Spinodal decomposition in polarised Fermi superfluids

TL;DR

This paper analyzes the phase separation dynamics in polarized Fermi superfluids, identifying the spinodal region and unstable modes, and discusses potential experimental observations of domain structures.

Contribution

It provides a mean-field analysis of spinodal decomposition in polarized Fermi superfluids, including phase diagram mapping and unstable mode spectrum.

Findings

Identified the spinodal region in polarization vs. interaction strength phase diagram.

Derived the spectrum of unstable modes during phase separation.

Discussed experimental conditions for observing domain structures.

Abstract

We discuss the dynamics of phase separation through the process of spinodal decomposition in a Fermi superfluid with population imbalance. We discuss this instability first in terms of a phenomenological Landau theory. Working within the mean-field description at zero temperature, we then find the spinodal region in the phase diagram of polarisation versus interaction strength, and the spectrum of unstable modes in this region. After a quench, the spinodal decomposition starts from the Sarma state, which is a minimum of the free energy with respect to the order parameter at fixed density and polarisation and a maximum at fixed chemical potentials. The possibility of observing non-trivial domain structures in current experiments with trapped atomic gases is discussed.