Spin dynamics and fluctuations in the streaming regime

TL;DR

This paper theoretically investigates the spin dynamics and fluctuations of two-dimensional electrons in the streaming regime under moderate electric fields, revealing anisotropic relaxation and quasi-periodic dependence of spin mode relaxation times.

Contribution

It introduces a detailed theoretical model of spin dynamics in the streaming regime, highlighting the superposition of spin modes and their spectral signatures.

Findings

Spin relaxation times depend quasi-periodically on inverse electric field.

Spin noise spectrum features narrow low-frequency peaks and satellite peaks.

Spin modes can be detected via spin noise spectroscopy.

Abstract

Spin dynamics of two-dimensional electrons in moderate in-plane electric fields is studied theoretically. The streaming regime is considered, where each electron accelerates until reaching the optical phonon energy, then it emits an optical phonon, and a new period of acceleration starts. Spin-orbit interaction and elastic scattering result in anisotropic relaxation of electron spin polarization. The overall spin dynamics is described by a superposition of spin modes in the system. The relaxation time of the most long-living mode depends quasi-periodically on the inverse electric field. The spin modes can be conveniently revealed by means of spin noise spectroscopy. It is demonstrated that the spectrum of spin fluctuations consists of peaks with the low-frequency peak much narrower than satellite ones, and the widths of the peaks are determined by the decay times of the modes.