Large bulk resistivity and surface quantum oscillations in the topological insulator Bi2Te2Se

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 Bi2Te2Se presents a high resistivity exceeding 1 Omega 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 Bi2Te2Se is, to our knowledge, the best material to date for studying the surface quantum transport in a topological insulator.