Slowing down of spin relaxation in two dimensional systems by quantum interference effects

TL;DR

This paper investigates how quantum interference effects, specifically weak localization, slow down spin relaxation in two-dimensional systems with spin-split spectra, revealing a power-law decay of spin polarization over time.

Contribution

It introduces a theoretical framework incorporating weak localization as nonlocal-in-time corrections to spin dynamics, highlighting the role of nonbackscattering contributions and magnetic field effects.

Findings

Spin relaxation slows down due to interference of electron waves along closed paths.

Spin polarization decays as 1/t at large times due to weak localization.

Magnetic fields suppress the power-law tail in spin polarization.

Abstract

The effect of weak localization on spin relaxation in a two-dimensional system with a spin-split spectrum is considered. It is shown that the spin relaxation slows down due to the interference of electron waves moving along closed paths in opposite directions. As a result, the averaged electron spin decays at large times as $1/t$. It is found that the spin dynamics can be described by a Boltzmann-type equation, in which the weak localization effects are taken into account as nonlocal-in-time corrections to the collision integral. The corrections are expressed via a spin-dependent return probability. The physical nature of the phenomenon is discussed and it is shown that the "nonbackscattering" contribution to the weak localization plays an essential role. It is also demonstrated that the magnetic field, both transversal and longitudinal, suppresses the power tail in the spin polarization.