Effect of structure anisotropy on low temperature spin dynamics in quantum wells

TL;DR

This paper theoretically investigates how structural anisotropy influences low-temperature spin dynamics in quantum wells, revealing quantum beats in spin polarization and their damping mechanisms under various conditions.

Contribution

It introduces a theoretical model analyzing spin dynamics in asymmetric quantum wells, highlighting the effects of anisotropy, temperature, and magnetic fields on spin beats.

Findings

Quantum beats occur in spin polarization due to spin precession.

Beats are damped at zero temperature with combined bulk and structural asymmetry.

Magnetic fields increase beat frequency and promote collision-dominated regimes.

Abstract

Spin dynamics of two-dimensional electron gas confined in an asymmetrical quantum well is studied theoretically in the regime where the scattering frequency is comparable with the spin precession frequency due to the conduction band spin splitting. The spin polarization is shown to demonstrate quantum beats. If the spin splitting is determined by both bulk and structural asymmetry mechanisms the beats are damped at zero temperature even in the absence of a scattering. We calculate the decay of spin beats due to the thermal broadening of the electron distribution function and electron scattering. The magnetic field applied along the structure growth axis is shown to increase the frequency of the beats and shift system towards the collision dominated regime.