Chiral d-wave superconductor with nonzero center-of-mass pair momentum

TL;DR

This paper explores a hypothetical two-dimensional chiral d-wave superconductor with nonzero pair momentum, revealing nearly degenerate order parameters and the potential for a fully gapped chiral state due to time-reversal symmetry breaking.

Contribution

It introduces a novel superconducting state with large pair momentum and demonstrates how it can form a chiral d+id state through numerical solutions.

Findings

Identification of nearly degenerate $d_{x^2-y^2}$ and $d_{xy}$ order parameters.

Spontaneous breaking of time-reversal symmetry leads to a chiral $d+id$ state.

Potential realization of topologically nontrivial superconductivity.

Abstract

Hypothetical topologically nontrivial superconducting state of two-dimensional electron system is discussed in connection with the problem of pairing with large center-of-mass pair momentum under predominant repulsive screened Coulomb interaction. Direct numerical solution of the self-consistency equation exhibits two nearly degenerate order parameters which can be formally referred to $d^{}_{x^2-y^2}$ and $d^{}_{xy}$ orbital symmetry. Spontaneous breaking of the time-reversal symmetry can mix these states and form fully gapped chiral $d+id$ superconducting state.