The valley Nernst effect in WSe$_2$

TL;DR

This paper reports the experimental observation of the valley Nernst effect in WSe$_2$, demonstrating a temperature-gradient-induced valley current detectable at room temperature, aligning well with theoretical predictions.

Contribution

It provides the first experimental evidence of the valley Nernst effect in WSe$_2$, utilizing spin-valley coupling and spin pumping techniques.

Findings

Valley Nernst effect detected electrically at room temperature.

Valley Nernst coefficient matches theoretical predictions.

Method demonstrates control of valley polarization via temperature gradients.

Abstract

The Hall effect can be extended by inducing a temperature gradient in lieu of electric field that is known as the Nernst (-Ettingshausen) effect. The recently discovered spin Nernst effect in heavy metals continues to enrich the picture of Nernst effect-related phenomena. However, the collection would not be complete without mentioning the valley degree of freedom benchmarked by the observation of the valley Hall effect. Here we show the experimental evidence of its missing counterpart, the valley Nernst effect. Using millimeter-sized WSe$_{2}$ mono-multi-layers and the ferromagnetic resonance-spin pumping technique, we are able to apply a temperature gradient by off-centering the sample in the radio frequency cavity and address a single valley through spin-valley coupling. The combination of a temperature gradient and the valley polarization leads to the valley Nernst effect in WSe$_{2}$ that we detect electrically at room temperature. The valley Nernst coefficient is in very good agreement with the predicted value.