Heat-driven spin transport in a ferromagnetic metal

TL;DR

This paper investigates heat-driven spin transport in ferromagnetic metals, highlighting the interplay of spin currents and thermoelectric effects, and emphasizes the importance of separating different voltage contributions in experiments.

Contribution

It reveals that the ferromagnetic metal itself generates a significant voltage due to additional spin currents, clarifying the interpretation of spin Seebeck effect measurements in metallic systems.

Findings

Identification of voltage contributions from multiple effects

Demonstration of the ferromagnet's own voltage generation

Clarification of spin current effects in metallic ferromagnets

Abstract

As a non-magnetic heavy metal is attached to a ferromagnet, a vertically flowing heat-driven spin current is converted to a transverse electric voltage, which is known as the longitudinal spin Seebeck effect (SSE). If the ferromagnet is a metal, this voltage is also accompanied by voltages from two other sources, i.e. the anomalous Nernst effect in both the ferromagnet and the proximity-induced ferromagnetic boundary layer. By properly identifying and carefully separating those different effects, we find that in this pure spin current circuit the additional spin current drawn by the heavy metal generates another significant voltage by the ferromagnetic metal itself which should be present in all relevant experiments.