Nernst Plateau in the Quantum Limit of Low-Carrier-Density Topological Insulators

Nernst effect, a transverse electric current induced by a temperature gradient, is a promising tool for revealing emergent phases of condensed matter. We find a Nernst coefficient plateau in low carrier density topological insulators, as a signature of 1D Weyl points in the quantum limit of the weak topological insulator. The plateau height is inversely proportional to the impurity density, suggesting a way to engineer infinitely large Nernst effects. The Nernst plateau also exists in strong topological insulators, at the bottom of the lowest Landau band. We show that these plateaus have been overlooked in the previous experiments and we highlight the experimental conditions to observe them. Our results may inspire more investigations of employing anomalous Nernst effect to identify emergent phases of condensed matter.