Room-temperature spin injection and spin-to-charge conversion in a ferromagnetic semiconductor / topological insulator heterostructure

TL;DR

This paper demonstrates for the first time room-temperature spin injection and spin-to-charge conversion in a ferromagnetic semiconductor/topological insulator heterostructure, using spin pumping and inverse spin Hall effect detection.

Contribution

It introduces a novel room-temperature spin injection method in a (Ga,Fe)Sb/BiSb heterostructure, combining ferromagnetic semiconductor and topological insulator properties.

Findings

Successful detection of spin injection at room temperature.

Large inverse spin Hall angle of 2.5 in BiSb surface states.

First demonstration of spin-to-charge conversion in this heterostructure.

Abstract

Spin injection using ferromagnetic semiconductors at room temperature is a building block for the realization of spin-functional semiconductor devices. Nevertheless, this has been very challenging due to the lack of reliable room-temperature ferromagnetism in well-known group IV and III-V based semiconductors. Here, we demonstrate room-temperature spin injection by using spin pumping in a (Ga,Fe)Sb / BiSb heterostructure, where (Ga,Fe)Sb is a ferromagnetic semiconductor (FMS) with high Curie temperature (TC) and BiSb is a topological insulator (TI). Despite the very small magnetization of (Ga,Fe)Sb at room temperature (45 emu/cc), we are able to detect spin injection from (Ga,Fe)Sb by utilizing the inverse spin Hall effect (ISHE) in the topological surface states of BiSb with a large inverse spin Hall angle of 2.5. Our study provides the first demonstration of spin injection as well as spin-to-charge conversion at room temperature in a FMS/TI heterostructure.