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HL: Fachverband Halbleiterphysik

HL 31: Focus Session: Dirac fermions in solid-state systems (HL, jointly with TT)

HL 31.3: Topical Talk

Dienstag, 12. März 2013, 10:30–11:00, H2

First-principles studies of Dirac-cones in graphene and 3D topological insulators — •Gustav Bihlmayer — Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, Jülich, Germany

The unique properties of graphene, in particular the two Dirac-cones determining the transport phenomena in this material, led the way to the first theoretical proposal of the quantum spin Hall effect at the edges of a graphene ribbon by Kane and Mele in 2005. Since spin-orbit coupling (SOC) effects are extremely weak at the Dirac points, this phenomenon is hard to observe experimentally. I discuss several theoretical proposals and experiments that have been made to enhance intrinsic SOC effects. Here, density functional theory (DFT) provides a quantitative tool to predict the properties of these two-dimensional topological insulator phases.

In three-dimensional topological insulators topologically protected edge states form Dirac-cones with chiral spin texture (in contrast to the spin-degenerate Dirac-cone of graphene). We discuss the spin-polarization and -orientations in this state for Bi and Se chalcogenides and its interaction and modification with magnetic adatoms. Also here DFT results will be compared to experiments where available.