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arXiv · 1210.4477

Evidence for a direct band gap in the topological insulator Bi2Se3 from theory and experiment

I. A. Nechaev·R. C. Hatch·M. Bianchi·D. Guan·C. Friedrich·I. Aguilera·J. L. Mi·B. B. Iversen·S. Blügel·Ph. Hofmann·E. V. Chulkov
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Abstract

Using angle-resolved photoelectron spectroscopy and ab-initio GW calculations, we unambiguously show that the widely investigated three-dimensional topological insulator Bi2Se3 has a direct band gap at the Gamma point. Experimentally, this is shown by a three-dimensional band mapping in large fractions of the Brillouin zone. Theoretically, we demonstrate that the valence band maximum is located at the Brillouin center only if many-body effects are included in the calculation. Otherwise, it is found in a high-symmetry mirror plane away from the zone center.

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I. A. Nechaev, R. C. Hatch, M. Bianchi, D. Guan, C. Friedrich, I. Aguilera, J. L. Mi, B. B. Iversen, S. Blügel, Ph. Hofmann, E. V. Chulkov. 2012-10-16. Evidence for a direct band gap in the topological insulator Bi2Se3 from theory and experiment. https://doi.org/10.1103/physrevb.87.121111

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