Superconductivity of mixed parity and frequency in an anisotropic spin-orbit coupling

TL;DR

This paper explores how anisotropic spin-orbit coupling and Hubbard interactions influence superconducting phases, revealing mixed-parity gaps and frequency admixtures in noncentrosymmetric quantum wells.

Contribution

It provides a detailed analysis of mixed-parity and frequency superconductivity induced by anisotropic spin-orbit coupling and ferromagnetic exchange fields in quantum wells.

Findings

Broken inversion symmetry leads to mixed-parity superconducting gaps.

Hubbard interactions affect the symmetry of the superconducting order.

Ferromagnet exchange fields induce even- and odd-frequency admixtures.

Abstract

We illuminate the superconducting phases in [001]-grown-noncentrosymmetric quantum wells with an anisotropic spin-orbit coupling in the presence of on-site Hubbard interaction. Within the random phase approximation, we investigate the spin-fluctuation-mediated pairing in the presence of Rashba/Dresselhaus antisymmetric spin-orbit couplings. Although the existence of spatial inversion symmetry desires a dominant d-wave pairing for all filling levels, a broken inversion symmetry generates antisymmetric spin-orbit coupling and mixes the even- and odd-parity in the superconducting gap. We study the symmetry of the mixed-parity gap for various strengths of Hubbard interaction. Besides, we consider a superconductor-ferromagnet junction to survey the modifications of superconducting order parameters and observe an admixture of even- and odd-frequencies due to the ferromagnet exchange field.