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TT: Fachverband Tiefe Temperaturen

TT 48: Superconductivity: Heterostructures, Andreev Scattering, Proximity Effect, Vortices

TT 48.5: Vortrag

Freitag, 30. März 2012, 10:30–10:45, H 2053

Proximity effect in semiconductor films with spin-splitting and spin-orbit interaction — •Jens Michelsen and Roland Grein — Institut für Theoretische Festkörperphysik, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany

Superconducting heterostructures with spin-active materials have emerged as promising platforms for engineering topological superconductors featuring Majorana bound states at surfaces, edges and vortices. Here we present a method for evaluating, from a microscopic model, the band structure of a semiconductor film of finite thickness deposited on top of a conventional superconductor. Analytical expressions for the proximity induced gap openings are presented in terms of microscopic parameters and the proximity effect in presence of spin-orbit and exchange splitting is visualized in terms of Andreev reflection processes. An expression for the topological invariant, associated with the existence of Majorana bound states, is shown to depend only on parameters of the semiconductor film. The finite thickness of the film leads to resonant states in the film giving rise to a complex band structure with the topological phase alternating between trivial and non-trivial as the parameters are tuned of the film are tuned.