Photoemission-induced gating of topological insulators

The recently discovered topological insulators exhibit topologically protected metallic surface states which are interesting from the fundamental point of view and could be useful for various applications if an appropriate electronic gating can be realized. Our photoemission study of Cu-intercalated Bi2Se3 shows that the surface-state occupancy in this material can be tuned by changing the photon energy and understood as a photoemission-induced gating effect. Our finding provides an effective tool to investigate the new physics coming from the topological surface states and suggests intercalation as a recipe for synthesis of a material suitable for electronic applications.