Valley photothermoelectric effects in transition-metal dichalcogenides

We theoretically investigate photothermoelectric effects, i.e., the photoenabled versions of the Seebeck and Nernst effects in monolayer transition metal dichalcogenides (TMDCs) using semiclassical transport theory. We find that monolayer TMDCs subjected to circular polarized light show anomalous thermoelectric properties as a result of strong spin-orbit interaction and broken inversion symmetry. The Seebeck coefficient for photogenerated carriers is relatively large and changes its sign at a critical carrier density. In addition, a nontrivial photo-Nernst effect emerges in the absence of an external magnetic field or magnetic moments.