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We theoretically explore dwell time for electrons in a semiconductor microstructure, which is constructed on the surface of the InAs/Al x In1- x As heterostructure by patterning a ferromagnetic (FM) stripe and a Schottky-metal (SM) stripe in a parallel configuration. Dwell time is found to be dependent on electron spins. Spin-polarized dwell time can be controlled by changing an applied voltage to SM stripe. Thus, electron spins can be separated in time dimension, and such a semiconductor microstructure can be used as an electrically tunable temporal spin splitter for spintronics device applications.

We have theoretically investigated the control of wave-vector filtering (WVF) by introducing δ-doping into a magnetically modulated nanostructure fabricated by depositing ferromagnetic stri...

We report a theoretical investigation on Goose-Hänchen (GH) effect for spin electrons across a magnetically confined GaAs/AlxGa1-xAs microstructure modulated by spin-orbit coupling [(SOC), including Rashba and Dresselhaus types]. An intrinsic symmetry in the device is broken by SOC, which gives rise to a considerable spin polarization effect in GH shifts of electrons. Both magnitude and direction of spin polarization can be manipulated by Rashba or Dresselhaus SOC, i.e., interfacial confining electric field or strain engineering. Based on such a semiconductor microstructure, a controllable spatial spin splitter can be proposed for spintronics applications.

Semiconductor-based magnetoresistance (MR) device has many advantages such as high MR ratio at low switching magnetic field, but electron spins were ignored completely in previous researches. Electron spins should impact on performance of semiconductor-based MR device, as electron spins interact with magnetic fields. By considering a semiconductor microstructure constructed on GaAs/AlxGa1-xAs heterostructure by patterning two asymmetric ferromagnetic (FM) stripes, we theoretically explore effect of electron spins on semiconductor-based MR device. An interesting spin splitting effect is found in semiconductor-based MR device. Both magnitude and sign of spin splitting effect can be modified by applying a negative voltage. These findings may be helpful for designing semiconductor-based MR devices.

The magnetically confined semiconductor heterostructure (MCSH) is often used as the momentum filter due to an essentially 2-D process for the electronic tunneling. Taking a typical MCSH into account, we theoretically investigate how to manipulate such momentum filters by the $\delta $ -doping technique. The momentum-filtering efficiency can be tuned because of the $\delta $ -doping dependence of the electron transmission. The involved MCSH can be employed as a controllable momentum filter.

A magnetoresistance (MR) device was proposed by depositing two parallel ferromagnetic stripes on top and bottom of a semiconductor heterostructure [Solid State Commun. 141 (2007) 248]. In order to manipulate its performance, we dope a tunable δ-potential into the device by atomic layer doping technique. Transmission, conductance and MR ratio are calculated for the δ-doped MR device. It is confirmed that an obvious MR effect still exists in the device even though a δ-doping is comprised. Results show that the MR ratio varies intensely with the weight and/or the position of the δ-doping. Therefore, one can manipulate structurally the MR device by altering the δ-doping, and a tunable MR device can be obtained for magnetic information storage.

We report on a theoretical study of the giant magnetoresistance (GMR) effect in a δ -doped magnetically confined semiconductor heterostructure nanostructure (MCSHN), which can be realized by depositing two nanosized ferromagnetic (FM) stripes on top and bottom of the semiconductor heterostructure and using the atomic layer doping technique. It is shown that such a nanosystem shows up a sizable GMR effect due to a significant discrepancy in transmission of parallel (P) and antiparallel (AP) magnetization configurations. It is also shown that the MR ratio varies sensitively with the weight and/or position of the δ -doping. Thus, one can conveniently tailor the degree of GMR effect by tuning the δ -doping, and such a nanosystem can be employed as a controllable GMR device for magnetic information storage.

A controllable spin filter is proposed by theoretically investigating spin polarization in a magnetic microstructure constructed on surface of GaAs/AlxGa1-xAs heterostructure by patterning a horizontally-magnetized ferromagnetic stripe. Due to a broken intrinsic symmetry by spin-orbit coupling, a spin polarization effect appears in the magnetic microstructure. Degree of spin polarization can be modified by changing strength of spin-orbit coupling, which may be helpful for design of controllable spin-polarized source.

We investigate the Goos–Hanchen (GH) effect of spin electron beams in a magnetic-barrier (MB) nanostructure consisting of antiparallel double δ - MBs , which can be experimentally realized by depositing two ferromagnetic (FM) stripes on top and bottom of the semiconductor heterostructure. GH shifts for spin electron beams across this type of MB nanostructures, is derived exactly, with the help of the stationary phase method. It is shown that GH shifts depend strongly on the spin directions for double δ - MBs with unidentical magnetic strengths, giving rise to a considerable spin polarization effect. It also is shown that spin polarization of GH shifts is closely relative to the separation and magnetic-strength difference of two δ - MBs . These interesting properties may provide an alternative scheme to spin-polarize electrons into the semiconductor, and the devices can serve as tunable spin beam splitters.

Recently, an electron-spin filter was proposed by depositing a nanosized ferromagnetic metal stripe and a Schottky normal metal stripe on the top of the semiconductor heterostructure [F. Zhai, H. Q. Xu and Y. Guo, Phys. Rev. B70 (2004) 085308]. This device has a considerable electron-spin polarization and potential application in spintronics. Here we apply a bias to this device and theoretically demonstrate how to manipulate its electron-spin polarization. By numerical simulations, we found that not only the amplitude of the electron-spin polarization but also its sign varies with the bias, giving rise to a bias-tunable spin filter device.

We propose a giant magnetoresistance (GMR) device, which can be experimentally realized by depositing two ferromagnetic (FM) strips and a Schottky metal (SM) stripe in parallel configuration on top of the GaAs heterostructure. The GMR effect ascribes a significant electron transmission difference between the parallel and antiparallel magnetization configurations of two FM stripes. Moreover, the MR ratio depends strongly on the magnetic strength of the magnetic barrier (MB) and the electric barrier (EB) height induced by an applied voltage to the SM stripe. Thus, this system can be used as a GMR device with tunable MR by an applied voltage to SM stripe or by magnetic strength of the MB.

We report a theoretical study on spin-polarized transport in a δ-doped magnetic-electric-barrier nanostructure, which can be realized in experiments by depositing two ferromagnetic stripes on top and bottom of a semiconductor heterostructure under an applied voltage and by using atomic layer doping technique. The spin-polarized behavior of the electron in this device is found to be quite sensitive to the δ-doping. One can conveniently tune the degree of the electron spin polarization by adjusting the weight and/or position of the δ-doping. Thus, the involved nansosystem can be employed as a controllable spin filter, which may be helpful for exploiting new spin-polarized source for spintronics applications.

With the help of stationary phase method, we investigate the Goos-Hanchen (GH) effect of electrons in nanostructures consisting of realistic magnetic barriers (MB) created by lithographic patterning of ferromagnetic (FM) or superconducting films. Due to intrinsic symmetry, only nanostructures with symmetric magnetic field possess a considerable spin-dependent GH effect, and GH shifts of transmitted spin beams are found to depend upon the incident angle and the incident energy of electrons as well as the size and position of the FM stripe. These interesting properties may provide an effective scheme to realize spin injection into semiconductor and also give rise to a type of spin beam splitters based on MB nanostructures.

We propose a giant magnetoresistance (GMR) device by depositing nanosized ferromagnetic (FM) and Schottky normal metal (SM) stripes on the top of the GaAs heterostructure. It is shown that this device possesses a considerable GMR effect, whose magnetoresistance (MR) ratio can be up to 106% at a certain energy. It is also shown that the MR ratio depends strongly on the structural parameters and the electrical barrier height induced by the applied voltage to the SM stripe, and thus this device can be used as a tunable GMR device.

The giant magnetoresistance (GMR) effect in a device, composed of nanosized ferromagnetic (FM)-Schottky metals (SM) and semiconductor heterostructure, is investigated theoretically. Experimentally, this GMR device can be realized by the deposition of two parallel FM strips and a SM stripe on the top of a GaAs heterostructure. It is shown that the GMR effect ascribes a significant electron transmission difference between the parallel and antiparallel magnetization configurations of two FM stripes in the device. It is also shown that the magnetoresistance (MR) ratio depends strongly on the magnetic intensity of the magnetic barrier (MB) and the electric-barrier (EB) height induced by an applied voltage to the SM stripe. Thus, this device can be used as a tunable GMR one, whose MR ratio can be switched by adjusting the applied voltage under the SM stripe or by changing the magnetic strength of the MB.