynamic components in micro- and nanoscale devices.
Fractional quantum Hall effect in a tilted magnetic field
NASA Astrophysics Data System (ADS)
Papić, Z.
2013-06-01
We discuss the orbital effect of a tilted magnetic field on the quantum Hall effect in parabolic quantum wells. Many-body states realized at the fractional (1)/(3) and (1)/(2) filling of the second electronic subband are studied using finite-size exact diagonalization. In both cases, we obtain the phase diagram consisting of a fractional quantum Hall fluid phase that persists for moderate tilts, and eventually undergoes a direct transition to the stripe phase. It is shown that tilting of the field probes the geometrical degree of freedom of fractional quantum Hall fluids, and can be partly related to the effect of band-mass anisotropy.
Parametric Investigations of Miniaturized Cylindrical and Annular Hall Thrusters
A. Smirnov; Y. Raitses; N.J. Fisch
2001-10-16
A cylindrical geometry Hall thruster may overcome certain physical and technological limitations in scaling down of Hall thrusters to miniature sizes. The absence of the inner wall and use of the cusp magnetic field can potentially reduce heating of the thruster parts and erosion of the channel. A 2.6 cm miniaturized Hall thruster of a flexible design was built and successfully operated in the power range of 50-300 W. Comparison of preliminary results obtained for cylindrical and annular thruster configurations is presented.
Hall Conductivity in the Cosmic Defect and Dislocation Spacetime
NASA Astrophysics Data System (ADS)
Ma, Kai; Wang, Jian-Hua; Yang, Huan-Xiong; Fan, Hua-Wei
2016-10-01
Influences of topological defect and dislocation on conductivity behavior of charge carries in external electromagnetic fields are studied. Particularly the quantum Hall effect is investigated in detail. It is found that the nontrivial deformations of spacetime due to topological defect and dislocation produce an electric current at the leading order of perturbation theory. This current then induces a deformation on the Hall conductivity. The corrections on the Hall conductivity depend on the external electric fields, the size of the sample and the momentum of the particle.
Regularity criterion for the 3D Hall-magneto-hydrodynamics
NASA Astrophysics Data System (ADS)
Dai, Mimi
2016-07-01
This paper studies the regularity problem for the 3D incompressible resistive viscous Hall-magneto-hydrodynamic (Hall-MHD) system. The Kolmogorov 41 phenomenological theory of turbulence [14] predicts that there exists a critical wavenumber above which the high frequency part is dominated by the dissipation term in the fluid equation. Inspired by this idea, we apply an approach of splitting the wavenumber combined with an estimate of the energy flux to obtain a new regularity criterion. The regularity condition presented here is weaker than conditions in the existing criteria (Prodi-Serrin type criteria) for the 3D Hall-MHD system.
Determination of intrinsic spin Hall angle in Pt
Wang, Yi; Deorani, Praveen; Qiu, Xuepeng; Kwon, Jae Hyun; Yang, Hyunsoo
2014-10-13
The spin Hall angle in Pt is evaluated in Pt/NiFe bilayers by spin torque ferromagnetic resonance measurements and is found to increase with increasing the NiFe thickness. To extract the intrinsic spin Hall angle in Pt by estimating the total spin current injected into NiFe from Pt, the NiFe thickness dependent measurements are performed and the spin diffusion in the NiFe layer is taken into account. The intrinsic spin Hall angle of Pt is determined to be 0.068 at room temperature and is found to be almost constant in the temperature range of 13–300 K.
Properties of the photonic Hall effect in cold atomic clouds.
Grémaud, Benoît; Delande, Dominique; Sigwarth, Olivier; Miniatura, Christian
2009-05-29
On the basis of exact numerical simulations and analytical calculations, we describe qualitatively and quantitatively the interference processes at the origin of the photonic Hall effect for resonant Rayleigh (point-dipole) scatterers in a magnetic field. For resonant incoming light, the induced giant magneto-optical effects result, even for magnetic field strength as low as a few mT, in relative Hall currents in the percent range. This suggests that the observation of the photonic Hall effect in cold atomic vapors is within experimental reach.
Effective Field Theory of Fractional Quantized Hall Nematics
Mulligan, Michael; Nayak, Chetan; Kachru, Shamit; /Stanford U., Phys. Dept. /SLAC
2012-06-06
We present a Landau-Ginzburg theory for a fractional quantized Hall nematic state and the transition to it from an isotropic fractional quantum Hall state. This justifies Lifshitz-Chern-Simons theory - which is shown to be its dual - on a more microscopic basis and enables us to compute a ground state wave function in the symmetry-broken phase. In such a state of matter, the Hall resistance remains quantized while the longitudinal DC resistivity due to thermally-excited quasiparticles is anisotropic. We interpret recent experiments at Landau level filling factor {nu} = 7/3 in terms of our theory.
Is the quantum Hall effect influenced by the gravitational field?
Hehl, Friedrich W; Obukhov, Yuri N; Rosenow, Bernd
2004-08-27
Most of the experiments on the quantum Hall effect (QHE) were made at approximately the same height above sea level. A future international comparison will determine whether the gravitational field g(x) influences the QHE. In the realm of (1+2)-dimensional phenomenological macroscopic electrodynamics, the Ohm-Hall law is metric independent ("topological"). This suggests that it does not couple to g(x). We corroborate this result by a microscopic calculation of the Hall conductance in the presence of a post-Newtonian gravitational field. PMID:15447125
Combinatorial measurements of Hall effect and resistivity in oxide films.
Clayhold, J A; Kerns, B M; Schroer, M D; Rench, D W; Logvenov, G; Bollinger, A T; Bozovic, I
2008-03-01
A system for the simultaneous measurement of the Hall effect in 31 different locations as well as the measurement of the resistivity in 30 different locations on a single oxide thin film grown with a composition gradient is described. Considerations for designing and operating a high-throughput system for characterizing highly conductive oxides with Hall coefficients as small as 10(-10) m3/C are discussed. Results from measurements on films grown using combinatorial molecular beam epitaxy show the usefulness of characterizing combinatorial libraries via both the resistivity and the Hall effect. PMID:18377026
Topological Hall effect and Berry phase in magnetic nanostructures.
Bruno, P; Dugaev, V K; Taillefumier, M
2004-08-27
We discuss the anomalous Hall effect in a two-dimensional electron gas subject to a spatially varying magnetization. This topological Hall effect does not require any spin-orbit coupling and arises solely from Berry phase acquired by an electron moving in a smoothly varying magnetization. We propose an experiment with a structure containing 2D electrons or holes of diluted magnetic semiconductor subject to the stray field of a lattice of magnetic nanocylinders. The striking behavior predicted for such a system (of which all relevant parameters are well known) allows one to observe unambiguously the topological Hall effect and to distinguish it from other mechanisms. PMID:15447127
Kelvin-Helmholtz versus Hall magnetoshear instability in astrophysical flows.
Gómez, Daniel O; Bejarano, Cecilia; Mininni, Pablo D
2014-05-01
We study the stability of shear flows in a fully ionized plasma. Kelvin-Helmholtz is a well-known macroscopic and ideal shear-driven instability. In sufficiently low-density plasmas, also the microscopic Hall magnetoshear instability can take place. We performed three-dimensional simulations of the Hall-magnetohydrodynamic equations where these two instabilities are present, and carried out a comparative study. We find that when the shear flow is so intense that its vorticity surpasses the ion-cyclotron frequency of the plasma, the Hall magnetoshear instability is not only non-negligible, but it actually displays growth rates larger than those of the Kelvin-Helmholtz instability.
Magnet/Hall-Effect Random-Access Memory
NASA Technical Reports Server (NTRS)
Wu, Jiin-Chuan; Stadler, Henry L.; Katti, Romney R.
1991-01-01
In proposed magnet/Hall-effect random-access memory (MHRAM), bits of data stored magnetically in Perm-alloy (or equivalent)-film memory elements and read out by using Hall-effect sensors to detect magnetization. Value of each bit represented by polarity of magnetization. Retains data for indefinite time or until data rewritten. Speed of Hall-effect sensors in MHRAM results in readout times of about 100 nanoseconds. Other characteristics include high immunity to ionizing radiation and storage densities of order 10(Sup6)bits/cm(Sup 2) or more.
Spin Hall Effects Due to Phonon Skew Scattering
NASA Astrophysics Data System (ADS)
Gorini, Cosimo; Eckern, Ulrich; Raimondi, Roberto
2015-08-01
A diversity of spin Hall effects in metallic systems is known to rely on Mott skew scattering. In this work its high-temperature counterpart, phonon skew scattering, which is expected to be of foremost experimental relevance, is investigated. In particular, the phonon skew scattering spin Hall conductivity is found to be practically T independent for temperatures above the Debye temperature TD. As a consequence, in Rashba-like systems a high-T linear behavior of the spin Hall angle demonstrates the dominance of extrinsic spin-orbit scattering only if the intrinsic spin splitting is smaller than the temperature.
Hall conductance and topological invariant for open systems.
Shen, H Z; Wang, W; Yi, X X
2014-09-24
The Hall conductivity given by the Kubo formula is a linear response of quantum transverse transport to a weak electric field. It has been intensively studied for quantum systems without decoherence, but it is barely explored for systems subject to decoherence. In this paper, we develop a formulism to deal with this issue for topological insulators. The Hall conductance of a topological insulator coupled to an environment is derived, the derivation is based on a linear response theory developed for open systems in this paper. As an application, the Hall conductance of a two-band topological insulator and a two-dimensional lattice is presented and discussed.
Handbook of Agricultural Geophysics
Technology Transfer Automated Retrieval System (TEKTRAN)
Geophysical methods continue to show great promise for use in agriculture. The term “agricultural geophysics” denotes a subdiscipline of geophysics that is focused only on agricultural applications. The Handbook of Agricultural Geophysics was compiled to include a comprehensive overview of the geoph...
From University Heights to Cooperstown: Halls of Fame and American Memory
ERIC Educational Resources Information Center
Friss, Evan J.
2005-01-01
This article examines the development and function of American halls of fame as cultural memory institutions. By comparing the Hall of Fame for Great Americans with the National Baseball Hall of Fame, the author posits that halls of fame illuminate the ways in which cultural memory institutions can, through an archival process, preserve, instill,…
65. INTERIOR, FIRST FLOOR, WING 1100 EAST, AUDITORIUM (CONFERENCE HALL), ...
65. INTERIOR, FIRST FLOOR, WING 1100 EAST, AUDITORIUM (CONFERENCE HALL), DETAIL OF CEILING DECORATION - U.S. Department of the Interior, Eighteenth & C Streets Northwest, Washington, District of Columbia, DC
Basement hall under the northeast part of the building. Live ...
Basement hall under the northeast part of the building. Live animal cages and dissection rooms are to the right. Note concrete footings. - San Bernardino Valley College, Life Science Building, 701 South Mount Vernon Avenue, San Bernardino, San Bernardino County, CA
50. THIRD FLOOR, HALL, LOOKING SOUTH. Note ceiling extends down ...
50. THIRD FLOOR, HALL, LOOKING SOUTH. Note ceiling extends down over window case and exterior frieze extends halfway down top light of sash - Robinson-Aiken House, 48 Elizabeth Street, Charleston, Charleston County, SC
1. View looking west, showing side hall facade, wing, porch, ...
1. View looking west, showing side hall facade, wing, porch, setting and garage - First Free Will Baptist Church, Parsonage, South side of Dover Road, corner of Blackhall Road, Epsom, Merrimack County, NH
56. INTERIOR, FIRST FLOOR, WING 1100 EAST, AUDITORIUM (CONFERENCE HALL), ...
56. INTERIOR, FIRST FLOOR, WING 1100 EAST, AUDITORIUM (CONFERENCE HALL), REAR AISLE, LEATHER STUDDED DOOR (4' x 5' negative; 8' x 10' print) - U.S. Department of the Interior, Eighteenth & C Streets Northwest, Washington, District of Columbia, DC
Batch-fabricated high-performance graphene Hall elements.
Xu, Huilong; Zhang, Zhiyong; Shi, Runbo; Liu, Honggang; Wang, Zhenxing; Wang, Sheng; Peng, Lian-Mao
2013-01-01
Hall elements are by far the most widely used magnetic sensor. In general, the higher the mobility and the thinner the active region of the semiconductor used, the better the Hall device. While most common magnetic field sensors are Si-based Hall sensors, devices made from III-V compounds tend to favor over that based on Si. However these devices are more expensive and difficult to manufacture than Si, and hard to be integrated with signal-processing circuits for extending function and enforcing performance. In this article we show that graphene is intrinsically an ideal material for Hall elements which may harness the remarkable properties of graphene, i.e. extremely high carrier mobility and atomically thin active body, to create ideal magnetic sensors with high sensitivity, excellent linearity and remarkable thermal stability.
261. JEHOVAH'S WITNESSES HALL AT 1718, NORTH FRONT AND EAST ...
261. JEHOVAH'S WITNESSES HALL AT 1718, NORTH FRONT AND EAST SIDE, TOWARD SOUTHWEST, RUSSELL JUNIOR HIGH SCHOOL (RUSSELL APARTMENTS) IN BACKGROUND - Russell Neighborhood, Bounded by Congress & Esquire Alley, Fifteenth & Twenty-first Streets, Louisville, Jefferson County, KY
262. JEHOVAH'S WITNESSES HALL AT 1718, NORTH FRONT AND WEST ...
262. JEHOVAH'S WITNESSES HALL AT 1718, NORTH FRONT AND WEST SIDE, TOWARD SOUTHEAST, 515 SOUTH EIGHTEENTH STREET, NORTH SIDE, IN BACKGROUND - Russell Neighborhood, Bounded by Congress & Esquire Alley, Fifteenth & Twenty-first Streets, Louisville, Jefferson County, KY
View of attic space over Renaissance Hall from the east. ...
View of attic space over Renaissance Hall from the east. Central circular walkway provides maintenance access to ceiling lights for the room below. - Masonic Temple, 1 North Broad Street, Philadelphia, Philadelphia County, PA
12. Photocopy of photograph (original in Memorial Hall, Deerfield, Massachusetts) ...
12. Photocopy of photograph (original in Memorial Hall, Deerfield, Massachusetts) VIEW SHOWING PHOTOGRAPHS MD-227-10 & MD-227-11 AND ORIGINAL DOOR PULL - Kennedy Farm, Chestnut Grove Road, Samples Manor, Washington County, MD
9. Interior of Building 1009, view of central hall, looking ...
9. Interior of Building 1009, view of central hall, looking southeast - Naval Air Station Chase Field, Building 1009, Essex Street, .68 mile South-southeast of intersection of Texas State Highway 202 & Independence Street, Beeville, Bee County, TX
Interior view, anteroom of the postmaster general's reception hall; shown ...
Interior view, anteroom of the postmaster general's reception hall; shown here are two of the six aluminum statues of postal delivery men - New Post Office Building, Twelfth Street and Pennsylvania Avenue, Washington, District of Columbia, DC
INTERIOR VIEW OF SECOND FLOOR HALL. SHOWING THE IRON RAILING ...
INTERIOR VIEW OF SECOND FLOOR HALL. SHOWING THE IRON RAILING AND DOUBLE FLUSH WOOD DOORS TO THE LINEN CLOSET. VIEW FACING NORTH. - Hickam Field, Officers' Housing Type C, 208 Second Street, Honolulu, Honolulu County, HI
Enigmatic 12/5 fractional quantum Hall effect
NASA Astrophysics Data System (ADS)
Pakrouski, Kiryl; Troyer, Matthias; Wu, Yang-Le; Das Sarma, Sankar; Peterson, Michael R.
2016-08-01
We numerically study the fractional quantum Hall effect at filling factors ν =12 /5 and 13/5 (the particle-hole conjugate of 12/5) in high-quality two-dimensional GaAs heterostructures via exact diagonalization including finite well width and Landau-level mixing. We find that Landau-level mixing suppresses the ν =13 /5 fractional quantum Hall effect relative to ν =12 /5 . By contrast, we find both ν =2 /5 and (its particle-hole conjugate) ν =3 /5 fractional quantum Hall effects in the lowest Landau level to be robust under Landau-level mixing and finite well-width corrections. Our results provide a possible explanation for the experimental absence of the 13/5 fractional quantum Hall state as caused by Landau-level mixing effects.
11. Interior view of former mess hall; showing closed doorway ...
11. Interior view of former mess hall; showing closed doorway to former food storage; near northwest corner of building on main floor; view to east. - Ellsworth Air Force Base, Mess & Administration Building, 1561 Ellsworth Street, Blackhawk, Meade County, SD
18. VIEW OF STAIRCASE LEADING TO SOCIAL HALL ON CABIN ...
18. VIEW OF STAIRCASE LEADING TO SOCIAL HALL ON CABIN (POOP) DECK, LOCATED IN CENTER OF FORWARD END OF DINING SALOON - Steam Schooner WAPAMA, Kaiser Shipyard No. 3 (Shoal Point), Richmond, Contra Costa County, CA
36. NORTH AND EAST SIDES OF MAIN STAIR HALL SHOWING ...
36. NORTH AND EAST SIDES OF MAIN STAIR HALL SHOWING STAIRWAY, NORTH SCULPTURE PANEL, AND CEILING VAULT; LOOKING NORTHEAST (Harms & Wieskamp) - Dairy Industry Building, Iowa State University campus, Ames, Story County, IA
Life sciences building, north rear, also showing north hall to ...
Life sciences building, north rear, also showing north hall to the right, and the library in the center distance. - San Bernardino Valley College, 701 South Mount Vernon Avenue, San Bernardino, San Bernardino County, CA
48. INTERIOR, FIRST FLOOR, ENTRANCE HALL, DETAIL OF BUST OF ...
48. INTERIOR, FIRST FLOOR, ENTRANCE HALL, DETAIL OF BUST OF SAMUEL CLEMENTS AND WALL STENCILING - Mark Twain House, 351 Farmington Avenue (corrected from original address of 531 Farmington Avenue), Hartford, Hartford County, CT
Residence Halls Unit Agreements: A Step Beyond Rules and Regulations.
ERIC Educational Resources Information Center
Scheuermann, Thomas A.; Grandner, Deborah Francis
1986-01-01
Discusses the philosophical basis of the Unit Agreement program, provides a description of the Unit Agreement process and how it was developed, and presents the results of a campuswide study of the program's effect on the residence hall environment. (ABB)
27. View east, foreground north facade of Forest Hall, background ...
27. View east, foreground north facade of Forest Hall, background north facade of Forest East Suites. - Lake Placid Club, Forest Wing, East side of Mirror Lake Drive, North of State Route 86 & Main, North Elba, Essex County, NY
Hall Viscosity I: Linear Response Theory for Viscosity
NASA Astrophysics Data System (ADS)
Bradlyn, Barry; Goldstein, Moshe; Read, Nicholas
2012-02-01
In two dimensional systems with broken time-reversal symmetry, there can exist a non-dissipative viscosity coefficient [1,2,3]. This Hall viscosity is similar in nature to the non-dissipative Hall conductivity. In order to investigate this phenomenon further, we develop a linear response formalism for viscosity. We derive a Kubo formula for the frequency dependent viscosity tensor in the long wavelength limit. We compute the viscosity tensor for the free electron gas, integer quantum Hall systems, and two-dimensional paired superfluids. In the zero frequency limit, we show how the known results [3,4] for the Hall viscosity are recovered.[4pt] [1] J. Avron, R. Seiler, and P. Zograf, Phys. Rev. Lett. 75, 697 (1995).[0pt] [2] P. Levay, J. Math. Phys. 36, 2792 (1995).[0pt] [3] N. Read, Phys. Rev. B 79, 045308 (2009).[0pt] [4] N. Read and E. Rezayi, Phys. Rev. B 84, 085316 (2011).
31. HALL INTERIOR SHOWING SINGLE FRENCH DOOR TO NORTH SIDE ...
31. HALL INTERIOR SHOWING SINGLE FRENCH DOOR TO NORTH SIDE SCREENED PORCH, AND TRAP-DOOR ACCESS TO ATTIC. VIEW TO NORTHEAST. - Big Creek Hydroelectric System, Powerhouse 8, Operator Cottage, Big Creek, Big Creek, Fresno County, CA
Interior view of entry hall in Communication Center (now Break ...
Interior view of entry hall in Communication Center (now Break Room and Storage Area), facing north - MacDill Air Force Base, Fire & Guard House, 2709 Florida Keys Avenue, Tampa, Hillsborough County, FL
INTERIOR; VIEW OF ENTRY HALL, LOOKING SOUTH. Naval Computer ...
INTERIOR; VIEW OF ENTRY HALL, LOOKING SOUTH. - Naval Computer & Telecommunications Area Master Station, Eastern Pacific, Radio Transmitter Facility Lualualei, Marine Barracks, Intersection of Tower Drive & Morse Street, Makaha, Honolulu County, HI
11. GENERAL VIEW OF MEN'S BATH HALL. Hot Springs ...
11. GENERAL VIEW OF MEN'S BATH HALL. - Hot Springs National Park, Bathhouse Row, Fordyce Bathhouse: Mechanical & Piping Systems, State Highway 7, 1 mile north of U.S. Highway 70, Hot Springs, Garland County, AR
Survey of the Fermilab D0 detector collision hall
Babatunde O'Sheg Oshinowo
2001-07-20
The Fermilab D0 detector was used for the discovery of the top quark during Run I in 1996. It had been upgraded to exploit the physics potential to be presented by the Main Injector and the Tevatron Collider during Run II. The upgrade of the D0 detector was fully commissioned on March 1, 2001, and thus marked the official start of the Run II experiment. The detector which weighs about 5500 tons, was assembled in the Assembly Hall. Prior to moving the detector into the Collision Hall, the existing survey monuments were densified in the Collision Hall with new monuments. This paper discusses the survey of the Collision Hall using a combination of the Laser Tracker, BETS, V-Stars, and other Optical systems to within the specified accuracy of {+-}0.5mm.
INTERIOR VIEW OF THE SECOND FLOOR HALL. SHOWING THE IRON ...
INTERIOR VIEW OF THE SECOND FLOOR HALL. SHOWING THE IRON RAILING. NOTE THE TONGUE-AND-GROOVE WOOD FLOORING AND SINGLE PANEL DOORS. VIEW FACING SOUTH. - Hickam Field, Officers' Housing Type C, 208 Second Street, Honolulu, Honolulu County, HI
INTERIOR VIEW OF THE HALL. NOTE THE TELEPHONE NICHE, TONGUEANDGROOVE ...
INTERIOR VIEW OF THE HALL. NOTE THE TELEPHONE NICHE, TONGUE-AND-GROOVE WOOD FLOORING, AND DOUBLE DOOR OF THE LINEN CLOSET. VIEW FACING SOUTHWEST. - Hickam Field, Officers' Housing Type F, 602 Beard Avenue, Honolulu, Honolulu County, HI
INTERIOR VIEW SHOWING ORIGINAL TONGUEANDGROOVE WOOD FLOOR IN THE HALL ...
INTERIOR VIEW SHOWING ORIGINAL TONGUE-AND-GROOVE WOOD FLOOR IN THE HALL CLOSET. NOTE THE TYPICAL FIVE-PANEL DOORS. VIEW FACING NORTH. - Hickam Field, NCO Housing Type 3, 213 Tenth Street, Honolulu, Honolulu County, HI
INTERIOR VIEW OF THE SECOND FLOOR STAIR HALL. NOTE THE ...
INTERIOR VIEW OF THE SECOND FLOOR STAIR HALL. NOTE THE TONGUE-AND-GROOVE WOOD FLOORING AND THE WINDOW ABOVE THE STAIR LANDING. VIEW FACING SOUTH. - Hickam Field, Officers' Housing Type D, 111 Beard Avenue, Honolulu, Honolulu County, HI
21. INTERIOR, DOUBLE STAIRWAY LEADING TO MODEL HALL, DETAIL OF ...
21. INTERIOR, DOUBLE STAIRWAY LEADING TO MODEL HALL, DETAIL OF ONE FLIGHT (5 x 7 negative; 8 x 10 print) - Patent Office Building, Bounded by Seventh, Ninth, F & G Streets, Northwest, Washington, District of Columbia, DC
16. INDEPENDENCE HALL LOOKING SOUTH ON CHESTNUT ST. (horizontal line) ...
16. INDEPENDENCE HALL LOOKING SOUTH ON CHESTNUT ST. (horizontal line) BETWEEN SIXTH (right) AND FIFTH (left) STS. - Independence National Historical Park, Walnut, Sixth, Chestnut & Second Streets, Philadelphia, Philadelphia County, PA
76. TURBINE HALL, UNIT 2 SHOWING BOTH TURBINE AND CONDENSER ...
76. TURBINE HALL, UNIT 2 SHOWING BOTH TURBINE AND CONDENSER (SEE ALSO, DRAWING No. 12 OF 13) - Delaware County Electric Company, Chester Station, Delaware River at South end of Ward Street, Chester, Delaware County, PA
40. VIEW OF TURBINE HALL LOOKING SOUTHWEST AT WESTINGHOUSEPARSONS TURBINE ...
40. VIEW OF TURBINE HALL LOOKING SOUTHWEST AT WESTINGHOUSE-PARSONS TURBINE NUMBER 2. THIS UNIT WAS INSTALLED IN 1925. - New York, New Haven & Hartford Railroad, Cos Cob Power Plant, Sound Shore Drive, Greenwich, Fairfield County, CT
8. 451 MADISON AVENUE, MAIN HALL, SOUTH WALL, MOSAIC TYMPANUM ...
8. 451 MADISON AVENUE, MAIN HALL, SOUTH WALL, MOSAIC TYMPANUM OF THREE FIGURES IN BOLD RELIEF ABOVE FIREPLACE - Villard Houses, 451-457 Madison Avenue & 24 East Fifty-first Street, New York County, NY
BLDG 2 INTERIOR SHOWING ARCHES IN HALL BY MAIN ENTRY ...
BLDG 2 INTERIOR SHOWING ARCHES IN HALL BY MAIN ENTRY - Naval Magazine Lualualei, Headquarters Branch, Police Station, Kolekole Road & Constitution Street intersection, north side of main quad, Pearl City, Honolulu County, HI
Fractional quantum Hall effect in the absence of Landau levels.
Sheng, D N; Gu, Zheng-Cheng; Sun, Kai; Sheng, L
2011-01-01
It is well known that the topological phenomena with fractional excitations, the fractional quantum Hall effect, will emerge when electrons move in Landau levels. Here we show the theoretical discovery of the fractional quantum Hall effect in the absence of Landau levels in an interacting fermion model. The non-interacting part of our Hamiltonian is the recently proposed topologically non-trivial flat-band model on a checkerboard lattice. In the presence of nearest-neighbouring repulsion, we find that at 1/3 filling, the Fermi-liquid state is unstable towards the fractional quantum Hall effect. At 1/5 filling, however, a next-nearest-neighbouring repulsion is needed for the occurrence of the 1/5 fractional quantum Hall effect when nearest-neighbouring repulsion is not too strong. We demonstrate the characteristic features of these novel states and determine the corresponding phase diagram.
Theory of the thermal Hall effect in quantum magnets.
Katsura, Hosho; Nagaosa, Naoto; Lee, Patrick A
2010-02-12
We present a theory of the thermal Hall effect in insulating quantum magnets, where the heat current is totally carried by charge-neutral objects such as magnons and spinons. Two distinct types of thermal Hall responses are identified. For ordered magnets, the intrinsic thermal Hall effect for magnons arises when certain conditions are satisfied for the lattice geometry and the underlying magnetic order. The other type is allowed in a spin liquid which is a novel quantum state since there is no order even at zero temperature. For this case, the deconfined spinons contribute to the thermal Hall response due to Lorentz force. These results offer a clear experimental method to prove the existence of the deconfined spinons via a thermal transport phenomenon.
Nonlinear excitation of long-wavelength modes in Hall plasmas
NASA Astrophysics Data System (ADS)
Lakhin, V. P.; Ilgisonis, V. I.; Smolyakov, A. I.; Sorokina, E. A.
2016-10-01
Hall plasmas with magnetized electrons and unmagnetized ions exhibit a wide range of small scale fluctuations in the lower-hybrid frequency range as well as low-frequency large scale modes. Modulational instability of lower-hybrid frequency modes is investigated in this work for typical conditions in Hall plasma devices such as magnetrons and Hall thrusters. In these conditions, the dispersion of the waves in the lower-hybrid frequency range propagating perpendicular to the external magnetic field is due to the gradients of the magnetic field and the plasma density. It is shown that such lower-hybrid modes are unstable with respect to the secondary instability of the large scale quasimode perturbations. It is suggested that the large scale slow coherent modes observed in a number of Hall plasma devices may be explained as a result of such secondary instabilities.
10. Photocopy of photograph (original in Memorial Hall, Deerfield, Massachusetts) ...
10. Photocopy of photograph (original in Memorial Hall, Deerfield, Massachusetts) VIEW OF MAIN ELEVATION, SHOOTING FROM ROAD THROUGH TREES - Kennedy Farm, Chestnut Grove Road, Samples Manor, Washington County, MD
Interior view of hall to bath 1 showing typical doors ...
Interior view of hall to bath 1 showing typical doors and attic scuttle, facing east. - Albrook Air Force Station, Field Officer's Quarters, West side of Dargue Avenue Circle, Balboa, Former Panama Canal Zone, CZ
Wellness: A Developmental Programming Model for Residence Halls.
ERIC Educational Resources Information Center
Warner, Mark J.
1985-01-01
Demonstrates how a Wellness model can be an effective vehicle for promoting developmental programs in residence halls. The Wellness model is examined in terms of marketing, student development theory, and balanced programming. (BL)
Hall Determination of Atomic Radii of Alkali Metals
ERIC Educational Resources Information Center
Houari, Ahmed
2008-01-01
I will propose here an alternative method for determining atomic radii of alkali metals based on the Hall measurements of their free electron densities and the knowledge of their crystal structure. (Contains 2 figures.)
Interior view, stairwell and entrance to the great hall (note ...
Interior view, stairwell and entrance to the great hall (note Boardman Roberts's painting, Great Codifers of Law) - United States Department of Justice, Constitution Avenue between Ninth & Tenth Streets, Northwest, Washington, District of Columbia, DC
9. Front door, central hall interior view, cross and open ...
9. Front door, central hall interior view, cross and open bible configuration, with transom and sidelights, facing south. - Landers-Cain House, 915 Pleasant Hill Road, Lawrenceville, Gwinnett County, GA
INTERIOR VIEW OF ENTRY HALL. SHOWING THE ORIGINAL ACIDSTAINED CONCRETE ...
INTERIOR VIEW OF ENTRY HALL. SHOWING THE ORIGINAL ACID-STAINED CONCRETE FLOOR WITH INCISED STAR PATTERN. VIEW FACING SOUTHEAST. - Hickam Field, Officers' Housing Type C, 208 Second Street, Honolulu, Honolulu County, HI
Interior of the second floor dance hall showing tall and ...
Interior of the second floor dance hall showing tall and narrow window openings with 10-foot scale near center, looking south. - Bower Building, 409-413 East Weber Avenue, Stockton, San Joaquin County, CA
18. West room, second floor. View looking southeast. Center hall ...
18. West room, second floor. View looking southeast. Center hall visible through doorway. - Fort Hill Farm, Mansion, West of Staunton (Roanoke) River between Turkey & Caesar's Runs, Clover, Halifax County, VA
Linear Magnetization Dependence of the Intrinsic Anomalous Hall Effect
Zeng, C.; Yao, Y.; Niu, Q.; Weitering, Harm H
2006-01-01
The anomalous Hall effect is investigated experimentally and theoretically for ferromagnetic thin films of Mn{sub 5}Ge{sub 3}. We have separated the intrinsic and extrinsic contributions to the experimental anomalous Hall effect and calculated the intrinsic anomalous Hall conductivity from the Berry curvature of the Bloch states using first-principles methods. The intrinsic anomalous Hall conductivity depends linearly on the magnetization, which can be understood from the long-wavelength fluctuations of the spin orientation at finite temperatures. The quantitative agreement between theory and experiment is remarkably good, not only near 0 K but also at finite temperatures, up to about -240 K (0.8T{sub c}).
Interior view of main entry hall showing stairs and original ...
Interior view of main entry hall showing stairs and original pipe handrails, facing north. - Albrook Air Force Station, Parachute & Armament Building, 200 feet north of Andrews Boulevard, Balboa, Former Panama Canal Zone, CZ
17. LOOKING EAST FROM DOORWAY OF NORTHWEST BEDROOM, ACROSS HALL ...
17. LOOKING EAST FROM DOORWAY OF NORTHWEST BEDROOM, ACROSS HALL INTO NORTHEAST BEDROOM. PORCH DOOR IS AT LEFT. - Butt Valley Dam, Gate Tender's House, Butt Valley Reservoir Road, Caribou, Plumas County, CA
66. INTERIOR, FIRST FLOOR, WING 1100 EAST, AUDITORIUM (CONFERENCE HALL), ...
66. INTERIOR, FIRST FLOOR, WING 1100 EAST, AUDITORIUM (CONFERENCE HALL), DETAIL OF BRONZE GRILL IN BLIND GALLERY - U.S. Department of the Interior, Eighteenth & C Streets Northwest, Washington, District of Columbia, DC
20. INTERIOR OF SOUTHERN ROOM. VIEW LOOKING NORTHWEST TOWARD HALL ...
20. INTERIOR OF SOUTHERN ROOM. VIEW LOOKING NORTHWEST TOWARD HALL CONNECTING WITH CENTRAL ROOM. - Chollas Heights Naval Radio Transmitting Facility, Transmitter Building, 6410 Zero Road, San Diego, San Diego County, CA
DETAIL OF ENTRY HALL AND STAIR ON SOUTH SIDE, VIEW ...
DETAIL OF ENTRY HALL AND STAIR ON SOUTH SIDE, VIEW FACING NORTH (with scale stick). - Naval Air Station Barbers Point, Telephone Exchange, Coral Sea Road north of Bismarck Sea Road, Ewa, Honolulu County, HI
9. INTERIOR, VIEW SHOWING MAIN STAIRWAY AND ENTRY HALL THROUGH ...
9. INTERIOR, VIEW SHOWING MAIN STAIRWAY AND ENTRY HALL THROUGH ENTRY INTO PARLOR. TAKEN FROM SOUTHWEST CORNER OF PARLOR, LOOKING NORTHWEST - Farquhar House, 1601 Sandy Spring Road (Route 108), Sandy Spring, Montgomery County, MD
Revealing topological superconductivity in extended quantum spin Hall Josephson junctions.
Lee, Shu-Ping; Michaeli, Karen; Alicea, Jason; Yacoby, Amir
2014-11-01
Quantum spin Hall-superconductor hybrids are promising sources of topological superconductivity and Majorana modes, particularly given recent progress on HgTe and InAs/GaSb. We propose a new method of revealing topological superconductivity in extended quantum spin Hall Josephson junctions supporting "fractional Josephson currents." Specifically, we show that as one threads magnetic flux between the superconductors, the critical current traces an interference pattern featuring sharp fingerprints of topological superconductivity-even when noise spoils parity conservation.
Josephson inplane and tunneling currents in bilayer quantum Hall system
Ezawa, Z. F.; Tsitsishvili, G.; Sawada, A.
2013-12-04
A Bose-Einstein condensation is formed by composite bosons in the quantum Hall state. A composite boson carries the fundamental charge (–e). We investigate Josephson tunneling of such charges in the bilayer quantum Hall system at the total filling ν = 1. We show the existence of the critical current for the tunneling current to be coherent and dissipationless in tunneling experiments with various geometries.
Nulling Hall-Effect Current-Measuring Circuit
NASA Technical Reports Server (NTRS)
Sullender, Craig C.; Vazquez, Juan M.; Berru, Robert I.
1993-01-01
Circuit measures electrical current via combination of Hall-effect-sensing and magnetic-field-nulling techniques. Known current generated by feedback circuit adjusted until it causes cancellation or near cancellation of magnetic field produced in toroidal ferrite core by current measured. Remaining magnetic field measured by Hall-effect sensor. Circuit puts out analog signal and digital signal proportional to current measured. Accuracy of measurement does not depend on linearity of sensing components.
Linear waves in a resistive plasma with Hall current
Almaguer, J.A. )
1992-10-01
Dispersion relations for the case of a magnetized plasma are determined taking into account the Hall current and a constant resistivity, {eta}, in Ohm's law. It is found that the Hall effect is relevant only for parallel (to the equilibrium magnetic field) wave numbers in the case of uniform plasmas, giving place to a dispersive behavior. In particular, the cases of {eta}{r arrow}0 and small (nonzero) resistivity are discussed.
Hall effect measurements on InAs nanowires
Bloemers, Ch.; Grap, T.; Lepsa, M. I.; Moers, J.; Gruetzmacher, D.; Lueth, H.; Trellenkamp, St.; Schaepers, Th.
2012-10-08
We have processed Hall contacts on InAs nanowires grown by molecular beam epitaxy using an electron beam lithography process with an extremely high alignment accuracy. The carrier concentrations determined from the Hall effect measurements on these nanowires are lower by a factor of about 4 in comparison with those measured by the common field-effect technique. The results are used to evaluate quantitatively the charging effect of the interface and surface states.
GaAs Hall devices produced by local ion implantation
NASA Astrophysics Data System (ADS)
Pettenpaul, E.; Huber, J.; Weidlich, H.; Flossmann, W.; von Borcke, U.
1981-08-01
GaAs Hall devices were produced by complete planar technology using two selective silicon ion implantation steps. The fundamental characteristics of these devices with respect to reproducible implantation dose and geometry of cross-shaped elements are obtained both by experiment and calculation. The prominent properties of the GaAs Hall elements presented are high sensitivity and linearity, small temperature dependence of sensitivity and resistance, and low residual voltage.
Thermal neutron flux measurements in the STAR experimental hall
NASA Astrophysics Data System (ADS)
Fisyak, Yuri; Tsai, Oleg; Videbæk, Flemming; Xu, Zhangbu
2014-08-01
We report measurements of thermal neutron fluxes at different locations in the STAR experimental hall during RHIC Run 13 with proton-proton collisions at √{s}=510 GeV. We compare these measurements to calculations based on PYTHIA as a minimum bias event generator, detailed GEANT3 simulation of the STAR detector and experimental hall, and with GCALOR as the neutron transport code. A fairly good agreement was found between simulation and measurements.
Hall-Effect Current Sensors For Integrated Circuits
NASA Technical Reports Server (NTRS)
Rippel, Wally E.
1989-01-01
Built-in devices measure direct or alternating currents. Hall-effect sensors placed near constriction in conductor strip. Differential configuration reduces effects of stray magnetic fields, nonlinearities, and changes in temperature. Preliminary design studies and experiments with macroscopic commercial Hall-effect sensors conducted to assess feasibility, limitations, and need for further research and development of this concept. Potential applications include programmable power supplies and protective circuitry.
New Pathways Towards Efficient Metallic Spin Hall Spintronics
NASA Astrophysics Data System (ADS)
Jungfleisch, Matthias Benjamin; Zhang, Wei; Jiang, Wanjun; Hoffmann, Axel
2015-11-01
Spin Hall effects (SHEs) interconvert spin- and charge currents due to spin-orbit interaction, which enables convenient electrical generation and detection of diffusive spin currents and even collective spin excitations in magnetic solids. Here, we review recent experimental efforts exploring efficient spin Hall detector materials as well as new approaches to drive collective magnetization dynamics and to manipulate spin textures by SHEs. These studies are also expected to impact practical spintronics applications beyond their significance in fundamental research.
Low-Cost, High-Performance Hall Thruster Support System
NASA Technical Reports Server (NTRS)
Hesterman, Bryce
2015-01-01
Colorado Power Electronics (CPE) has built an innovative modular PPU for Hall thrusters, including discharge, magnet, heater and keeper supplies, and an interface module. This high-performance PPU offers resonant circuit topologies, magnetics design, modularity, and a stable and sustained operation during severe Hall effect thruster current oscillations. Laboratory testing has demonstrated discharge module efficiency of 96 percent, which is considerably higher than current state of the art.
Quantum Hall effect in bilayer system with array of antidots
NASA Astrophysics Data System (ADS)
Pagnossin, I. R.; Gusev, G. M.; Sotomayor, N. M.; Seabra, A. C.; Quivy, A. A.; Lamas, T. E.; Portal, J. C.
2007-04-01
We have studied the Quantum Hall effect in a bilayer system modulated by gate-controlled antidot lattice potential. The Hall resistance shows plateaus which are quantized to anomalous multiplies of h/e2. We suggest that this complex behavior is due to the nature of the edge-states in double quantum well (DQW) structures coupled to an array of antidots: these plateaus may be originated from the coexistence of normal and counter-rotating edge-states in different layers.
High-performance LED luminaire for sports hall
NASA Astrophysics Data System (ADS)
Lee, Xuan-Hao; Yang, Jin-Tsung; Chien, Wei-Ting; Chang, Jung-Hsuan; Lo, Yi-Chien; Lin, Che-Chu; Sun, Ching-Cherng
2015-09-01
In this paper, we present a luminaire design with anti-glare and energy-saving effects for sports hall. Compared with traditional lamps using in a badminton court, the average illuminance on the ground of the proposed LED luminaire is enhanced about 300%. Besides, the uniformity is obviously enhanced and improved. The switch-on speed of lighting in sports hall is greatly reduced from 5-10 minutes to 1 second. The simulation analysis and the corresponding experiment results are demonstrated.
2. EXTERIOR OF RUSIN HALL, THE ONLY STRUCTURE TO PREDATED ...
2. EXTERIOR OF RUSIN HALL, THE ONLY STRUCTURE TO PRE-DATED THE WORLD WAR II EXPANSION THAT LED TO THE DEMOLITION OF THE FIRST WARD OF HOMESTEAD, AN AREA KNOWN AS BELOW THE TRACKS. THE BUILDING WAS ORIGINALLY BUILT AS A FRATERNAL HALL FOR RUTHENIAN IMMIGRANTS BY THE RUSSKY-NARODNY-DOM, INC. - U.S. Steel Homestead Works, Auxiliary Buildings & Shops, Along Monongahela River, Homestead, Allegheny County, PA
Exciton Transport in a Bilayer Quantum Hall Superfluid
NASA Astrophysics Data System (ADS)
Eisenstein, J. P.; Finck, A. D. K.; Nandi, D.; Pfeiffer, L. N.; West, K. W.
2013-08-01
Bilayer quantum Hall systems at vT = 1 support an excitonic ground state. In addition to the usual charged quasiparticles, this system possesses a condensate degree of freedom: exciton transport. Detection of this neutral transport mode is facilitated by the use of the Corbino multiply-connected geometry in which charge transport is suppressed. We here summarize our recent experiments on Corbino devices which directly demonstrate exciton transport across the bulk of the incompressible vT = 1 quantum Hall state.
Direct Drive Hall Thruster System Development
NASA Technical Reports Server (NTRS)
Hoskins, W. Andrew; Homiak, Daniel; Cassady, R. Joseph; Kerslake, Tom; Peterson, Todd; Ferguson, Dale; Snyder, Dave; Mikellides, Ioannis; Jongeward, Gary; Schneider, Todd
2003-01-01
The sta:us of development of a Direct Drive Ha!! Thruster System is presented. 13 the first part. a s:udy of the impacts to spacecraft systems and mass benefits of a direct-drive architecture is reviewed. The study initially examines four cases of SPT-100 and BPT-4000 Hall thrusters used for north-south station keeping on an EXPRESS-like geosynchronous spacecraft and for primary propulsion for a Deep Space- 1 based science spacecraft. The study is also extended the impact of direct drive on orbit raising for higher power geosynchronous spacecraft and on other deep space missions as a function of power and delta velocity. The major system considerations for accommodating a direct drive Hall thruster are discussed, including array regulation, system grounding, distribution of power to the spacecraft bus, and interactions between current-voltage characteristics for the arrays and thrusters. The mass benefit analysis shows that, for the initial cases, up to 42 kg of dry mass savings is attributable directly to changes in the propulsion hardware. When projected mass impacts of operating the arrays and the electric power system at 300V are included, up to 63 kg is saved for the four initial cases. Adoption of high voltage lithium ion battery technology is projected to further improve these savings. Orbit raising of higher powered geosynchronous spacecraft, is the mission for which direct drive provides the most benefit, allowing higher efficiency electric orbit raising to be accomplished in a limited period of time, as well as nearly eliminating significant power processing heat rejection mass. The total increase in useful payload to orbit ranges up to 278 kg for a 25 kW spacecraft, launched from an Atlas IIA. For deep space missions, direct drive is found to be most applicable to higher power missions with delta velocities up to several km/s , typical of several Discovery-class missions. In the second part, the status of development of direct drive propulsion power
1986 Agricultural Chartbook. Agriculture Handbook No. 663.
ERIC Educational Resources Information Center
Department of Agriculture, Washington, DC.
This book contains 310 charts, tables, and graphs containing statistical information about agriculture-related commodities and services, primarily in the United States, in 1986. The book is organized in seven sections that cover the following topics: (1) the farm (farm income, farm population, farm workers, food and fiber system, agriculture and…
Agricultural Aircraft for Site-Specific Agriculture
Technology Transfer Automated Retrieval System (TEKTRAN)
Agricultural aircraft provide a convenient platform to aid in precision agriculture, in which pesticide, fertilizer or other field inputs are applied only where they are needed. This saves on chemical and farm resources, and reduces environmental loading. Remote sensing is used to spot areas of the ...
Agricultural Chartbook 1988. Agriculture Handbook No. 673.
ERIC Educational Resources Information Center
Department of Agriculture, Washington, DC.
These charts present an overview of the current economic health of American agriculture. The charts move from the national and international arenas to farm economic health measures and crop and livestock trends. A small amount of descriptive narrative accompanies most of the charts. Charts depicting the economic picture of U.S. agriculture include…
Spin-valley quantum Hall phases in graphene
NASA Astrophysics Data System (ADS)
Tian, Hong-Yu
2015-12-01
We theoretically investigate possible quantum Hall phases and corresponding edge states in graphene by taking a strong magnetic field, Zeeman splitting M, and sublattice potential Δ into account but without spin-orbit interaction. It was found that for the undoped graphene either a quantum valley Hall phase or a quantum spin Hall phase emerges in the system, depending on relative magnitudes of M and Δ. When the Fermi energy deviates from the Dirac point, the quantum spin-valley Hall phase appears and its characteristic edge state is contributed only by one spin and one valley species. The metallic boundary states bridging different quantum Hall phases possess a half-integer quantized conductance, like e2/2h or 3e2/2h. The possibility of tuning different quantum Hall states with M and Δ suggests possible graphene-based spintronics and valleytronics applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 11447218, 11274059, 11404278, and 11447216).
Spin Hall and Spin Nernst effect from first principles
NASA Astrophysics Data System (ADS)
Mertig, Ingrid
2013-03-01
Spintronics without magnetic materials is an interesting alternative to the existing spintronics applications. The spin Hall effect creates spin currents in nonmagnetic materials and avoids the problem of spin injection. Future applications of the spin Hall effect require two properties of the materials, a large spin Hall angle and a long spin diffusion length. Ab intio calculations based on density functional theory are a powerful tool to design the desired materials and to get insight into the underlying microscopic processes. We investigated the spin Hall effect in dilute alloys, in particular the intrinsic effect based on the Berry curvature as well as side-jump and the skew-scattering contributions. The results demonstrate that a large extrinsic spin Hall effect is determined by the differences between host and impurity concerning the spin-orbit interaction. It can be caused by light p scatterers as C and N in Au. A comparable large effect is observed for heavy p scatterers as Bi in Cu. An alternative way is to deposit impurities in the adatom position. Furthermore, we predict a spin current perpendicular to a temperature gradient. The phenomenon is called spin Nernst effect. The predicted spin currents can be comparably large as in the case of the spin Hall effect.
Magnetometry of micro-magnets with electrostatically defined Hall bars
Lachance-Quirion, Dany; Camirand Lemyre, Julien; Bergeron, Laurent; Sarra-Bournet, Christian; Pioro-Ladrière, Michel
2015-11-30
Micro-magnets are key components for quantum information processing with individual spins, enabling arbitrary rotations and addressability. In this work, characterization of sub-micrometer sized CoFe ferromagnets is performed with Hall bars electrostatically defined in a two-dimensional electron gas. Due to the ballistic nature of electron transport in the cross junction of the Hall bar, anomalies such as the quenched Hall effect appear near zero external magnetic field, thus hindering the sensitivity of the magnetometer to small magnetic fields. However, it is shown that the sensitivity of the diffusive limit can be almost completely restored at low temperatures using a large current density in the Hall bar of about 10 A/m. Overcoming the size limitation of conventional etched Hall bars with electrostatic gating enables the measurement of magnetization curves of 440 nm wide micro-magnets with a signal-to-noise ratio above 10{sup 3}. Furthermore, the inhomogeneity of the stray magnetic field created by the micro-magnets is directly measured using the gate-voltage-dependent width of the sensitive area of the Hall bar.
Magnetometry of micro-magnets with electrostatically defined Hall bars
NASA Astrophysics Data System (ADS)
Lachance-Quirion, Dany; Camirand Lemyre, Julien; Bergeron, Laurent; Sarra-Bournet, Christian; Pioro-Ladrière, Michel
2015-11-01
Micro-magnets are key components for quantum information processing with individual spins, enabling arbitrary rotations and addressability. In this work, characterization of sub-micrometer sized CoFe ferromagnets is performed with Hall bars electrostatically defined in a two-dimensional electron gas. Due to the ballistic nature of electron transport in the cross junction of the Hall bar, anomalies such as the quenched Hall effect appear near zero external magnetic field, thus hindering the sensitivity of the magnetometer to small magnetic fields. However, it is shown that the sensitivity of the diffusive limit can be almost completely restored at low temperatures using a large current density in the Hall bar of about 10 A/m. Overcoming the size limitation of conventional etched Hall bars with electrostatic gating enables the measurement of magnetization curves of 440 nm wide micro-magnets with a signal-to-noise ratio above 103. Furthermore, the inhomogeneity of the stray magnetic field created by the micro-magnets is directly measured using the gate-voltage-dependent width of the sensitive area of the Hall bar.
Acoustics in Halls for Speech and Music
NASA Astrophysics Data System (ADS)
Gade, Anders C.
This chapter deals specifically with concepts, tools, and architectural variables of importance when designing auditoria for speech and music. The focus will be on cultivating the useful components of the sound in the room rather than on avoiding noise from outside or from installations, which is dealt with in Chap. 11. The chapter starts by presenting the subjective aspects of the room acoustic experience according to consensus at the time of writing. Then follows a description of their objective counterparts, the objective room acoustic parameters, among which the classical reverberation time measure is only one of many, but still of fundamental value. After explanations on how these parameters can be measured and predicted during the design phase, the remainder of the chapter deals with how the acoustic properties can be controlled by the architectural design of auditoria. This is done by presenting the influence of individual design elements as well as brief descriptions of halls designed for specific purposes, such as drama, opera, and symphonic concerts. Finally, some important aspects of loudspeaker installations in auditoria are briefly touched upon.
Planar Hall magnetoresistive aptasensor for thrombin detection.
Sinha, B; Ramulu, T S; Kim, K W; Venu, R; Lee, J J; Kim, C G
2014-09-15
The use of aptamer-based assays is an emerging and attractive approach in disease research and clinical diagnostics. A sensitive aptamer-based sandwich-type sensor is presented to detect human thrombin using a planar Hall magnetoresistive (PHR) sensor in cooperation with superparamagnetic labels. A PHR sensor has the great advantages of a high signal-to-noise ratio, a small offset voltage and linear response in the low-field region, allowing it to act as a high-resolution biosensor. In the system presented here, the sensor has an active area of 50 µm × 50 µm with a 10-nm gold layer deposited onto the sensor surface prior to the binding of thiolated DNA primary aptamer. A polydimethylsiloxane well of 600-µm radius and 1-mm height was prepared around the sensor surface to maintain the same specific area and volume for each sensor. The sensor response was traced in real time upon the addition of streptavidin-functionalized magnetic labels on the sensor. A linear response to the thrombin concentration in the range of 86 pM-8.6 µM and a lower detection limit down to 86 pM was achieved by the proposed present method with a sample volume consumption of 2 µl. The proposed aptasensor has a strong potential for application in clinical diagnosis.
Gauge Physics of Spin Hall Effect.
Tan, Seng Ghee; Jalil, Mansoor B A; Ho, Cong Son; Siu, Zhuobin; Murakami, Shuichi
2015-01-01
Spin Hall effect (SHE) has been discussed in the context of Kubo formulation, geometric physics, spin orbit force, and numerous semi-classical treatments. It can be confusing if the different pictures have partial or overlapping claims of contribution to the SHE. In this article, we present a gauge-theoretic, time-momentum elucidation, which provides a general SHE equation of motion, that unifies under one theoretical framework, all contributions of SHE conductivity due to the kinetic, the spin orbit force (Yang-Mills), and the geometric (Murakami-Fujita) effects. Our work puts right an ambiguity surrounding previously partial treatments involving the Kubo, semiclassical, Berry curvatures, or the spin orbit force. Our full treatment shows the Rashba 2DEG SHE conductivity to be [formula in text] instead of [formula in text], and Rashba heavy hole [formula in text] instead of [formula in text]. This renewed treatment suggests a need to re-derive and re-calculate previously studied SHE conductivity. PMID:26689260
Bilayer fractional quantum Hall states with dipoles
NASA Astrophysics Data System (ADS)
Yao, N. Y.; Bennett, S. D.; Laumann, C. R.; Lev, B. L.; Gorshkov, A. V.
2015-09-01
Using the example of dysprosium atoms in an optical lattice, we show how dipolar interactions between magnetic dipoles can be used to obtain fractional quantum Hall states. In our approach, dysprosium atoms are trapped one atom per site in a deep optical lattice with negligible tunneling. Microwave and spatially dependent optical dressing fields are used to define an effective spin-1/2 or spin-1 degree of freedom in each atom. Thinking of spin-1/2 particles as hard-core bosons, dipole-dipole interactions give rise to boson hopping, topological flat bands with Chern number 1, and the ν =1/2 Laughlin state. Thinking of spin-1 particles as two-component hard-core bosons, dipole-dipole interactions again give rise to boson hopping, topological flat bands with Chern number 2, and the bilayer Halperin (2,2,1) state. By adjusting the optical fields, we find a phase diagram, in which the (2,2,1) state competes with superfluidity. Generalizations to solid-state magnetic dipoles are discussed.
Hall Effect and Magneto Optical MFL Sensing
NASA Astrophysics Data System (ADS)
Jallouli, Wissem
The need for a reliable sensing tool has stimulated countless researchers to develop techniques trying to extract maximum information. In the field of nondestructive testing (NDT), various sensors have been established to fulfill that function. Examples include the ultrasonic, eddy current, and magnetic flux leakage (MFL) based techniques. Because they are extremely reliable, MFL based techniques represent one of the best inspection technologies. These technologies have numerous applications in diverse domains, including petroleum pipeline and tank inspections, airplane inspections, and production quality control. In this work, we will present two technologies based on MFL technique. The first is the Hall Effect sensor. This device has been extensively developed during the last century, especially after the use of integrated circuit technology. Its reliable results even under extreme conditions made it an extremely useful tool. The second technology is Magneto Optical Imaging. This technique rose very recently, and scientists hold high expectations about its performance once proper techniques are developed. The study of these two sensing devices gives a better understanding of the MFL technique by allowing us to investigate the potential of each technology, experience each in studied conditions to derive its characteristics, and discuss its performance.
Evaluation of Low Power Hall Thruster Propulsion
NASA Technical Reports Server (NTRS)
Manzella, David; Oleson, Steve; Sankovic, John; Haag, Tom; Semenkin, Alexander; Kim, Vladimir
1996-01-01
Hall thruster systems based on the SPT-50 and the TAL D-38 were evaluated and mission studies were performed. The 0.3 kilowatt SPT-50 operated with a specific impulse of 1160 seconds and an efficiency of 0.32. The 0.8 kilowatt D-38 provided a specific impulse above 1700 seconds at an efficiency of 0.5. The D-38 system was shown to offer a 56 kilogram propulsion system mass savings over a 101 kilogram hydrazine monopropellant system designed to perform North-South station keeping maneuvers on board a 430 kilogram geostationary satellite. The SPIT-50 system offered a greater than 50% propulsion system mass reduction in comparison to the chemical system on board a 200 kilogram low Earth orbit spacecraft performing two orbit raises and drag makeup over two years. The performance characteristics of the SPF-50 were experimentally evaluated at a number of operating conditions. The ion current density distribution of this engine was measured. The performance and system mass benefits of advanced systems based on both engines were considered.
The Theory of the Quantum Hall Effect
NASA Astrophysics Data System (ADS)
Shrivastava, Keshav N.
2008-05-01
Laughlin's theory of fractional charges is worked out in detail for small charges from 1/3 till 1/101. There is a small deviation between computed values and those obtained from the closed form expression. The ground state energy crosses that of the charge-density waves. We develop a theory of fractional charges by using the quantum mechanics of angular momentum. We find that fractional charges can be expressed in terms of spin and the values of charges 0, 1, 1/3, 2/3, 2/5, 3/5, …, are produced. The angular momenta eigen values when subjected to flux quantization, yield plateaus of energies which are independent of the magnetic field. In this way we are able to predict that charges of ±2e, ±6e, ±10e, ±14e, …, are produced. The higher order term in the flux quantization also produces quasiparticles of charges of ±4e. These calculated values of the charges are the same as those found in the experimental data of quantum Hall effect in graphene, which is a mono-atomic layer of carbon. Since the charge of the quasiparticles appears in the resistivity and there is a strong need of the electron spin to predict these charges, spin-charge coupling occurs in a natural way.
Geometric defects in quantum Hall states
NASA Astrophysics Data System (ADS)
Gromov, Andrey
2016-08-01
We describe a geometric (or gravitational) analog of the Laughlin quasiholes in fractional quantum Hall states. Analogously to the quasiholes, these defects can be constructed by an insertion of an appropriate vertex operator into the conformal block representation of a trial wave function; however, unlike the quasiholes these defects are extrinsic and do not correspond to true excitations of the quantum fluid. We construct a wave function in the presence of such defects and explain how to assign an electric charge and a spin to each defect and calculate the adiabatic, non-Abelian statistics of the defects. The defects turn out to be equivalent to the genons in that their adiabatic exchange statistics can be described in terms of representations of the mapping class group of an appropriate higher genus Riemann surface. We present a general construction that, in principle, makes it possible to calculate the statistics of Zn genons for any "parent" topological phase. We illustrate the construction on the example of the Laughlin state and perform an explicit calculation of the braiding matrices. In addition to non-Abelian statistics, geometric defects possess a universal Abelian overall phase, determined by the gravitational anomaly.
The integer quantum hall effect revisited
Michalakis, Spyridon; Hastings, Matthew
2009-01-01
For T - L x L a finite subset of Z{sup 2}, let H{sub o} denote a Hamiltonian on T with periodic boundary conditions and finite range, finite strength intetactions and a unique ground state with a nonvanishing spectral gap. For S {element_of} T, let q{sub s} denote the charge at site s and assume that the total charge Q = {Sigma}{sub s {element_of} T} q{sub s} is conserved. Using the local charge operators q{sub s}, we introduce a boundary magnetic flux in the horizontal and vertical direction and allow the ground state to evolve quasiadiabatically around a square of size one magnetic flux, in flux space. At the end of the evolution we obtain a trivial Berry phase, which we compare, via a method reminiscent of Stokes Theorem. to the Berry phase obtained from an evolution around an exponentially small loop near the origin. As a result, we show, without any averaging assumption, that the Hall conductance is quantized in integer multiples of e{sup 2}/h up to exponentially small corrections of order e{sup -L/{zeta}}, where {zeta}, is a correlation length that depends only on the gap and the range and strength of the interactions.
Quantum Spin Hall phase in multilayer graphene
NASA Astrophysics Data System (ADS)
Garcia, Noel; Lado, Jose Luis; Fernandez-Rossier, Joaquin; Theory of Nanostructures Team
2015-03-01
We address the question of whether multilayer graphene systems are Quantum Spin Hall (QSH) insulators. Since interlayer coupling coples pz orbitals to s orbitals of different layers and Spin-Orbit (SO) couples pz orbitals with px and py of opposite spins, new spins mixing channels appear in the multilayer scenario that were not present in the monolayer. These new spin-mixing channels cast a doubt on the validity of the spin-conserving Kane-Mele model for multilayers and motivates our choice of a four orbital tight-binding model in the Slater-Koster approximation with intrinsic Spin-Orbit interaction. To completely determine if the QSH phase is present we calculate for different number of layers both the Z2 invariant for different stackings (only for inversion symmetric systems), and the density of states at the edge of semi-infinite graphene ribbon with armchair termination. We find that systems with even number of layers are normal insulators while systems with odd number of layers are QSH insulators, regardless of the stacking. We acknowledge financial support by Marie-Curie-ITN 607904-SPINOGRAPH.
Quantum Spin Hall Effect in Ultrasonic Metamaterials
NASA Astrophysics Data System (ADS)
Mousavi, S. Hossein; Khanikaev, Alexander B.; Wang, Zheng
2015-03-01
The discovery of topological order without breaking time-reversal symmetry, such as that in Quantum Spin Hall (QSH) effect and Topological Insulators, is one of the most groundbreaking advancements of recent years in condensed matters physics. The approach to topological order without breaking time-reversal symmetry is particularly important in elastics because no natural elastic materials show linear nonreciprocal response. Here we illustrate the first elastic-wave system emulating QSH effect and demonstrate existence of topologically protected elastic edge states. The system represents an elastic metamaterial-based phononic crystal. In this crystal, we achieved degenerate linear dispersion for two sets of modes, classified by one of the system's symmetries. Then, by relaxing and removing that symmetry by deliberately engineering a gauge field emulating a strong spin-orbit coupling of QSH, we observe opening a complete topological bandgap. Finally, the hallmark of the topological order, namely the presence of one-way chiral edge waves insensitive to nonmagnetic defects and disorders, is demonstrated in such elastic metacrystals. We illustrate the unique property of these elastic edge waves to flow around sharp corners without back-reflection or localization.
Federal Register 2010, 2011, 2012, 2013, 2014
2010-02-19
...: Mr. Gary E. Hall and Ms. Rita C. Hall, P.O. Box 133, Olney, MT 59927, (406) 881-2345. i. FERC Contact... having a storage capacity of 0.14 acre-feet of water; (3) a 4-inch-diameter, 111-foot-long PVC penstock...-river. o. A copy of the application is available for review at The Commission in the Public...
ERIC Educational Resources Information Center
Breese, William Ellis, II
2012-01-01
The purpose of this study is to examine if residence hall roommate placement of traditional freshman students at MSOE affects their satisfaction with the residence halls. The idea behind this study is that if residence hall roommate placement is done purposefully, with the participation of incoming freshmen through appropriate placement…
Yamaguchi, Akinobu; Saito, Hiromasa; Shimizu, Masayoshi; Miyajima, Hideki; Matsumoto, Satoru; Nakamura, Yoshiharu; Hirohata, Atsufumi
2008-08-01
We demonstrate successful operation of a scanning Hall probe microscope with a few micron-size resolution by using a silicon metal-oxide semiconductor field-effect transistor (Si-MOSFET) Hall bar, which is designed to improve not only the mechanical strength but also the temperature stability. The Si-MOSFET micro-Hall probe is cheaper than the current micro-Hall probes and is found to be as sensitive as a micro-Hall probe with GaAs/AlGaAs heterostructure or an epitaxial InSb two-dimensional electron gas. This was used to magnetically image the surface of a Sm(2)Co(17) permanent magnet during the magnetization reversal process as a function of an external magnetic field below 1.5 T. This revealed firm evidence of the presence of the inverse magnetic seed as theoretically predicted earlier. Magnetically pinned centers, with a typical size 80 mum, are observed to persist even under a high magnetic field, clearly indicating the robustness of the Si Hall probe against the field application as well as the repetition of the measurement. PMID:19044353
Yamaguchi, Akinobu; Saito, Hiromasa; Shimizu, Masayoshi; Miyajima, Hideki; Matsumoto, Satoru; Nakamura, Yoshiharu; Hirohata, Atsufumi
2008-08-01
We demonstrate successful operation of a scanning Hall probe microscope with a few micron-size resolution by using a silicon metal-oxide semiconductor field-effect transistor (Si-MOSFET) Hall bar, which is designed to improve not only the mechanical strength but also the temperature stability. The Si-MOSFET micro-Hall probe is cheaper than the current micro-Hall probes and is found to be as sensitive as a micro-Hall probe with GaAs/AlGaAs heterostructure or an epitaxial InSb two-dimensional electron gas. This was used to magnetically image the surface of a Sm(2)Co(17) permanent magnet during the magnetization reversal process as a function of an external magnetic field below 1.5 T. This revealed firm evidence of the presence of the inverse magnetic seed as theoretically predicted earlier. Magnetically pinned centers, with a typical size 80 mum, are observed to persist even under a high magnetic field, clearly indicating the robustness of the Si Hall probe against the field application as well as the repetition of the measurement.
Agricultural Libraries and Information.
ERIC Educational Resources Information Center
Russell, Keith W., Ed.; Pisa, Maria G., Ed.
1990-01-01
Eleven articles address issues relating to agricultural libraries and information, including background on agricultural libraries and information, trend management, document delivery, reference services, user needs and library services, collection development, technologies for international information management, information sources,…
Theme: Delivering Agricultural Literacy.
ERIC Educational Resources Information Center
Reed, Warren D.; And Others
1990-01-01
Eight articles in this theme issue deal with the nationwide implementation of agricultural literacy programs--discovering how to do it. Discussed are experiences in planning and conducting agricultural literacy programs at state and local levels. (JOW)
Traditional Agriculture and Permaculture.
ERIC Educational Resources Information Center
Pierce, Dick
1997-01-01
Discusses benefits of combining traditional agricultural techniques with the concepts of "permaculture," a framework for revitalizing traditions, culture, and spirituality. Describes school, college, and community projects that have assisted American Indian communities in revitalizing sustainable agricultural practices that incorporate cultural…
Vocational Agriculture in Ponape
ERIC Educational Resources Information Center
Dayrit, Ruben S.
1975-01-01
The general objectives of agriculture education in both the elementary and secondary schools in Ponape District are to develop interest in agriculture among students and to provide practical and technical skills in growing crops and raising domestic animals. (Author)
ERIC Educational Resources Information Center
Corbellini, Margaret
1991-01-01
John Bourne High School in Queens, New York, offers an agricultural program enrolling more than 400 students. The curriculum includes agricultural career exploration, plant and animal science, summer land laboratories, and a special education component. (SK)
ERIC Educational Resources Information Center
Crosson, Pierre R.; Rosenberg, Norman J.
1989-01-01
Discusses the change of agricultural methods with human population growth. Describes the trends of world food production, changes in farmland, use of fertilizer, and 13 agricultural research institutions. Lists 5 references for further reading. (YP)
Biotechnology and Agriculture.
ERIC Educational Resources Information Center
Kenney, Martin
Even at this early date in the application of biotechnology to agriculture, it is clear that agriculture may provide the largest market for new or less expensive biotechnologically manufactured products. The chemical and pharmaceutical industries that hold important positions in agricultural inputs are consolidating their positions by purchasing…
Agriculture Business and Management.
ERIC Educational Resources Information Center
Seperich, George; And Others
This curriculum guide is intended for vocational agriculture teachers who deliver agricultural business and management programs at the secondary or postsecondary level. It is based on the Arizona validated occupational competencies and tasks for management and supervisory positions in agricultural business. The competency/skill and task list…
Agricultural Education: Value Adding.
ERIC Educational Resources Information Center
Riesenberg, Lou E.; And Others
1989-01-01
This issue develops the theme of "Agricultural Education--Value Adding." The concept value adding has been a staple in the world of agricultural business for describing adding value to a commodity that would profit the producer and the local community. Agricultural education should add value to individuals and society to justify agricultural…
Information for Agricultural Development.
ERIC Educational Resources Information Center
Kaungamno, E. E.
This paper describes the major international agricultural information services, sources, and systems; outlines the existing information situation in Tanzania as it relates to problems of agricultural development; and reviews the improvements in information provision resources required to support the process of agricultural development in Tanzania.…
Chapter 3: Cropland Agriculture
Technology Transfer Automated Retrieval System (TEKTRAN)
In 2013, cropland agriculture resulted in total emissions of approximately 209 MMT CO2 eq. of greenhouse gases (GHG). Cropland agriculture is responsible for almost half (46%) of all emissions from the agricultural sector. Nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) emissions from c...
ERIC Educational Resources Information Center
Netherlands Ministry of Agriculture and Fisheries, The Hauge.
Agricultural Education in the Netherlands is categorized as Scientific, Higher Secondary, Middle Secondary, and Lower Secondary. Scientific education is given at the agricultural university which has a 6- or 7-year curriculum. Higher secondary education is given at agricultural and horticultural colleges with a 3- to 4-year curriculum. Middle…
Agricultural Structures, Volume II.
ERIC Educational Resources Information Center
Linhardt, Richard E.; Burhoe, Steve
This guide to a curriculum unit in agricultural structures is designed to expand the curriculum materials available in vocational agriculture in Missouri. It and Agricultural Structures I (see note) provide reference materials to systematize the curriculum. The six units cover working with concrete (19 lessons, 2 laboratory exercises), drawing and…
Agriculture, Environmental Education Guide.
ERIC Educational Resources Information Center
Project I-C-E, Green Bay, WI.
This agriculture guide, for use at the secondary level, is one of a series of guides, K-12, which were developed by teachers to help introduce environmental education into the total curriculum. Environmental problems are present in every community where agriculture education is offered, and therefore many agriculture teachers have included some…
Mode Transitions in Hall Effect Thrusters
NASA Technical Reports Server (NTRS)
Sekerak, Michael J.; Longmier, Benjamin W.; Gallimore, Alec D.; Brown, Daniel L.; Hofer, Richard R.; Polk, James E.
2013-01-01
Mode transitions have been commonly observed in Hall Effect Thruster (HET) operation where a small change in a thruster operating parameter such as discharge voltage, magnetic field or mass flow rate causes the thruster discharge current mean value and oscillation amplitude to increase significantly. Mode transitions in a 6-kW-class HET called the H6 are induced by varying the magnetic field intensity while holding all other operating parameters constant and measurements are acquired with ion saturation probes and ultra-fast imaging. Global and local oscillation modes are identified. In the global mode, the entire discharge channel oscillates in unison and azimuthal perturbations (spokes) are either absent or negligible. Downstream azimuthally spaced probes show no signal delay between each other and are very well correlated to the discharge current signal. In the local mode, signals from the azimuthally spaced probes exhibit a clear delay indicating the passage of "spokes" and are not well correlated to the discharge current. These spokes are localized oscillations propagating in the ExB direction that are typically 10-20% of the mean value. In contrast, the oscillations in the global mode can be 100% of the mean value. The transition between global and local modes occurs at higher relative magnetic field strengths for higher mass flow rates or higher discharge voltages. The thrust is constant through mode transition but the thrust-to-power decreased by 25% due to increasing discharge current. The plume shows significant differences between modes with the global mode significantly brighter in the channel and the near-field plasma plume as well as exhibiting a luminous spike on thruster centerline. Mode transitions provide valuable insight to thruster operation and suggest improved methods for thruster performance characterization.
Azimuthal Spoke Propagation in Hall Effect Thrusters
NASA Technical Reports Server (NTRS)
Sekerak, Michael J.; Longmier, Benjamin W.; Gallimore, Alec D.; Brown, Daniel L.; Hofer, Richard R.; Polk, James E.
2013-01-01
Spokes are azimuthally propagating perturbations in the plasma discharge of Hall Effect Thrusters (HETs) that travel in the E x B direction and have been observed in many different systems. The propagation of azimuthal spokes are investigated in a 6 kW HET known as the H6 using ultra-fast imaging and azimuthally spaced probes. A spoke surface is a 2-D plot of azimuthal light intensity evolution over time calculated from 87,500 frames/s videos. The spoke velocity has been determined using three methods with similar results: manual fitting of diagonal lines on the spoke surface, linear cross-correlation between azimuthal locations and an approximated dispersion relation. The spoke velocity for three discharge voltages (300, 400 and 450 V) and three anode mass flow rates (14.7, 19.5 and 25.2 mg/s) yielded spoke velocities between 1500 and 2200 m/s across a range of normalized magnetic field settings. The spoke velocity was inversely dependent on magnetic field strength for low B-field settings and asymptoted at B-field higher values. The velocities and frequencies are compared to standard drifts and plasma waves such as E x B drift, electrostatic ion cyclotron, magnetosonic and various drift waves. The empirically approximated dispersion relation yielded a characteristic velocity that matched the ion acoustic speed for 5 eV electrons that exist in the near-anode and near-field plume regions of the discharge channel based on internal measurements. Thruster performance has been linked to operating mode where thrust-to-power is maximized when azimuthal spokes are present so investigating the underlying mechanism of spokes will benefit thruster operation.
Concert halls with strong lateral reflections enhance musical dynamics.
Pätynen, Jukka; Tervo, Sakari; Robinson, Philip W; Lokki, Tapio
2014-03-25
One of the most thrilling cultural experiences is to hear live symphony-orchestra music build up from a whispering passage to a monumental fortissimo. The impact of such a crescendo has been thought to depend only on the musicians' skill, but here we show that interactions between the concert-hall acoustics and listeners' hearing also play a major role in musical dynamics. These interactions contribute to the shoebox-type concert hall's established success, but little prior research has been devoted to dynamic expression in this three-part transmission chain as a complete system. More forceful orchestral playing disproportionately excites high frequency harmonics more than those near the note's fundamental. This effect results in not only more sound energy, but also a different tone color. The concert hall transmits this sound, and the room geometry defines from which directions acoustic reflections arrive at the listener. Binaural directional hearing emphasizes high frequencies more when sound arrives from the sides of the head rather than from the median plane. Simultaneously, these same frequencies are emphasized by higher orchestral-playing dynamics. When the room geometry provides reflections from these directions, the perceived dynamic range is enhanced. Current room-acoustic evaluation methods assume linear behavior and thus neglect this effect. The hypothesis presented here is that the auditory excitation by reflections is emphasized with an orchestra forte most in concert halls with strong lateral reflections. The enhanced dynamic range provides an explanation for the success of rectangularly shaped concert-hall geometry.
High temperature Hall measurement setup for thin film characterization
NASA Astrophysics Data System (ADS)
Adnane, L.; Gokirmak, A.; Silva, H.
2016-07-01
Hall measurement using the van der Pauw technique is a common characterization approach that does not require patterning of contacts. Measurements of the Hall voltage and electrical resistivity lead to the product of carrier mobility and carrier concentration (Hall coefficient) which can be decoupled through transport models. Based on the van der Paw method, we have developed an automated setup for Hall measurements from room temperature to ˜500 °C of semiconducting thin films of a wide resistivity range. The resistivity of the film and Hall coefficient is obtained from multiple current-voltage (I-V) measurements performed using a semiconductor parameter analyzer under applied constant "up," zero, and "down" magnetic field generated with two neodymium permanent magnets. The use of slopes obtained from multiple I-Vs for the three magnetic field conditions offer improved accuracy. Samples are preferred in square shape geometry and can range from 2 mm to 25 mm side length. Example measurements of single-crystal silicon with known doping concentration show the accuracy and reliability of the measurement.
High temperature Hall measurement setup for thin film characterization.
Adnane, L; Gokirmak, A; Silva, H
2016-07-01
Hall measurement using the van der Pauw technique is a common characterization approach that does not require patterning of contacts. Measurements of the Hall voltage and electrical resistivity lead to the product of carrier mobility and carrier concentration (Hall coefficient) which can be decoupled through transport models. Based on the van der Paw method, we have developed an automated setup for Hall measurements from room temperature to ∼500 °C of semiconducting thin films of a wide resistivity range. The resistivity of the film and Hall coefficient is obtained from multiple current-voltage (I-V) measurements performed using a semiconductor parameter analyzer under applied constant "up," zero, and "down" magnetic field generated with two neodymium permanent magnets. The use of slopes obtained from multiple I-Vs for the three magnetic field conditions offer improved accuracy. Samples are preferred in square shape geometry and can range from 2 mm to 25 mm side length. Example measurements of single-crystal silicon with known doping concentration show the accuracy and reliability of the measurement. PMID:27475605
Suitable reverberation times for halls for rock and pop music.
Adelman-Larsen, Niels Werner; Thompson, Eric R; Gade, Anders C
2010-01-01
The existing body of literature regarding the acoustic design of concert halls has focused almost exclusively on classical music, although there are many more performances of popular music, including rock and pop. Objective measurements were made of the acoustics of 20 rock music venues in Denmark and a questionnaire was used in a subjective assessment of those venues with professional rock musicians and sound engineers as expert listeners. Correlations between the measurements show that clarity, including bass frequencies down to 63 Hz, is important for the general impression of the acoustics of the hall. The best-rated halls in the study have reverberation times that are approximately frequency independent from 0.6 to 1.2 s for hall volumes from 1000 to 6000 m(3). The worst rated halls in the study had significantly higher reverberation times in the 63 and 125 Hz bands. Since most audiences at rock concerts are standing, absorption coefficients were measured with a standing audience from 63 Hz to 4 kHz. These measurements showed that a standing audience absorbs about five times as much energy in mid-/high-frequency bands as in low-frequency bands.
Spin Hall effects in mesoscopic Pt films with high resistivity
NASA Astrophysics Data System (ADS)
Qin, Chuan; Luo, Yongming; Zhou, Chao; Cai, Yunjiao; Jia, Mengwen; Chen, Shuhan; Wu, Yizheng; Ji, Yi
2016-10-01
The energy efficiency of the spin Hall effects (SHE) can be enhanced if the electrical conductivity is decreased without sacrificing the spin Hall conductivity. The resistivity of Pt films can be increased to 150-300 µΩ · cm by mesoscopic lateral confinement, thereby decreasing the conductivity. The SHE and inverse spin Hall effects (ISHE) in these mesoscopic Pt films are explored at 10 K by using the nonlocal spin injection/detection method. All relevant physical quantities are determined in situ on the same substrate, and a quantitative approach is developed to characterize all processes effectively. Extensive measurements with various Pt thickness values reveal an upper limit for the Pt spin diffusion length: {λ\\text{pt}} ⩽ 0.8 nm. The average product of {λ\\text{pt}} and the Pt spin Hall angle {α\\text{H}} is substantial: {α\\text{H}}{λ\\text{pt}} = (0.142 ± 0.040) nm for 4 nm thick Pt, though a gradual decrease is observed at larger Pt thickness. The results suggest enhanced spin Hall effects in resistive mesoscopic Pt films.
The microscopic nature of localization in the quantum Hall effect.
Ilani, S; Martin, J; Teitelbaum, E; Smet, J H; Mahalu, D; Umansky, V; Yacoby, A
2004-01-22
The quantum Hall effect arises from the interplay between localized and extended states that form when electrons, confined to two dimensions, are subject to a perpendicular magnetic field. The effect involves exact quantization of all the electronic transport properties owing to particle localization. In the conventional theory of the quantum Hall effect, strong-field localization is associated with a single-particle drift motion of electrons along contours of constant disorder potential. Transport experiments that probe the extended states in the transition regions between quantum Hall phases have been used to test both the theory and its implications for quantum Hall phase transitions. Although several experiments on highly disordered samples have affirmed the validity of the single-particle picture, other experiments and some recent theories have found deviations from the predicted universal behaviour. Here we use a scanning single-electron transistor to probe the individual localized states, which we find to be strikingly different from the predictions of single-particle theory. The states are mainly determined by Coulomb interactions, and appear only when quantization of kinetic energy limits the screening ability of electrons. We conclude that the quantum Hall effect has a greater diversity of regimes and phase transitions than predicted by the single-particle framework. Our experiments suggest a unified picture of localization in which the single-particle model is valid only in the limit of strong disorder.
Anomalous electron mobility in a coaxial Hall discharge plasma.
Meezan, N B; Hargus, W A; Cappelli, M A
2001-02-01
A comprehensive analysis of measurements supporting the presence of anomalous cross-field electron mobility in Hall plasma accelerators is presented. Nonintrusive laser-induced fluorescence measurements of neutral xenon and ionized xenon velocities, and various electrostatic probe diagnostic measurements are used to locally determine the effective electron Hall parameter inside the accelerator channel. These values are then compared to the classical (collision-driven) Hall parameters expected for a quiescent magnetized plasma. The results indicate that in the vicinity of the anode, where there are fewer plasma instabilities, the electron-transport mechanism is likely elastic collisions with the background neutral xenon. However, we find that in the vicinity of the discharge channel exit, where the magnetic field is the strongest and where there are intense fluctuations in the plasma properties, the inferred Hall parameter departs from the classical value, and is close to the Bohm value of (omega(ce)tau)(eff) approximately 16. These results are used to support a simple model for the Hall parameter that is based on the scalar addition of the electron collision frequencies (elastic collision induced plus fluctuation induced), as proposed by Boeuf and Garrigues [J. Appl. Phys. 84, 3541 (1998)]. The results also draw attention to the possible role of fluctuations in enhancing electron transport in regions where the electrons are highly magnetized.
Proximity-Induced Anomalous Hall Effect in Graphene
NASA Astrophysics Data System (ADS)
Wang, Zhiyong; Tang, Chi; Sachs, Raymond; Barlas, Yafis; Shi, Jing
2014-03-01
Pre-patterned graphene devices are transferred from SiO2/Si to atomically flat magnetic insulator thin films, yttrium iron garnet (YIG) deposited by a laser molecular beam epitaxial system on gadolinium gallium garnet (GGG) substrate. Room temperature Raman spectroscopy reveals both single-layer graphene and YIG characteristic peaks. In addition to the ordinary Hall effect, there is a clear non-linear Hall component correlated with the magnetization of the YIG films, which we attribute to the anomalous Hall effect (AHE). The magnitude of AHE in graphene/YIG devices decreases as temperature increases. With device-to-device variations, in some devices, AHE persists to room temperature, indicating a strong proximity-induced exchange interaction. By sweeping top gate voltages, one can tune the carrier density across the Dirac point. We also find that the carrier mobility is not significantly different in graphene/YIG. As the graphene is tuned from the electron- to hole-type, the ordinary Hall changes the sign as expected, but the sign of the AHE contribution remains the same. It suggests that AHE does not simply originate from the carrier density change which is responsible for the ordinary Hall effect, but is related to the spin-orbit interaction in the system. This work was supported in part by DOE and NSF.
Reconnection dynamics with secondary tearing instability in compressible Hall plasmas
Ma, Z. W. Wang, L. C.; Li, L. J.
2015-06-15
The dynamics of a secondary tearing instability is systematically investigated based on compressible Hall magnetohydrodynamic. It is found that in the early nonlinear phase of magnetic reconnection before onset of the secondary tearing instability, the geometry of the magnetic field in the reconnection region tends to form a Y-type structure in a weak Hall regime, instead of an X-type structure in a strong Hall regime. A new scaling law is found that the maximum reconnection rate in the early nonlinear stage is proportional to the square of the ion inertial length (γ∝d{sub i}{sup 2}) in the weak Hall regime. In the late nonlinear phase, the thin elongated current sheet associated with the Y-type geometry of the magnetic field breaks up to form a magnetic island due to a secondary tearing instability. After the onset of the secondary tearing mode, the reconnection rate is substantially boosted by the formation of the X-type geometries of magnetic field in the reconnection regions. With a strong Hall effect, the maximum reconnection rate linearly increases with the increase of the ion inertial length (γ∝d{sub i})
Stability of Hall equilibria in neutron star crusts
Marchant, Pablo; Reisenegger, Andreas; Valdivia, Juan Alejandro; Hoyos, Jaime H.
2014-12-01
In the solid crusts of neutron stars, the advection of the magnetic field by the current-carrying electrons, an effect known as Hall drift, should play a very important role as the ions remain essentially fixed (as long as the solid does not break). Although Hall drift preserves the magnetic field energy, it has been argued that it may drive a turbulent cascade to scales at which ohmic dissipation becomes effective, allowing a much faster decay in objects with very strong fields. On the other hand, it has been found that there are 'Hall equilibria', i.e., field configurations that are unaffected by Hall drift. Here we address the crucial question of the stability of these equilibria through axially symmetric (two-dimensional (2D)) numerical simulations of Hall drift and ohmic diffusion, with the simplifying assumption of uniform electron density and conductivity. We demonstrate the 2D stability of a purely poloidal equilibrium, for which ohmic dissipation makes the field evolve toward an attractor state through adjacent stable configurations, around which damped oscillations occur. For this field, the decay scales with the ohmic timescale. We also study the case of an unstable equilibrium consisting of both poloidal and toroidal field components that are confined within the crust. This field evolves into a stable configuration, which undergoes damped oscillations superimposed on a slow evolution toward an attractor, just as the purely poloidal one.
Optical detection of spin Hall effect in metals
Erve, O. M. J. van ‘t Hanbicki, A. T.; McCreary, K. M.; Li, C. H.; Jonker, B. T.
2014-04-28
Optical techniques have been widely used to probe the spin Hall effect in semiconductors. In metals, however, only electrical methods such as nonlocal spin valve transport, ferromagnetic resonance, or spin torque transfer experiments have been successful. These methods require complex processing techniques and measuring setups. We show here that the spin Hall effect can be observed in non-magnetic metals such as Pt and β-W, using a standard bench top magneto-optical Kerr system with very little sample preparation. Applying a square wave current and using Fourier analysis significantly improve our detection level. One can readily determine the angular dependence of the induced polarization on the bias current direction (very difficult to do with voltage detection), the orientation of the spin Hall induced polarization, and the sign of the spin Hall angle. This optical approach is free from the complications of various resistive effects, which can compromise voltage measurements. This opens up the study of spin Hall effect in metals to a variety of spin dynamic and spatial imaging experiments.
Equivalent Electrical Circuit Representations of AC Quantized Hall Resistance Standards
Cage, M. E.; Jeffery, A.; Matthews, J.
1999-01-01
We use equivalent electrical circuits to analyze the effects of large parasitic impedances existing in all sample probes on four-terminal-pair measurements of the ac quantized Hall resistance RH. The circuit components include the externally measurable parasitic capacitances, inductances, lead resistances, and leakage resistances of ac quantized Hall resistance standards, as well as components that represent the electrical characteristics of the quantum Hall effect device (QHE). Two kinds of electrical circuit connections to the QHE are described and considered: single-series “offset” and quadruple-series. (We eliminated other connections in earlier analyses because they did not provide the desired accuracy with all sample probe leads attached at the device.) Exact, but complicated, algebraic equations are derived for the currents and measured quantized Hall voltages for these two circuits. Only the quadruple-series connection circuit meets our desired goal of measuring RH for both ac and dc currents with a one-standard-deviation uncertainty of 10−8 RH or less during the same cool-down with all leads attached at the device. The single-series “offset” connection circuit meets our other desired goal of also measuring the longitudinal resistance Rx for both ac and dc currents during that same cool-down. We will use these predictions to apply small measurable corrections, and uncertainties of the corrections, to ac measurements of RH in order to realize an intrinsic ac quantized Hall resistance standard of 10−8 RH uncertainty or less.
Spin Hall Conductivity and Spin Chern Number for Dirac Systems
NASA Astrophysics Data System (ADS)
Yunt, Elif; Dayi, Omer Faruk
A semiclassical differential form formalism of the spin Hall effect for Dirac systems is presented. In this formalism, space coordinates and momenta are usual dynamical variables, whereas spin is not a dynamical degree of freedom. Spin depicts itself in the matrix-valuedness of equations of motion. We demonstrate that the main contribution to the spin Hall conductivity is given by the spin Chern number whether the spin is conserved or not at the quantum level. We illustrated the formulation within the Kane-Mele model of graphene in the absence and in the presence of the Rashba spin-orbit coupling term. Kane-Mele Model of graphene, which incorporates intrinsic spin-orbit interaction, constitutes the first example of a two dimensional topological insulator. We established the anomalous Hall conductivity as well as the spin Hall conductivity from the term linear in the electric field and the Berry curvature in the the anamolous velocity term. In a basis where the component of spin under consideration is diagonal this term is diagonal. We argue that this semiclassical procedure of calculating the spin Hall conductivity can be generalized to any dimension.
Concert hall acoustics assessment with individually elicited attributes.
Lokki, Tapio; Patynen, Jukka; Kuusinen, Antti; Vertanen, Heikki; Tervo, Sakari
2011-08-01
Concert hall acoustics was evaluated with a descriptive sensory analysis method by employing an individual vocabulary development technique. The goal was to obtain sensory profiles of three concert halls by eliciting perceptual attributes for evaluation and comparison of the halls. The stimuli were gathered by playing back anechoic symphony music from 34 loudspeakers on stage in each concert hall and recording the sound field with a microphone array. Four musical programs were processed for multichannel 3D sound reproduction in the actual listening test. Twenty screened assessors developed their individual set of attributes and performed a comparative evaluation of nine seats, three in each hall. The results contain the distinctive groups of elicited attributes and show good agreement within assessors, even though they applied individual attributes when rating the samples. It was also found that loudness and distance gave the strongest perceptual direction to the principal component basis. In addition, the study revealed that the perception of reverberance is related to the size of the space or to the enveloping reverberance, depending on the assessor.
Band Collapse and the Quantum Hall Effect in Graphene
Bernevig, B.Andrei; Hughes, Taylor L.; Zhang, Shou-Cheng; Chen, Han-Dong; Wu, Congjun; /Santa Barbara, KITP
2010-03-16
The recent Quantum Hall experiments in graphene have confirmed the theoretically well-understood picture of the quantum Hall (QH) conductance in fermion systems with continuum Dirac spectrum. In this paper we take into account the lattice, and perform an exact diagonalization of the Landau problem on the hexagonal lattice. At very large magnetic fields the Dirac argument fails completely and the Hall conductance, given by the number of edge states present in the gaps of the spectrum, is dominated by lattice effects. As the field is lowered, the experimentally observed situation is recovered through a phenomenon which we call band collapse. As a corollary, for low magnetic field, graphene will exhibit two qualitatively different QHE's: at low filling, the QHE will be dominated by the 'relativistic' Dirac spectrum and the Hall conductance will be odd-integer; above a certain filling, the QHE will be dominated by a non-relativistic spectrum, and the Hall conductance will span all integers, even and odd.
Martin, L. N.; Dmitruk, P.; Gomez, D. O.
2010-11-15
In this work we numerically test a model of Hall magnetohydrodynamics in the presence of a strong mean magnetic field: the reduced Hall magnetohydrodynamic model (RHMHD) derived by [Gomez et al., Phys. Plasmas 15, 102303 (2008)] with the addition of weak compressible effects. The main advantage of this model lies in the reduction of computational cost. Nevertheless, up until now the degree of agreement with the original Hall MHD system and the range of validity in a regime of turbulence were not established. In this work direct numerical simulations of three-dimensional Hall MHD turbulence in the presence of a strong mean magnetic field are compared with simulations of the weak compressible RHMHD model. The results show that the degree of agreement is very high (when the different assumptions of RHMHD, such as spectral anisotropy, are satisfied). Nevertheless, when the initial conditions are isotropic but the mean magnetic field is maintained strong, the results differ at the beginning but asymptotically reach a good agreement at relatively short times. We also found evidence that the compressibility still plays a role in the dynamics of these systems, and the weak compressible RHMHD model is able to capture these effects. In conclusion the weak compressible RHMHD model is a valid approximation of the Hall MHD turbulence in the relevant physical context.
Microwave Hall effect measurements on biological and organic semiconductors
NASA Astrophysics Data System (ADS)
Al-Zoubi, A. Y.; Hasan, O. M.
2005-01-01
Microwave Hall effect measurements have been performed by improved 10 GHz bimodal cavity resonators with hybrid end walls used to avoid the background signal that obscures the measurements on low mobility materials. Hall mobility results on copper phthalocyanines CuPc and other organic semiconductors, in the range of 8 cm2/V s to 60 cm2/V s, provide evidence of acoustic phonon scattering as the dominant conduction mechanism. Presently, the microwave Hall effect seems to represent the only means available for quantitative measurements on biological substances like DNA and proteins, which yield mobility values lower than 10 cm2/V s, and are therefore consistent with conduction mechanism involving hopping of charge carriers between localized energy sites.
Optimization of a wall-less Hall thruster
NASA Astrophysics Data System (ADS)
Vaudolon, Julien; Mazouffre, Stéphane; Hénaux, Carole; Harribey, Dominique; Rossi, Alberto
2015-10-01
An experimental optimization of a Hall thruster in wall-less operation mode is performed with the PPS-Flex, a 1.5 kW class thruster capable of modifying the magnetic field topology over a broad range of configurations. The anode geometry and the magnetic topology have been modified to avoid interaction between the magnetic field lines and the anode surface, compared to the first wall-less Hall thruster prototype. The measurements of the thrust and far-field ion properties reveal that a satisfactory performance level can be obtained once the magnetic barrier is restored, and pave the way towards the development of a high-efficiency wall-less Hall thruster.
Thermal Hall Effect of Spin Excitations in a Kagome Magnet.
Hirschberger, Max; Chisnell, Robin; Lee, Young S; Ong, N P
2015-09-01
At low temperatures, the thermal conductivity of spin excitations in a magnetic insulator can exceed that of phonons. However, because they are charge neutral, the spin waves are not expected to display a thermal Hall effect. However, in the kagome lattice, theory predicts that the Berry curvature leads to a thermal Hall conductivity κ(xy). Here we report observation of a large κ(xy) in the kagome magnet Cu(1-3, bdc) which orders magnetically at 1.8 K. The observed κ(xy) undergoes a remarkable sign reversal with changes in temperature or magnetic field, associated with sign alternation of the Chern flux between magnon bands. The close correlation between κ(xy) and κ(xx) firmly precludes a phonon origin for the thermal Hall effect. PMID:26382691
Novel Hall sensors developed for magnetic field imaging systems.
Cambel, V.; Karapetrov, G.; Novosad, V.; Bartolome, E.; Gregusova, D.; Fedor, J.; Kudela, R.; Soltys, J.; Materials Science Division; Slovak Academy of Sciences; Univ. Autonoma de Barcelona
2007-09-01
We report here on the fabrication and application of novel planar Hall sensors based on shallow InGaP/AlGaAs/GaAs heterostructure with a two-dimensional electron gas (2DEG) as an active layer. The sensors are developed for two kinds of experiments. In the first one, magnetic samples are placed directly on the Hall sensor. Room temperature experiments of permalloy objects evaporated onto the sensor are presented. In the second experiment, the sensor scans close over a multigranular superconducting sample prepared on a YBCO thin film. Large-area and high-resolution scanning experiments were performed at 4.2 K with the Hall probe scanning system in a liquid helium flow cryostat.
Novel Hall sensors developed for magnetic field imaging systems
NASA Astrophysics Data System (ADS)
Cambel, Vladimír; Karapetrov, Goran; Novosad, Valentyn; Bartolomé, Elena; Gregušová, Dagmar; Fedor, Ján; Kúdela, Robert; Šoltýs, Ján
2007-09-01
We report here on the fabrication and application of novel planar Hall sensors based on shallow InGaP/AlGaAs/GaAs heterostructure with a two-dimensional electron gas (2DEG) as an active layer. The sensors are developed for two kinds of experiments. In the first one, magnetic samples are placed directly on the Hall sensor. Room temperature experiments of permalloy objects evaporated onto the sensor are presented. In the second experiment, the sensor scans close over a multigranular superconducting sample prepared on a YBCO thin film. Large-area and high-resolution scanning experiments were performed at 4.2 K with the Hall probe scanning system in a liquid helium flow cryostat.
Carl Gustav Jung and Granville Stanley Hall on Religious Experience.
Kim, Chae Young
2016-08-01
Granville Stanley Hall (1844-1924) with William James (1842-1910) is the key founder of psychology of religion movement and the first American experimental or genetic psychologist, and Carl Gustav Jung (1875-1961) is the founder of the analytical psychology concerned sympathetically about the religious dimension rooted in the human subject. Their fundamental works are mutually connected. Among other things, both Hall and Jung were deeply interested in how the study of religious experience is indispensable for the depth understanding of human subject. Nevertheless, except for the slight indication, this common interest between them has not yet been examined in academic research paper. So this paper aims to articulate preliminary evidence of affinities focusing on the locus and its function of the inner deep psychic dimension as the religious in the work of Hall and Jung. PMID:27094706
Axisymmetric nonlinear waves and structures in Hall plasmas
Islam, Tanim
2012-06-15
In this paper, a general equation for the evolution of an axisymmetric magnetic field in a Hall plasma is derived, with an integral similar to the Grad-Shafranov equation. Special solutions arising from curvature-whistler drift modes that propagate along the electron drift as a Burger's shock and nonlinear periodic and soliton-like solutions to the generalized Grad-Shafranov integral-are analyzed. We derive analytical and numerical solutions in a classical electron-ion Hall plasma, in which electrons and ions are the only species in the plasmas. Results may then be applied to the following low-ionized astrophysical plasmas: in protostellar disks, in which the ions may be coupled to the motion of gases; and in molecular clouds and protostellar jets, in which the much heavier charged dust in a dusty Hall plasma may be collisionally coupled to the gas.
Performance of a Low-Power Cylindrical Hall Thruster
NASA Technical Reports Server (NTRS)
Polzin, Kurt A.; Markusic, Thomas E.; Stanojev, Boris J.; Dehoyos, Amado; Raitses, Yevgeny; Smirnov, Artem; Fisch, Nathaniel J.
2007-01-01
Recent mission studies have shown that a Hall thruster which operates at relatively constant thrust efficiency (45-55%) over a broad power range (300W - 3kW) is enabling for deep space science missions when compared with slate-of-the-art ion thrusters. While conventional (annular) Hall thrusters can operate at high thrust efficiency at kW power levels, it is difficult to construct one that operates over a broad power envelope down to 0 (100 W) while maintaining relatively high efficiency. In this note we report the measured performance (I(sub sp), thrust and efficiency) of a cylindrical Hall thruster operating at 0 (100 W) input power.
Multimodal interaction in real and virtual concert halls
NASA Astrophysics Data System (ADS)
Larsson, Pontus; Västfjäll, Daniel; Kleiner, Mendel
2001-05-01
Recently, researchers within the field of room acoustics have shown an increased interest for the understanding of how different modalities, especially vision and audition, interact in the concert hall experience. Computer auralization and virtual reality technology have brought means to efficiently study such auditory-visual interaction phenomena in concert halls. However, an important question to address is to what extent the results from such studies agree with real, unmediated situations. In this paper, we discuss some of the auditory-visual cross-modal effects discovered in previous experiments, and an account of cross-modal phenomena in room acoustic perception is proposed. Moreover, the importance of measuring simulation fidelity when performing cross-modal experiments in virtual concert halls is discussed. The conclusions are that one can expect auditory-visual interaction effects to occur in both real and virtual rooms, but that simulation fidelity might affect the results when performing experiments in virtual conditions.
Supercurrent in the quantum Hall regime, part II
NASA Astrophysics Data System (ADS)
Amet, Francois; Ke, Chung Ting; Borzenets, Ivan; Wang, Jiyingmei; Watanabe, Kenji; Taniguchi, Takashi; Deacon, Russel; Yamamoto, Michihisa; Bomze, Yuriy; Tarucha, Seigo; Finkelstein, Gleb
A novel promising route for creating topological states and excitations is to combine superconductivity and the quantum Hall effect. Despite this potential, signatures of superconductivity in the quantum Hall regime remain scarce, and a superconducting current through a Landau-quantized two-dimensional electron gas has so far eluded experimental observation. High-mobility graphene/BN heterostructures exhibit the quantum Hall effect at relatively low field and are therefore particularly suitable to study the fate of the Josephson effect in that regime. Here, we report the observation of a superconducting current through graphene at fields as high as 2 Tesla. In that regime, the normal-state resistance is quantized but pockets of superconductivity still persist at small current bias. We will describe their bias and temperature dependence. Magnetic field interference patterns in the supercurrent inform on possible mechanisms mediating this supercurrent.
Spontaneous chiral symmetry breaking of Hall magnetohydrodynamic turbulence.
Meyrand, Romain; Galtier, Sébastien
2012-11-01
Hall magnetohydrodynamics (MHD) is investigated through three-dimensional direct numerical simulations. We show that the Hall effect induces a spontaneous chiral symmetry breaking of the turbulent dynamics. The normalized magnetic polarization is introduced to separate the right- (R) and left-handed (L) fluctuations. A classical k(-7/3) spectrum is found at small scales for R magnetic fluctuations which corresponds to the electron MHD prediction. A spectrum compatible with k(-11/3) is obtained at large-scales for the L magnetic fluctuations; we call this regime the ion MHD. These results are explained heuristically by rewriting the Hall MHD equations in a succinct vortex dynamical form. Applications to solar wind turbulence are discussed.
μHall chip for sensitive detection of bacteria.
Issadore, David; Chung, Hyun Jung; Chung, Jaehoon; Budin, Ghyslain; Weissleder, Ralph; Lee, Hakho
2013-09-01
Sensitive, rapid and phenotype-specific enumeration of pathogens is essential for the diagnosis of infectious disease, monitoring of food chains, and for defense against bioterrorism. Microbiological culture and genotyping, techniques that sensitively and selectively detect bacteria in laboratory settings, have limited application in clinical environments due to high cost, slow response times, and the need for specially trained staff and laboratory infrastructure. To address these challenges, we developed a microfluidic chip-based micro-Hall (μHall) platform capable of measuring single, magnetically tagged bacteria directly in clinical specimens with minimal sample processing. We demonstrated the clinical utility of the μHall chip by enumerating Gram-positive bacteria. The overall detection limit of the system was similar to that of culture tests (~10 bacteria), but the assay time was 50-times faster. This low-cost, single-cell analytical technique is especially well-suited to diagnose infectious diseases in resource-limited clinical settings.
Admittance of multiterminal quantum Hall conductors at kilohertz frequencies
Hernández, C.; Consejo, C.; Chaubet, C.; Degiovanni, P.
2014-03-28
We present an experimental study of the low frequency admittance of quantum Hall conductors in the [100 Hz, 1 MHz] frequency range. We show that the frequency dependence of the admittance of the sample strongly depends on the topology of the contacts connections. Our experimental results are well explained within the Christen and Büttiker approach for finite frequency transport in quantum Hall edge channels taking into account the influence of the coaxial cables capacitance. In the Hall bar geometry, we demonstrate that there exists a configuration in which the cable capacitance does not influence the admittance measurement of the sample. In this case, we measure the electrochemical capacitance of the sample and observe its dependence on the filling factor.
Composed planar Hall effect sensors with dual-mode operation
NASA Astrophysics Data System (ADS)
Mor, Vladislav; Roy, Debangsu; Schultz, Moty; Klein, Lior
2016-02-01
We present a composed planar Hall effect sensor with two modes of operation: (a) an ON mode where the composed sensor responds to magnetic field excitations similarly to the response of a regular planar Hall effect sensor, and (b) an OFF mode where the response is negligible. The composed planar Hall effect sensor switches from the OFF mode to the ON mode when it is exposed to a magnetic field which exceeds a certain threshold determined by the sensor design. The features of this sensor make it useful as a switch triggered by magnetic field and as a sensing device with memory, as its mode of operation indicates exposure to a magnetic field larger than a certain threshold without the need to be activated during the exposure itself.