Jungiusstr. 11, Hörsaal AP
SFB 668 - Kolloquium
Dr. G. Bihlmayer (Forschungszentrum Jülich):
Rashba-physics and topologically protected edge states
Electrons, that are confined at the edge of a crystal, move in a potential gradient or electric field. Relativistic effects induce Rashba-type spin-splittings in these states, demonstrated for many surfaces and quantum-well systems. In insulating systems, only these spin-split states contribute to the conductivity. If these states give rise to an odd number of Fermi contours, topologically protected spin-currents arise at the edges, leading to the quantum spin-Hall (QSH) effect. Whether this situation arises or not is already determined by the bulk bandstructure of the material and in many cases bandstructure calculations can easily reveal whether a given material is a topological insulator or not. I will discuss this phenomenon from a surface-science point of view, showing density-functional theory calculations of different material classes, e.g. elemental cases Sb and Bi, their chalcogenides and thallium based compounds.