Temperature dependence of the nonlocal voltage in an Fe/GaAs electrical spin injection device

TL;DR

This study investigates how temperature affects the nonlocal spin resistance in Fe/GaAs devices, revealing that annealing modifies the temperature dependence and unexpectedly enhances spin transfer efficiency in minority-spin injection samples.

Contribution

It demonstrates the temperature dependence of spin resistance in Fe/GaAs devices and shows how annealing alters spin transfer efficiency and decay rates.

Findings

Spin resistance persists up to room temperature in nonannealed samples.

Annealing increases low-temperature spin signals but also increases decay rate.

Annealing modifies the temperature dependence of spin transfer efficiency.

Abstract

The nonlocal spin resistance is measured as a function of temperature in a Fe/GaAs spin-injection device. For nonannealed samples that show minority-spin injection, the spin resistance is observed up to room temperature and decays exponentially with temperature at a rate of 0.018\,K$^{-1}$. Post-growth annealing at 440\,K increases the spin signal at low temperatures, but the decay rate also increases to 0.030\,K$^{-1}$. From measurements of the diffusion constant and the spin lifetime in the GaAs channel, we conclude that sample annealing modifies the temperature dependence of the spin transfer efficiency at injection and detection contacts. Surprisingly, the spin transfer efficiency increases in samples that exhibit minority-spin injection.