Quantum Oscillations and Hall Anomaly of Surface States in the Topological Insulator Bi 2 Te 3

Abstract

Carrier Mobility in Topological Insulators In addition to an energy gap, which is a characteristic of all band insulators, the electronic structure of the recently discovered three-dimensional topological insulators Bi 2 Te 3 and Bi 2 Se 3 contains a surface state with a Dirac-like dispersion. This state is predicted to be associated with high carrier mobility. However, the transport properties of the surface state are obscured by the bulk material and challenging to measure. Qu et al. (p. 821 , published online 29 July) produced crystals of Bi 2 Te 3 with the Fermi energy lying in the bulk gap and detected quantum oscillations whose magnetic field dependence reveals that they come from a two-dimensional Fermi surface. An anomaly in the Hall conductance originating from the surface state was also observed. The two measurements independently yield mutually consistent high electron mobilities.