Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 73: Low-Dimensional Systems: Topological Order
TT 73.6: Vortrag
Donnerstag, 10. März 2016, 16:15–16:30, H19
Interaction-driven strong topology on the boundary of a weak topological superconductor — •Daniel Mendler1,2, Panagiotis Kotetes1,3, and Gerd Schön1,2 — 1Inst. für theo. Festkörperphysik, Karlsruhe Inst. of Technology — 2Inst. of Nanotechnology, Karlsruhe Inst. of Technology — 3Center for Quantum Devices, Niels Bohr Inst., U. of Copenhagen
We focus on a class of topological superconductors (TSCs) which exhibit a bulk energy gap and support Majorana flat bands (MFBs) on the surface. In contrast to previous proposals relying on strong TSCs with nodal bandstructure, here MFBs are solely protected by a weak topological invariant reflecting a global or local strong anisotropy. In the present case interactions play a dual role, on one hand driving the spontaneous symmetry breaking to an anisotropic superconducting phase and on the other, gapping out the arising MFBs yielding a strong topological phase on the boundary. The prototype system showing this kind of behavior is the nematic pz-superconductor, which supports surface MFBs. While the interactions stabilize the pz-SC phase in the bulk and induce the MFBs, suppressed bulk p-wave pairing terms occur on the surface, thus lifting the MFB-degeneracy. A similar situation can take place if the nematic features are only local, a scenario which is realizable in a heterostructure consisting of a conventional superconductor in proximity to a topological insulator surface with intrinsic magnetic order.