Electrical and thermal spin accumulation in germanium

TL;DR

This paper demonstrates electrical and thermal spin accumulation in germanium at room temperature, showing how gate voltage and temperature gradients influence spin signals and their potential for spintronic applications.

Contribution

It reports the first electrical spin injection in germanium at room temperature and explores thermal spin accumulation driven by temperature gradients without charge current.

Findings

Electrical spin injection in germanium is achieved at room temperature.

Thermal spin accumulation can be generated by temperature gradients.

Spin signals are modulated by gate voltage and are consistent with diffusion models.

Abstract

In this letter, we first show electrical spin injection in the germanium conduction band at room temperature and modulate the spin signal by applying a gate voltage to the channel. The corresponding signal modulation agrees well with the predictions of spin diffusion models. Then by setting a temperature gradient between germanium and the ferromagnet, we create a thermal spin accumulation in germanium without any tunnel charge current. We show that temperature gradients yield larger spin accumulations than pure electrical spin injection but, due to competing microscopic effects, the thermal spin accumulation in germanium remains surprisingly almost unchanged under the application of a gate voltage to the channel.