Thermoelectric Imaging of Topological Edge States in a Twisted Bilayer Graphene

Topological insulators have been studied to make high-efficiency thermoelectric devices, but microscopic thermoelectric properties of topological edge states remain to be explored at room temperature. Here, we report on the thermoelectric properties of the topologically protected helical edge states in twisted bilayer graphene. The boundaries of the Bernal stacked domain in twisted bilayer graphene show variation in thermoelectricity depending on the location of the Fermi level and topologically protected helical edge states when the Fermi level is controlled by back-gate voltage. Our results not only deepen our understanding of twisted bilayer graphene’s unique electric and thermoelectric properties but also provide research way of high-performance thermoelectric devices.