Electron Spin Dynamics in Semiconductors without Inversion Symmetry

TL;DR

This paper provides a microscopic analysis of electron spin relaxation in non-centrosymmetric semiconductors, deriving Bloch equations and relaxation times T_1 and T_2 based on the D'yakonov-Perel' mechanism, with specific results for bulk and quantum well structures.

Contribution

It introduces a fully microscopic two-step calculation method for spin relaxation, deriving Bloch equations and relaxation times from first principles.

Findings

In bulk semiconductors without magnetic field, T_1 equals T_2.

In quantum wells with magnetic field along the growth direction, T_1 is half of T_2.

Derived microscopic relaxation times match known experimental behaviors.

Abstract

We present a microscopic analysis of electron spin dynamics in the presence of an external magnetic field for non-centrosymmetric semiconductors in which the D'yakonov-Perel' spin-orbit interaction is the dominant spin relaxation mechanism. We implement a fully microscopic two-step calculation, in which the relaxation of orbital motion due to electron-bath coupling is the first step and spin relaxation due to spin-orbit coupling is the second step. On this basis, we derive a set of Bloch equations for spin with the relaxation times T_1 and T_2 obtained microscopically. We show that in bulk semiconductors without magnetic field, T_1 = T_2, whereas for a quantum well with a magnetic field applied along the growth direction T_1 = T_2/2 for any magnetic field strength.