Spin-Hall effect in the generalized honeycomb lattice with Rashba spin-orbit interaction

We study the spin-Hall effect in a generalized honeycomb lattice, which is described by a tight-binding Hamiltonian including the Rashba spin-orbit coupling and inversion-symmetry breaking terms brought about by a uniaxial pressure. The calculated spin-Hall conductance displays a series of exact or approximate plateaus for isotropic or anisotropic hopping integral parameters, respectively. We show that these plateaus are a consequence of the various Fermi-surface topologies when tuning epsilon(F). For the isotropic case, a consistent two-band analysis, as well as a Berry-phase interpretation. are also given. (C) 2009 Elsevier B.V. All rights reserved.

Spin Hall effect on the kagome lattice with Rashba spin-orbit interaction

We study the spin Hall effect in the kagome lattice with Rashba spin-orbit coupling. The conserved spin Hall conductance sigma(s)(xy) (see text) and its two components, i.e., the conventional term sigma(s0)(xy) and the spin-torque-dipole term sigma(s tau)(xy), are numerically calculated, which show a series of plateaus as a function of the electron Fermi energy epsilon(F). A consistent two-band analysis, as well as a Berry-phase interpretation, is also given. We show that these plateaus are a consequence of various Fermi-surface topologies when tuning epsilon(F). In particular, we predict that compared to the case with the Fermi surface encircling the Gamma point in the Brillouin zone, the amplitude of the spin Hall conductance with the Fermi surface encircling the K points is twice enhanced, which makes it highly meaningful in the future to systematically carry out studies of the K-valley spintronics.

Measurement of single electron spin with submicron Hall magnetometer

Submicron Hall magnetometry has been demonstrated as an efficient technique to probe extremely weak magnetic fields. In this letter, we analyze the possibility of employing it to detect single electron spin. Signal strength and readout time are estimated and discussed with respect to a number of practical issues. (C) 2005 American Institute of Physics.

Spin Hall effect of excitons with spin-orbit coupling

The center-of-mass motion of a quasi-two-dimensional exciton with spin-orbit coupling (SOC) in the presence of a perpendicular electric field is calculated by perturbation theory. The results indicate that a quasi-two-dimensional exciton with SOC can exhibit the spin Hall effect (SHE), which is similar to two-dimensional electrons and holes. A likely way to establish exciton SHE in experiments and a possible phase transition from dark to bright state driven by SOC are suggested. (c) 2007 American Institute of Physics.

Effect of small-angle scattering on the integer quantum Hall plateau

A GaAs/AlGaAs two-dimensional electron gas (2 DEG) structure with the high mobility of mu(2K) = 1.78 x 10(6) cm(2)/Vs has been studied by low-temperature Hall and Shubnikov de Hass (SdH) measurements. Quantum lifetimes related to all-angle scattering events reduced from 0.64 ps to 0.52 ps after illuminating by Dingle plots, and transport lifetimes related to large-angle scattering events increasing from 42.3 ps to 67.8 ps. These results show that small-angle scattering events become stronger. It is clear that small-angle scattering events can cause the variation of the widths of the quantum Hall plateaus.

Characteristics of InAs epilayers for Hall effect devices grown on GaAs substrates by MBE

InAs thin films with good characteristics were grown on GaAs (0 0 1) substrates by molecular beam epitaxy. Cross-sectional transmission electron microscopy indicated that most of the threading dislocations formed by the interaction of misfit dislocations are annihilated above a small thickness. The high electron mobility and small temperature dependence of InAs epilayers are useful for magnetic sensors which is demonstrated by the properties of Hall effect devices.

Cyclotron resonance and quantum Hall effect studies of the two-dimensional electron gas confined at the GaN/AlGaN interface

We report on high magnetic fields (up to 40 T) cyclotron resonance, quantum Hall effect and Shubnikov-de-Hass measurements in high frequency transistors based on Si-doped GaN-AlGaN heterojunctions. A simple way of precise modelling of the cyclotron absorption in these heterojunctions is presented, We clearly establish two-dimensional electrons to be the dominant conducting carriers and determine precisely their in-plane effective mass to be 0.230 +/- 0.005 of the free electron effective mass. The increase of the effective mass with an increase of two-dimensional carrier density is observed and explained by the nonparabolicity effect. (C) 1997 American Institute of Physics.

高线性度外延及注入GaAs Hall器件

讨论了外延及注入制作的薄层GaAs Hall器件如何获得高的磁线性度。GaAs Hall器件的磁线性度在高磁场下会有偏离，但可以通过外延及注入的过渡层对有源区进行补偿，在合适的有源区和过渡区的浓度和厚度分布中，可以得到在2.5T的强磁场下，±0.04%的高磁线性度。

半绝缘砷化镓Hall测量中的若干问题

建立了绝缘电阻大于10~(13)Ω和温度起伏小于0.1℃的半绝缘砷化镓Hall测量装置。研究了环境温度、湿度、漏电流、数据读取时间、测量电压、样品尺寸等因素对电阻率与迁移率的影响，并讨论了各种因素所引起的测量误差。

MBE生长的InAs薄膜Hall器件

利用GaAs衬底上的InAa薄膜制备的Hall器件，具有灵敏度高(在相同的电子浓度、室温附近灵敏度是GaAs Hall器件的1.5倍)，不等位电压温漂小等优点。可用于电流传感器、无刷电机等磁敏传感器中，具有广阔的应用前景。

InAs薄膜Hall器件

于2010-11-23批量导入

InAs薄膜Hall器件的材料生长与特性研究

报道了利用InAs外延薄膜制作霍尔器件，通过分子束外延技术在GaAs衬底上生长的InAs薄膜具有较高的迁移率和较好的温度特性。用这种材料制作的霍尔器件在每千欧姆内阻条件下灵敏度与GaAs平面Hall器件相比提高了50%。

A 3 Tesla Superconducting Magnet for Hall Sensor Calibration

A 3 T superconducting magnet with a 70 mm diameter warm bore and energy storage of 47 kJ has been successfully fabricated and tested, which can be used to calibrate Hall sensors in high magnetic field as well as conduct superconducting experiments. The magnet consists of three solenoid coils and an iron yoke. The homogeneity of the magnetic field in the region of interest (ROI) is +/- 6.0 x 10(-5). The coils of the magnet were fabricated with NbTi-Cu superconducting wire and the stray magnetic field is shielded by an iron yoke. The coils and yoke are fully immersed in a helium vessel. The optimized structural design, stress and quench simulation, fabrication and test results are presented in this paper.