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TT: Fachverband Tiefe Temperaturen

TT 93: Superconductivity: (General) Theory

TT 93.1: Vortrag

Donnerstag, 3. April 2014, 16:30–16:45, HSZ 201

Symmetry-protected topological invariant and Majorana impurity states in time-reversal invariant superconductors — •Lukas Kimme¹, Timo Hyart², and Bernd Rosenow¹ — ¹Institut für Theoretische Physik, Universität Leipzig, D-04103 Leipzig, Germany — ²Instituut-Lorentz, Universiteit Leiden, Post Office Box 9506, 2300 RA Leiden, The Netherlands

We address the question of whether individual nonmagnetic impurities can induce zero-energy states in time reversal invariant superconductors, and define a class of symmetries which guarantee the existence of such Majorana states for a specific value of the impurity strength [1]. These symmetries allow the definition of a position space topological Z₂ invariant, which is related to the standard bulk topological Z₂ invariant. Our general results are applied to the time reversal invariant p-wave phase of the doped Kitaev-Heisenberg model [2], where we also demonstrate how a lattice of impurities drives a topologically trivial system into the non-trivial phase and even causes gapless topological superconductivity. Finally, signatures of impurity states in the spin-susceptibility are described.
L. Kimme, T. Hyart, and B. Rosenow, arXiv:1308.2496
T. Hyart, A. R. Wright, G. Khaliullin, and B. Rosenow, Phys. Rev. B 85, 140510(R) (2012).