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HL: Fachverband Halbleiterphysik

HL 29: Poster Session: Spintronics; Spin-controled transport; Topological insulators; Interfaces / Surfaces; Magnetic semiconductors

HL 29.21: Poster

Montag, 11. März 2013, 16:00–20:00, Poster A

Group theoretical and topological analysis of the band structure of silicene — •Florian Geißler¹, Jan Carl Budich², and Björn Trauzettel¹ — ¹Institute for Theoretical Physics and Astrophysics, University of Würzburg, 97074 Würzburg, Germany — ²Department of Physics, Stockholm University, Se-106 91 Stockholm, Sweden

Silicene is a monolayer of silicon atoms in a buckled honeycomb structure. It was recently shown, that a perpendicular electric field is able to couple to the sublattice pseudospin, allowing to electrically tune and close the band gap. Increasing electric fields may therefore generate a topological phase transition from a topological insulator to a normal insulator or semimetal. We perform a group theoretical analysis to systematically construct the Hamiltonian at the K-points of silicene by symmetries only. We discuss, that when further lowest-order terms are respected, the parameter space exhibiting a topological insulator phase is reduced. This is analyzed by an explicit calculation of the topological invariant of the underlying bandstructure.