Signatures of dynamically polarized nuclear spins in all-electrical lateral spin transport devices

TL;DR

This paper investigates how nuclear spins influence all-electrical lateral spin transport in Fe/GaAs devices at low temperatures, revealing hyperfine interactions and nuclear spin dynamics through experimental and simulation methods.

Contribution

It demonstrates the impact of dynamically polarized nuclear spins on spin signals and introduces a Monte Carlo simulation to model hyperfine interactions in spin transport.

Findings

Nuclear spins modify non-local spin signals below 50 K.

Hyperfine coupling causes satellite peaks in Hanle measurements.

Simulation results align with experimental observations.

Abstract

The effect of nuclear spins in Fe/GaAs all-electrical spin-injection devices is investigated. At temperatures below 50 K, strong modifications of the non-local spin signal are found that are characteristic for hyperfine coupling between conduction electrons and dynamically polarized nuclear spins. The perpendicular component of the nuclear Overhauser field depolarizes electron spins near zero in-plane external magnetic field, and can suppress such dephasing when antialigned with the external field, leading to satellite peaks in a Hanle measurement. The features observed agree well with a Monte Carlo simulation of the spin diffusion equation including hyperfine interaction, and are used to study the nuclear spin dynamics and relate it to the spin polarization of injected electrons.