Spin dephasing in quantum wires

Abstract

We study high-field spin transport in a quantum wire using a semiclassical approach. Spin dephasing (or spin depolarization) in the wire is caused by D'yakonov-Perel' relaxation associated with bulk inversion asymmetry (Dresselhaus spin-orbit coupling) and structural inversion asymmetry (Rashba spin-orbit coupling). The depolarization rate is found to depend strongly on the initial polarization of the spin. If the initial polarization is along the axis of the wire, the spin depolarizes \ensuremath{\sim}100 times slower compared to the case when the initial polarization is transverse to the wire axis. We also find that in the range 4.2\char21{}50 K, temperature has a weak influence and the driving electric field has a strong influence on the depolarization rate. The steady state distribution of the spin components parallel and transverse to the wire axis also depend on the initial polarization. If the initial polarization is along the wire axis, then the steady state distribution of both components is a flat-topped uniform distribution, whereas if the initial polarization is transverse to the wire axis, then the distribution of the longitudinal component resembles a Gaussian, and the distribution of the transverse component is U shaped.