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Dresden 2011 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 63: Poster II (Surface Magnetism/ Magnetic Imaging/ Topological Insulators/ Spin Structures and Magnetic Phase Transitions/ Graphene/ Magnetic Thin Films/ Magnetic Semiconductors/ Magnetic Half-metals and Oxides/ Spin-dependent Transport/ Spin Excitations and Spin Torque/ Spin Injection and Spin Currents in Heterostructures/ Spintronics/ Magnetic Storage and Applications)

MA 63.15: Poster

Freitag, 18. März 2011, 11:00–14:00, P2

Bulk vs. surface effects in ARPES experiments on the topological insulator Bi2Se3 — •Richard C. Hatch1, Marco Bianchi1, Dandan Guan1,2, Shining Bao2, Jianli Mi3, Bo Brummerstedt Iversen3, and Philip Hofmann11Department of Physics and Astronomy, Interdisciplinary Nanoscience Center Århus University, 8000 Århus C, Denmark — 2Department of Physics, Zhejiang University, Hangzhou, 310027 China — 3Department of Chemistry, Interdisciplinary Nanoscience Center, Århus University, 8000 Århus C, Denmark

While the bulk of a topological insulator is insulating, fundamental symmetry considerations require the surfaces to be metallic. The dimensionality of states in the topological insulator Bi2Se3 were probed directly by performing ARPES measurements at different photon energies along ΓK and ΓM. It was found that both the topological surface state and the state attributed to a two-dimensional electron gas [1] do not disperse with respect to the wave vector perpendicular to the surface kz—thus confirming their two-dimensional nature. In contrast, strong kz dispersions of the bulk conduction and valence bands are evident. From the experimental data, we derive the bulk band structure in the two high-symmetry slices throughout the Brillouin zone. Finally, we observe a state at a binding energy of 750 meV which does not disperse with kz and is interpreted to be another surface state situated in a projected bulk band gap below the upper valence band.

[1] M. Bianchi et al. Nat. Communications 2010, DOI 10.1038/NComms1131.

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