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TT: Fachverband Tiefe Temperaturen
TT 53: Topology: Majorana Physics
TT 53.8: Vortrag
Donnerstag, 19. März 2020, 11:30–11:45, HSZ 103
Interacting Majorana modes at surfaces of noncentrosymmetric superconductors — •Janna Elisabeth Rückert, Gergö Roósz, and Carsten Timm — Institute of Theoretical Physics, Technische Universität Dresden, 01062 Dresden, Germany
Noncentrosymmetric superconductors with line nodes are expected to possess topologically protected flat zero-energy bands of surface states, which can be described as Majorana modes. We investigate their fate if residual interactions beyond BCS theory are included. For a minimal square-lattice model with a plaquette interaction, we find string-like integrals of motion that form Clifford algebras and lead to exact degeneracies. By mapping the Majorana model onto two decoupled spin compass models we can further analyse the gap above the ground state. Moreover, we compare the topological properties of the interacting Majorana model to those of the toric-code model. The Majorana model has long-range entangled ground states that differ by Z2 fluxes through the system on a torus. We find that the ground states exhibit string condensation similar to the toric code but that the topological order is not robust.