Large bulk resistivity and surface quantum oscillations in the topological insulator Bi 2 Te 2 Se

Topological insulators are predicted to present interesting surface transport phenomena but their experimental studies have been hindered by a metallic bulk conduction that overwhelms the surface transport. We show that the topological insulator ${\text{Bi}}_{2}{\text{Te}}_{2}\text{Se}$ presents a high resistivity exceeding $1\text{ }\ensuremath{\Omega}\text{ }\text{cm}$ and a variable-range hopping behavior, and yet presents Shubnikov-de Haas oscillations coming from the topological surface state. Furthermore, we have been able to clarify both the bulk and surface transport channels, establishing a comprehensive understanding of the transport in this material. Our results demonstrate that…