Spin relaxation in low-dimensional systems

TL;DR

This paper reviews recent advances in understanding spin dynamics in low-dimensional GaAs/GaAlAs quantum wells, highlighting excitonic effects, spin degeneracy breaking, and electron spin depolarization mechanisms.

Contribution

It provides new insights into exciton-exciton interactions and spin depolarization rates in doped quantum wells, expanding knowledge of spin behavior in low-dimensional systems.

Findings

Exciton-exciton interactions break spin degeneracy in 2D semiconductors.

Spin depolarization rate is unaffected by electron kinetic energy.

Thermal spreading accelerates electron spin depolarization.

Abstract

We review some of the newest findings on the spin dynamics of carriers and excitons in GaAs/GaAlAs quantum wells. In intrinsic wells, where the optical properties are dominated by excitonic effects, we show that exciton-exciton interaction produces a breaking of the spin degeneracy in two-dimensional semiconductors. In doped wells, the two spin components of an optically created two-dimensional electron gas are well described by Fermi-Dirac distributions with a common temperature but different chemical potentials. The rate of the spin depolarization of the electron gas is found to be independent of the mean electron kinetic energy but accelerated by thermal spreading of the carriers.