Superconductivity near Pomeranchuk instabilities in the spin channel

TL;DR

This paper investigates how superconductivity interacts with Pomeranchuk instabilities in the spin channel, revealing a phase diagram with first-order transitions between p-wave and s-wave superconducting phases, and the potential for metastable modulated phases.

Contribution

It provides a mean-field analysis of the competition between spin-channel Pomeranchuk instabilities and superconductivity, highlighting the suppression of instabilities and the emergence of distinct superconducting phases.

Findings

Superconducting gap suppresses Pomeranchuk instability phase space.

First-order transition between p-wave and s-wave superconducting phases.

Metastable modulated superconducting phase in strong coupling regime.

Abstract

We study the competition between a Pomeranchuk instability in the spin channel with angular momentum $\ell=1$ and an attractive interaction, favoring Cooper-pair formation. We found that the superconducting gap strongly suppresses the phase space for the Pomeranchuk instability. We computed a mean-field phase diagram displaying a first order transition between two superconductor phases with different symmetries: p-wave (with spontaneously generated spin-orbit interaction) and s-wave for greater values of the coupling constant. Moreover, we have looked for a possible modulated superconducting phase. We have found that this phase appears only as a meta-stable state in the strong coupling regime.