Rashba versus Kohn-Luttinger: Evolution of p-wave superconductivity in magnetized two-dimensional Fermi gas subject to spin-orbit interaction

TL;DR

This paper investigates how Rashba spin-orbit coupling affects p-wave superconductivity in a magnetized 2D Fermi gas, revealing topological and nodal pairing states depending on magnetic field orientation.

Contribution

It demonstrates the evolution of superconducting pairing symmetry under spin-orbit interaction and magnetic field orientation, highlighting the emergence of topological and nodal states.

Findings

Only the larger Fermi surface becomes superconducting.

Out-of-plane magnetic field induces a topological p+ip state.

In-plane magnetic field leads to nodal pairing with finite momentum.

Abstract

We study how the Rashba spin-orbit interaction influences unconventional superconductivity in a two dimensional electron gas partially spin-polarized by a magnetic field. Somewhat surprisingly, we find that for all field orientations, only the larger Fermi surface is superconducting. When the magnetic field is oriented out-of-plane the system realizes a topological $p+ip$ pairing state. When the field is rotated in-plane the order parameter develops nodes along the field direction and finite center-of-mass-momentum pairing is realized. We demonstrate that the pairing symmetry of the system can be easily probed experimentally due to the dependence of various thermodynamic quantities on the magnetic field geometry, and calculate the electronic specific heat as an example.