Observation of the spin Nernst effect

TL;DR

This paper reports the first experimental observation of the spin Nernst effect in platinum, demonstrating a pure transverse spin current generated by a temperature gradient, with implications for spin transport understanding.

Contribution

It provides the first experimental evidence of the spin Nernst effect, linking it to the spin Hall effect and confirming theoretical predictions.

Findings

Spin Nernst and spin Hall effects in Pt are of comparable magnitude.

The spin Nernst and spin Hall effects differ in sign.

Experimental results agree with first-principles calculations.

Abstract

The observation of the spin Hall effect triggered intense research on pure spin current transport. With the spin Hall effect, the spin Seebeck effect, and the spin Peltier effect already observed, our picture of pure spin current transport is almost complete. The only missing piece is the spin Nernst (-Ettingshausen) effect, that so far has only been discussed on theoretical grounds. Here, we report the observation of the spin Nernst effect. By applying a longitudinal temperature gradient, we generate a pure transverse spin current in a Pt thin film. For readout, we exploit the magnetization-orientation-dependent spin transfer to an adjacent Yttrium Iron Garnet layer, converting the spin Nernst current in Pt into a controlled change of the longitudinal thermopower voltage. Our experiments show that the spin Nernst and the spin Hall effect in Pt are of comparable magnitude, but differ in sign, as corroborated by first-principles calculations.