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An enhancement in the power-conversion-efficiency (η) of a magneto-electric (ME) gyrator has been found by the use of Mn-substituted nickel zinc ferrite. A trilayer gyrator of Mn-doped Ni0.8Zn0.2Fe2O3 and Pb(Zr,Ti)O3 has η=85% at low power conditions (~20 mW/in3) and η≥80% at high power conditions (~5W/in3). It works close to fundamental electromechanical resonance in both direct and converse modes. The value of g is by far the highest reported so far, which is due to the high mechanical quality factor (Qm) of the magnetostrictive ferrite. Such highly efficient ME gyrators with a significant power density could become important elements in power electronics, potentially replacing electromagnetic and piezoelectric transformers. [ABSTRACT FROM AUTHOR]

Phase retrieval is an important tool with broad applications in optics. The Gerchberg–Saxton algorithm has been a workhorse in this area for many years. The algorithm extracts phase information from intensities captured in two planes related by a Fourier transform. The ability to capture the two intensities in domains other than the image and Fourier plains adds flexibility; various authors have extended the algorithm to extract phase from intensities captured in two planes related by other optical transforms, e.g., by free space propagation or a fractional Fourier transform. These generalizations are relatively simple once a unitary discrete transform is available to propagate back and forth between the two measurement planes. In the absence of such a unitary transform, errors accumulate quickly as the algorithm propagates back and forth between the two planes. Unitary transforms are available for many separable systems, but there has been limited work reported on nonseparable systems other than the gyrator transform. In this letter, we simulate a nonseparable system in a unitary way by choosing an advantageous sampling rate related to the system parameters. We demonstrate a simulation of phase retrieval from intensities in the image domain and a second domain related to the image domain by a nonseparable linear canonical transform. This work may permit the use of nonseparable systems in many design problems. [ABSTRACT FROM PUBLISHER]

We have investigated the power conversion and loss processes in magnetoelectric gyrators. Two types of loss mechanisms were identified by using a transformer-gyrator structure, which transfers power between magnetic and magnetomechanical forms. A missing portion of the power in a gyrator was then identified to be a returned power from the load resistor under low drive conditions. Under high drive conditions, decreases in both the magnetostriction and mechanical quality factor resulted in additional inefficiencies. Power transfer efficiencies of greater than 70% and 50% were achieved for magnetoelectric (ME) gyrators based on Metglas/Pb(Zr,Ti)O3 laminated composites under low power drive and high power density drive (60 W/in.³) conditions, respectively. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the magnetotransport properties of the Ge0.743Pb0.183Mn0.074Te mixed crystal. The results of magnetization measurements indicated that the compound is a spin-glass-like diluted magnetic semiconductor with critical temperature TSG = 97.5 K. Nanoclusters in the sample are observed. Both, matrix and clusters are magnetically active. Resistivity as a function of temperature has a minimum at 30 K. Below the minimum a variable-range hopping is observed, while above the minimum a metallic-like behavior occurs. The crystal has high hole concentration, p = 6.6×1020 cm-3, temperature-independent. Magnetoresistance amplitude changes from –0.78 to 1.18% with increase of temperature. In the magnetotransport measurements we observed the anomalous Hall effect with hysteresis loops. Calculated anomalous Hall effect coeffcient, RS = 2.0 × 106 m3/C, is temperature independent. The analysis indicates the extrinsic skew scattering mechanism to be the main physical mechanism responsible for anomalous Hall effect in Ge0.743Pb0.183Mn0.074Te alloy. [ABSTRACT FROM AUTHOR]

The translational mode of a vortex confined in a soft magnetic Fe19Ni81 circular disk and an elliptically shaped dot causes an asymmetric response in the rectifying planar Hall voltage and dc voltage output spectra. The symmetry breaking of these spectra has been experimentally observed, and is controlled by the simultaneous application of radio-frequency current and direct current. We can qualitatively explain the asymmetry of the rectifying spectra by the nonlinear resonator model, with gyration within a large radius around the vortex equilibrium positions causing the asymmetry. [ABSTRACT FROM AUTHOR]

A Hamiltonian to describe a spin quantum Hall effect with two types of spin-orbit coupling is introduced and the eigenfunctions and eigenvalues are obtained for it. It is shown that this Hamiltonian also results by gauging a kinetic energy Hamiltonian by an SU (2) gauge field. The Berry phase is obtained from the model wavefunction for the model and used to define a filling factor. This allows for the calculation of the spin Hall conductivity. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [ABSTRACT FROM AUTHOR]

In this paper, we focus on the connection between spin Hall effect and spin force. Here we investigate that the spin force due to spin-orbit coupling, which, in two-dimensional system, is equivalent to forces of Hirsch and Chudnovsky besides constant factors 3 and $\frac{3}{2}$ respectively, is a part of classic Anandan force, and that the spin Hall effect is an anomalous Hall effect. Furthermore, we develop the method of AC phase to derive the expression for the spin force, and note that the most basic spin Hall effect indeed originate from the AC phase and is therefore an intrinsic quantum mechanical property of spin. This method differs from approach of Berry phase in the study of anomalous Hall effect , which is the intrinsic property of the perfect crystal. On the other hand, we use an elegant skill to show that the Chudnovsky-Drude model is reasonable. Here we have improved the theoretical values of spin Hall conductivity of Chudnovsky. Compared to the theoretical values of spin Hall conductivity in the Chudnovsky-Drude model, ours are in better agreement with experimentation. Finally, we discuss the relation between spin Hall effect and fractional statistics. [ABSTRACT FROM AUTHOR]

Steady magnetohydrodynamic flow of an incompressible micropolar fluid through a pipe of circular cross-section is studied by considering Hall and ionic effects. The fluid motion is due to a constant pressure gradient, and an external uniform magnetic field directed perpendicular to the flow direction is applied. Expressions for the velocity, microrotation, skin friction and flow rate are obtained. The effects of the micropolar parameter, magnetic parameter, Hall parameter and ion-slip parameter on the velocity, microrotation, skin friction and flow rate are discussed. [ABSTRACT FROM AUTHOR]

Double quantum wells (DQWs) were first implemented in the InAs/AlSb heterosystem, which is characterized by a large Landé g factor |g|=15 of the InAs layers forming the well, much larger than the bulk g factor |g|=0.4 of the GaAs in conventional GaAs/AlGaAs DQWs. The quality of the samples is good enough to permit observation of a clear picture of the quantum Hall effect (QHE). Despite the small tunneling gap, which is due to the large barrier height (1.4 eV), features with odd filling factors ν=3,5,7,... are present in the QHE, due to collectivized interlayer states of the DQW. When the field is rotated relative to the normal to the layers, the ν=3 state is suppressed, confirming the collectivized nature of that state and denying that it could owe its existence to a strong asymmetry of the DQW. Previously the destruction of the collectivized QHE states by a parallel field had been observed only for the ν=1 state. The observation of a similar effect for ν=3 in an InAs/AlSb DQW may be due to the large bulk g factor of InAs. [ABSTRACT FROM AUTHOR]

Abstract: Geometrical optics is extended so as to provide a model for spinning light rays via the coadjoint orbits of the Euclidean group characterized by color and spin. This leads to a theory of “geometrical spinoptics” in refractive media. Symplectic scattering yields generalized Snell–Descartes laws that include the recently discovered optical Hall effect. [Copyright &y& Elsevier]

The erosion rate of a Hall thruster was estimated with the objective of building a real-time erosion rate monitoring system using a 1 kW class anode layer type Hall thruster. This system aids the understanding of the tradeoff between lifetime and performance. To estimate the flux of the sputtered wall material, the number density of the sputtered iron was measured by laser absorption spectroscopy using an absorption line from ground atomic iron at 371.9935 nm. An ultravioletAlxInyGa(1-x-y)N diode laser was used as the probe. The estimated number density of iron was 1.1×1016 m-3, which is reasonable when compared with that measured by duration erosion tests. The relation between estimated erosion rate and magnetic flux density also agreed with that measured by duration erosion tests. [ABSTRACT FROM AUTHOR]

We review our previous “exotic” particle, together with the more recent anomalous anyon model (which has the arbitrary gyromagnetic factor g). The nonrelativistic limit of the anyon generalizes the exotic particle with g = 0 to any g. In a planar electromagnetic field, the Hall effect becomes mandatory for all g ≠ 2 when the field takes some critical value. [ABSTRACT FROM AUTHOR]

Temperature and magnetic field dependence of the Hall effect in the normal and mixed state of fully textured (Hg0.9Re0.1)Ba2CaCu2O6+δ (HgRe-1212) HTSC thin films prepared by laser ablation deposition have been studied. The longitudinal resistivity ρxx and Hall resistivity ρyx of HgRe-1212 superconductor thin films were measured for a wide range of magnetic fields from 125mT to 12T with the field perpendicular to the ab plane and the current in the ab plane. A sign change of the Hall resistivity is observed in fields below 3T in the region close to the superconducting onset temperature. The temperature dependencies ρxx∝T and ρyx∝1/T have been observed for HgRe-1212 thin films. The Hall angle θH relation cotθH=αT2+β, remains valid for temperatures T between Tc and 200K. In the mixed state a power-law behavior is observed, where ρyx scales to a power-law function of ρxx: , with β increasing from 1.0 to 1.7 as the field increases from 1 to 12T. [Copyright &y& Elsevier]

We study the edge state of atomic Hall fluids. It is described by a chiral 1D bosonic field theory and the atomic excitations are a type of bosonic Luttinger liquid. We investigate the dynamical property of edge state and propose an experiment to measure the topological number, which could be verified experimentally in future. [ABSTRACT FROM AUTHOR]

The Hall effect has been measured in the V-doped La1.85Sr0.15Cu1−xVxO4+δ system for the temperature 50–300 K. In all samples 1/RH varies linearly with temperature. Carrier density decreases as the V content x increases in a 1/x manner. Tc* (=Tc/Tcmax) decreases with the increase of V content and can be roughly described as Tc*=1−C((1/RH)opt−(1/RH))4. [Copyright &y& Elsevier]

High-temperature superconductivity is achieved by doping copper oxide insulators with charge carriers. The density of carriers in conducting materials can be determined from measurements of the Hall voltage-the voltage transverse to the flow of the electrical current that is proportional to an applied magnetic field. In common metals, this proportionality (the Hall coefficient) is robustly temperature independent. This is in marked contrast to the behaviour seen in high-temperature superconductors when in the ‘normal’ (resistive) state; the departure from expected behaviour is a key signature of the unconventional nature of the normal state, the origin of which remains a central controversy in condensed matter physics. Here we report the evolution of the low-temperature Hall coefficient in the normal state as the carrier density is increased, from the onset of superconductivity and beyond (where superconductivity has been suppressed by a magnetic field). Surprisingly, the Hall coefficient does not vary monotonically with doping but rather exhibits a sharp change at the optimal doping level for superconductivity. This observation supports the idea that two competing ground states underlie the high-temperature superconducting phase. [ABSTRACT FROM AUTHOR]

For high–Tc superconductor metal oxides (HTSC) it is shown that the dc resistivity and Hall effect temperature behaviour can be explained by the model of the paraelectric material close to the point of the Mott-Hubbard instability, in the ground state of which the current is carried by a liquid of boson-like pairs of carriers in upper and lower Hubbard bands. The Mott-Hubbard instability corresponds to the order-of-lattice-constant length of the mean free path and results in the temperature insensitivity of Drude conductivity. Nearly linear on T resistivity results from the Curie law via the local (acting) electric field. Fermion-like carriers, temperature excited over the energy of boson-like pair dissociation (pseudo gap), explain the temperature behaviour of Hall effect. Available data are compared with the model. [ABSTRACT FROM AUTHOR]

An improvement of the neutral gas injection in order to increase the Hall thruster lifetime capabilities is demonstrated using a two-dimensional model. An additional atom injection through the channel ceramics in a region located between the ionization and the acceleration zones leads to an efficient ionization of the neutral flux, with a flattening of the plasma density and potential profiles in the radial direction. Thanks to this modified injection of the atom flow, a focusing electric field is produced, reducing the ion flux impacting on ceramic walls. [ABSTRACT FROM AUTHOR]

Zinc oxide-based extrinsic composite was investigated. The sample was selected from a series of components of one production batch, prepared by standard sintering technology. The content of extrinsic elements in ZnO base was determined by SEM. Van der Pauw method with four-point electrode fixture was used for study of conducting phenomena in square-shaped sample. It is normaly preferred to assume the symmetric uniformity of the electrical properties of sample, for which sheet resistance, bulk resistivity and Hall mobility, sheet carrier density and carrier concentration can be calculated. When the uniformity of measured parameters is breached, the anisotropy in the arrangement of the internal structure may be the cause. There remains the question of whether the extrinsic ZnO material can be isotropic, regarding the electrical conductivity. Although the Hall effect has been measured, preliminary measurements indicate the presence of anisotropy in the measured samples. Before measurement the following phenomena should be taken into account: magneto-electric effect, photo-electric effect and the isothermal condition should be preserved. Paper discusses the uniformity deviations for the defined setup configurations for positive and negative magnetic field directions. Bulk resistivity has been calculated by numerical solution of van der Pauw equation. Large offset voltage during the measurement is discussed. [ABSTRACT FROM AUTHOR]

The article presents a study that determines the effectiveness of quantum spin Hall effect (QSHE) in predicting the topological non-trivial surfaces. It explores the method of the study in which it identifies the spin-polarized nature of the edge states of a QSHE system, as well as the potential difference between spin-up and spin-down electrons. The study indicates the usefulness of QSHE in discovering topological insulators and establishing spin-polarized character of quantum spin Hall edge.

We report on the electric control of the magnetic anisotropy in an ultrathin ferromagnetic (Ga,Mn)As/(Ga,Mn)(As,P) bilayer with competing in-plane and out-of-plane anisotropies. The carrier distribution and therefore the strength of the effective anisotropy are controlled by the gate voltage of a field effect device. Anomalous Hall effect measurements confirm that a depletion of carriers in the upper (Ga,Mn)As layer results in the decrease of the in-plane anisotropy. The uniaxial anisotropy field is found to decrease by a factor ∼4 over the explored gate-voltage range so that the transition to an out-of-plane easy-axis configuration is almost reached. [ABSTRACT FROM AUTHOR]