Manipulation of spin dephasing in InAs quantum wires

The spin dephasing due to the Rashba spin-orbit coupling, especially its dependence on the direction of the electric field is studied in InAs quantum wire. We find that the spin dephasing is strongly affected by the angle of Rashba effective magnetic field and the applied magnetic field. The nonlinearity in spin dephasing time versus the direction of the electric field shows a potential evenue to manipulate the spin lifetime in spintronic device. Moreover, we figure out a quantity that can well represent the inhomogeneous broadening of the system which may help us to understand the many-body spin dephasing due to the Rashba effect.Comment: 4 pages, 3 figure

Spin dynamics in high-mobility two-dimensional electron systems

Understanding the spin dynamics in semiconductor heterostructures is highly important for future semiconductor spintronic devices. In high-mobility two-dimensional electron systems (2DES), the spin lifetime strongly depends on the initial degree of spin polarization due to the electron-electron interaction. The Hartree-Fock (HF) term of the Coulomb interaction acts like an effective out-of-plane magnetic field and thus reduces the spin-flip rate. By time-resolved Faraday rotation (TRFR) techniques, we demonstrate that the spin lifetime is increased by an order of magnitude as the initial spin polarization degree is raised from the low-polarization limit to several percent. We perform control experiments to decouple the excitation density in the sample from the spin polarization degree and investigate the interplay of the internal HF field and an external perpendicular magnetic field. The lifetime of spins oriented in the plane of a [001]-grown 2DES is strongly anisotropic if the Rashba and Dresselhaus spin-orbit fields are of the same order of magnitude. This anisotropy, which stems from the interference of the Rashba and the Dresselhaus spin-orbit fields, is highly density-dependent: as the electron density is increased, the kubic Dresselhaus term becomes dominant and reduces the anisotropy.Comment: 13 pages, 6 figure

Spin oscillations in transient diffusion of a spin pulse in n-type semiconductor quantum wells

By studying the time and spatial evolution of a pulse of the spin polarization in $n$-type semiconductor quantum wells, we highlight the importance of the off-diagonal spin coherence in spin diffusion and transport. Spin oscillations and spin polarization reverse along the the direction of spin diffusion in the absence of the applied magnetic field are predicted from our investigation.Comment: 5 pages, 4 figures, accepted for publication in PR

Spin-dependent hole quantum transport in Aharonov-Bohm ring structure: possible schemes for spin filter

We study the Aharonov-Bohm (AB) effect in two-dimensional mesoscopic frame in hole systems. We show that differing from the AB effect in electron systems, due to the presence of both the heavy hole and the light hole, the conductances not only show the normal spin-unresolved AB oscillations, but also become spin-separated. Some schemes for spin filter based on the abundant interference characteristics are proposed.Comment: 4 pages, 5 figures. Phys. Lett. A, 2005, in pres

Spin-orbit coupling in bulk GaAs

We study the spin-orbit coupling in the whole Brillouin zone for GaAs using both the $sp^3s^{\ast}d^5$ and $sp^3s^{\ast}$ nearest-neighbor tight-binding models. In the $\Gamma$-valley, the spin splitting obtained is in good agreement with experimental data. We then further explicitly present the coefficients of the spin splitting in GaAs $L$ and $X$ valleys. These results are important to the realization of spintronic device and the investigation of spin dynamics far away from equilibrium.Comment: 8 pages, 3 figures, Physica E, in pres

Spin dynamics in semiconductors

This article reviews the current status of spin dynamics in semiconductors which has achieved a lot of progress in the past years due to the fast growing field of semiconductor spintronics. The primary focus is the theoretical and experimental developments of spin relaxation and dephasing in both spin precession in time domain and spin diffusion and transport in spacial domain. A fully microscopic many-body investigation on spin dynamics based on the kinetic spin Bloch equation approach is reviewed comprehensively.Comment: a review article with 193 pages and 1103 references. To be published in Physics Reports

Spin dynamics of Rashba-Dresselhaus two-dimensional electron systems with electron-electron interactions

Spin dynamics of Rashba-Dresselhaus two-dimensional electron systems is studied by taking account of electron-electron interactions under the D’yakonov-Perel’ mechanism. The diffusion equations for charge and spin densities are obtained through decoupling of the interactions using the auxiliary Bose field. We show that the electron-electron interaction has no effect on the infinite spin lifetime when the Rashba and Dresselhaus coupling constants satisfy the condition α=±β. If the general condition α≠±β is satisfied, the spin lifetime is finite and enhanced by the electron-electron interaction with the increment of the temperature in the ballistic regime. The increasing amplitude of the spin lifetime depends on the ratio of the temperature to the Fermi temperature. Copyright EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg 2010