Report

Quantum Oscillations and Hall Anomaly of Surface States in the Topological Insulator Bi2Te3

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Science  29 Jul 2010:
1189792
DOI: 10.1126/science.1189792

Abstract

Topological insulators are insulating materials that display massless, Dirac-like surface states in which the electrons have only one spin degree of freedom on each surface. These states have been imaged by photoemission, but little information on their transport parameters (e.g., mobility) is available. We report the observation of Shubnikov-de Haas oscillations arising from the surface states in nonmetallic crystals of Bi2Te3. In addition, we uncovered a Hall anomaly in weak fields, which enables the surface current to be seen directly. Both experiments yield a surface mobility (9,000 – 10,000 cm2/Vs), that is significantly higher than in the bulk. The Fermi velocity of 4 × 105 m/s obtained from these transport experiments agrees with angle-resolved photoemission experiments.