Greatly enhanced generation efficiency of pure spin currents in Ge using Heusler compound Co2FeSi electrodes

Abstract

We show nonlocal spin transport in n-Ge-based lateral spin-valve devices with highly ordered Co2FeSi/n+-Ge Schottky tunnel contacts. Clear spin-valve signals and Hanle effect curves are demonstrated at low temperatures, indicating the generation, manipulation, and detection of pure spin currents in n-Ge. The obtained spin generation efficiency of ∼0.12 is about two orders of magnitude larger than that for a previously reported device with Fe/MgO tunnel barrier contacts. Considering the spin-related behavior with temperature evolution, we infer that it is necessary to simultaneously demonstrate a high spin generation efficiency and improve the quality of the transport channel to realize Ge-based spintronic devices.