Conversion of Heat into Charge Current by the Spin Wave Anomalous Nernst Effect

TL;DR

This paper demonstrates a novel heat-to-charge conversion mechanism via the spin wave anomalous Nernst effect in ferromagnetic FePt films, involving spin wave excitation and inverse spin Hall effect for voltage generation.

Contribution

It introduces a new spin conversion process combining heat gradients, spin waves, and inverse spin Hall effect in ferromagnetic metals.

Findings

Superposed voltage observed in FePt films due to heat gradient.

Spin waves modulate local magnetization and generate spin currents.

Conversion of spin current to voltage via inverse spin Hall effect.

Abstract

A novel process of spin conversion from a temperature gradient to a transverse voltage is addressed in this paper, viz. the anomalous Nernst effect (ANE) in a ferromagnetic metal. We report that an additional voltage is superposed on the conventional anomalous Nernst voltage in FePt crystalline thin films. The dynamics of the local magnetization is modulated by the heat current and excites spin waves. These generate a conduction electron spin current via s-d coupling, which flows along the temperature gradient, and the spin current is converted to a Nernst voltage by the inverse spin Hall effect.