The valley Nernst effect in WSe 2

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 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 good agreement with the predicted value. Atomically thin transition metal dichalcogenides possess a valley degree of freedom, which could enrich the physics underpinning the conventional Nernst effect observed in traditional solids. Here, the authors report experimental evidence of the valley Nernst effect in WSe2 at room temperature.