Impurity effects in a two-dimensional topological superconductor: A link of Tc-robustness with a topological number

Abstract

Impurity effects are probes for revealing an unconventional property in superconductivity. We study effects of non-magnetic impurities, in a 2D topological superconductor with s-wave pairing, the Rashba spin-orbit coupling, and the Zeeman term. Using a self-consistent T-matrix approach, we calculate a phenomenological formula for the Thouless-Kohmoto-Nightingale-Nijs (TKNN) invariant in interacting systems, as well as density of states, with different magnetic fields. This quantity weakly depends on the magnetic field, when a spectral gap opens, whereas this changes drastically, when in-gap states occurs. Furthermore, in the latter case, we find that the Anderson's theorem (robustness of s-wave superconductivity against non-magnetic impurities) breaks down. We discuss the origin, from the viewpoints of both unconventional superconductivity and the TKNN invariant.

6 pages, 6 figures, to be published in J. Phys. Soc. Jpn

References in corpus (4)

• Non-Abelian Topological Order in S-Wave Superfluids of Ultracold Fermionic Atoms
• Pressure induced Superconductivity in Topological Compound Bi2Te3
• Non-Abelian Topological Orders and Majorana Fermions in Spin-Singlet Superconductors
• Parity-Mixed Superconductivity in Locally Non-centrosymmetric System

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• Critical Temperature Enhancement of Topological Superconductors: A Dynamical Mean Field Study
• Orbital angular momentum in a nonchiral topological superconductor
• Impurity-induced resonant states in topological nodal-line semimetals
• Topological s-wave pairing superconductivity with spatial inhomogeneity: Mid-gap-state appearance and robustness of superconductivity
• Self-consistent study of topological superconductivity in two-dimensional quasicrystals
• Multi-band Eilenberger theory of superconductivity: Systematic low-energy projection
• Charge-impurity-induced Majorana fermions in topological superconductors