Observation of the Spin-Seebeck Effect in a Ferromagnetic Semiconductor

TL;DR

This paper reports the experimental observation of the spin-Seebeck effect in a ferromagnetic semiconductor, GaMnAs, demonstrating thermally induced spin currents without charge transport, and highlighting its local nature across magnetic phase transitions.

Contribution

First demonstration of the spin-Seebeck effect in a ferromagnetic semiconductor, enabling flexible control and detailed study of spin caloritronic phenomena.

Findings

Spin-Seebeck effect observed in GaMnAs without charge transport

Effect persists across magnetic phase transition

Spatial distribution of spin currents remains intact across electrical breaks

Abstract

The spin-Seebeck effect was recently discovered in a metallic ferromagnet and consists of a thermally generated spin distribution that is electrically measured utilizing the inverse spin Hall effect. Here this effect is reproduced experimentally in a ferromagnetic semiconductor, GaMnAs, which allows for flexible design of the magnetization directions, a larger spin polarization, and measurements across the magnetic phase transition. The spin-Seebeck effect in GaMnAs is observed even in the absence of longitudinal charge transport. The spatial distribution of spin-currents is maintained across electrical breaks highlighting the local nature of the effect, which is therefore ascribed to a thermally induced spin redistribution.