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.
@article{arxiv.1204.4384,
title = {Electrical and thermal spin accumulation in germanium},
author = {A. Jain and C. Vergnaud and J. Peiro and J. C. Le Breton and E. Prestat and L. Louahadj and C. Portemont and C. Ducruet and V. Baltz and A. Marty and A. Barski and P. Bayle-Guillemaud and L. Vila and J. -P. Attané and E. Augendre and H. Jaffrès and J. -M. George and M. Jamet},
journal= {arXiv preprint arXiv:1204.4384},
year = {2015}
}