Würzburg ToCoTronics Colloquium

In this talk, we will discuss the different mechanism which lead to the emergence of BF surfaces (i.e., surfaces of zero-modes in the energy spectrum of the Bogoliubov quasiparticles) in single and multiband superconductors. We demonstrate i) how interband pairing which spontaneously breaks time-reversal symmetry generates topological protected BF surfaces in centrosymmetric superconductors and ii) what the conditions for the emergence of BF surfaces in non-centrosymmetric superconductors are. Furthermore, we will investigate the stability of BFSs under a perturbation that breaks inversion symmetry. Recently, BFS were observed experimentally at the Al-InAs interface. Our model describing this experiment is presented and we show our predictions for the density-of-states and the heat capacity for this system.