Stability of Unconventional Superconductivity on Surfaces of Topological Insulators

TL;DR

This paper investigates the robustness of unconventional superconductivity on topological insulator surfaces, showing it remains stable against time-reversal symmetric impurities despite its anisotropic nature.

Contribution

It demonstrates that surface superconductivity with mixed s-wave and p-wave symmetry is resilient to TRS impurities using Abrikosov-Gor'kov theory.

Findings

Unconventional superconductivity on topological insulator surfaces is robust against TRS impurities.

Anisotropic, nodeless p-wave components can survive impurity effects.

Contrasts with traditional s-wave superconductivity's insensitivity to impurities.

Abstract

Superconductivity on the surface of topological insulators is known to be anisotropic and unconventional in that the symmetry is the mixture of s-wave and nodeless p-wave component. In contrast to Anderson's theorem for the insensitivity of the s-wave superconducting critical temperature to the nonmagnetic (time-reversal symmetric (TRS)) impurities, anisotropic superconductors including nodeless p-wave one are in general fragile even with small concentration of the TRS impurities. By employing the Abrikosov-Gor'kov theory, we clarify that this type of unconventional superconductivity emergent on the surface state of the strong topological insulators robustly survive against TRS impurities.