Interplay of Electron and Nuclear Spin Noise in GaAs

TL;DR

This study investigates the complex interactions between electron and nuclear spins in ultrapure GaAs:Si using spin noise spectroscopy, revealing detailed dynamics and finite Overhauser shifts at zero magnetic field.

Contribution

It provides the first detailed measurement of electron and nuclear spin noise spectra in donor-bound electrons in ultrapure GaAs:Si across a wide temporal range.

Findings

Detection of finite Overhauser shift at zero magnetic field

Observation of nuclear spin fluctuation dynamics at low frequencies

Agreement of experimental results with a developed spin noise model

Abstract

We present spin noise (SN) measurements on an ensemble of donor-bound electrons in ultrapure GaAs:Si covering temporal dynamics over six orders of magnitude from milliseconds to nanoseconds. The SN spectra detected at the donor-bound exciton transition show the multifaceted dynamical regime of the ubiquitous mutual electron and nuclear spin interaction typical for III-V based semiconductor systems. The experiment distinctly reveals the finite Overhauser-shift of an electron spin precession at zero external magnetic field and a second contribution around zero frequency stemming from the electron spin components parallel to the nuclear spin fluctuations. Moreover, at very low frequencies features related with time-dependent nuclear spin fluctuations are clearly resolved making it possible to study the intricate nuclear spin dynamics at zero and low magnetic fields. The findings are in agreement with the developed model of electron and nuclear SN.