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TT: Fachverband Tiefe Temperaturen

TT 55: TR: Topological Insulators 1 (jointly with HL and MA)

TT 55.1: Talk

Thursday, March 17, 2011, 16:00–16:15, HSZ 304

Topological phases in three-dimensional superconductors — •Andreas Schnyder — Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany

We examine different topological phases in three-dimensional non-centrosymmetric superconductors with time-reversal symmetry by using three different types of topological invariants. Due to the bulk boundary correspondence, a non-zero value of any of these topological numbers indicates the appearance of zero-energy Andreev surface states. In fully gapped phases the presence of these surface states is independent of the surface orientation, whereas in nodal superconducting phases the Andreev states appear only for certain orientations of the surface. We find that some of these boundary modes in nodal superconducting phases are dispersionless, i.e., they form a flat surface band. These dispersionless Andreev surface bound states have many observable consequences. In particular, they lead to a zero-bias conductance peak in the scanning tunneling spectra. Furthermore, we discuss the appearance of surface Majorana modes in gapless superconducting phases.