The Nuclear Spin Environment in Lateral GaAs Spin Valves

TL;DR

This study uses a lateral GaAs spin valve to explore nuclear spin relaxation, revealing long T1 times and unconventional temperature dependence, advancing understanding of spin-environment interactions in solid-state systems.

Contribution

It provides new measurements of nuclear spin relaxation times at very low temperatures and discusses relaxation mechanisms in disordered conductors near the metal-insulator transition.

Findings

Nuclear T1 times up to 3 hours at 100 mK.

Sub-linear temperature dependence of relaxation rates.

Contrast with traditional Korringa relaxation in metals.

Abstract

The spin degree of freedom in solids offers opportunities beyond charge-based electronics and is actively investigated for both spintronics and quantum computation. However, the interplay of these spins with their native environment can give rise to detrimental effects such as spin relaxation and decoherence. Here, we use an all-electrical, lateral GaAs spin valve to manipulate and investigate the inherent nuclear spin system. Hanle satellites are used to determine the nuclear spin relaxation rates for the previously unexplored temperature range down to 100 mK, giving T1 times as long as 3 hours. Despite metallic temperature dependence of resistivity, the observed relaxation rates show a sub-linear temperature dependence. This contrasts the Korringa relaxation mechanism observed in metals but is not inconsistent with hyperfine-mediated relaxation in a disordered, interacting conductor not far from the metal-insulator transition. We discuss possible relaxation mechanisms and further investigate inhomogeneities in the nuclear spin polarization.