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

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.

8 pages, 4 figures

References in corpus (14)

• Topological Insulators
• Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface
• First observation of Spin-Momentum Helical Locking in Bi2Se3 and Bi2Te3, demonstration of Topological-Order at 300K and a realization of topological-transport-regime
• Coexistence of the topological state and a two-dimensional electron gas on the surface of Bi2Se3
• Observation of topological order in a Superconducting doped topological insulator (based on the Bi2Se3 class)
• Large tuneable Rashba spin splitting of a two-dimensional electron gas in Bi2Se3
• Efficient implementation of the GW approximation within the all-electron FLAPW method
• Persistence of Topological Order and Formation of Quantum Well States in Topological Insulators Bi2(Se,Te)3 under Ambient Conditions
• Simultaneous quantization of bulk conduction and valence states through adsorption of nonmagnetic impurities on Bi2Se3
• Quasiparticle Effects in the Bulk and Surface-State Bands of Bi2Se3 and Bi2Te3 Topological Insulators
• Surface Scattering via Bulk Continuum States in the 3D Topological Insulator Bi${}_2$Se${}_3$
• Stability of the Bi2Se3(111) topological state: electron-phonon and -defect scattering
• New interpretation of the origin of 2DEG states at the surface of layered topological insulators
• The electronic structure of clean and adsorbate-covered Bi2Se3: an angle-resolved photoemission study

Cited by in corpus (46)

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• Emergent Momentum-Space Skyrmion Texture on the Surface of Topological Insulators
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