Superconductivity with two-fold symmetry in topological superconductor SrxBi2Se3

TL;DR

This paper provides experimental evidence of two-fold superconductivity in SrxBi2Se3, a topological superconductor, supporting the existence of unconventional pairing symmetry predicted by theory.

Contribution

The study demonstrates two-fold superconductivity in SrxBi2Se3 using resistivity measurements with a Corbino-like setup, confirming theoretical predictions of unconventional pairing symmetry.

Findings

Evidence of two-fold superconductivity in SrxBi2Se3

Maximum gap direction aligned with crystallographic axes

Supports theoretical prediction of unconventional pairing

Abstract

Topological superconductivity is the quantum condensate of paired electrons with an odd parity of the pairing function. One of the candidates is the triplet pairing superconductor derived from topological insulator Bi2Se3 by chemical doping. Theoretically it was predicted that a two-fold superconducting order parameter may exist in this kind of bulk topological superconductor. Earlier experiments by nuclear magnetic resonance and angle-resolved magnetocaloric measurements seem to support this picture. By using a Corbino-shape like electrode configuration, we measure the c-axis resistivity without the influence of the vortex motion and find clear evidence of two-fold superconductivity in the recently discovered topological superconductor SrxBi2Se3. The Laue diffraction measurements on these samples show that the maximum gap direction is either parallel or perpendicular to the main crystallographic axis.