Diversified vortex phase diagram for a rotating trapped two-band Fermi gas in the BCS-BEC crossover

TL;DR

This paper maps the vortex phase diagram of a rotating two-band Fermi gas across the BCS-BEC crossover, revealing non-monotonic free energy behavior and novel interband interaction effects on vortex stability.

Contribution

It introduces a detailed vortex phase diagram for a two-band Fermi gas using finite-temperature effective field theory, highlighting new features due to interband interactions.

Findings

Resonant non-monotonic free energy dependence on temperature and rotation frequency.

Identification of stable integer and fractional vortex states.

Distinct vortex behavior in BCS and BEC regimes.

Abstract

We report the equilibrium vortex phase diagram of a rotating two-band Fermi gas confined to a cylindrically symmetric parabolic trapping potential, using the recently developed finite-temperature effective field theory [Phys. Rev. A $\bf{94}$, 023620 (2016)]. A non-monotonic resonant dependence of the free energy as a function of the temperature and the rotation frequency is revealed for a two-band superfluid. We particularly focus on novel features that appear as a result of interband interactions and can be experimentally resolved. The resonant dependence of the free energy is directly manifested in vortex phase diagrams, where areas of stability for both integer and fractional vortex states are found. The study embraces the BCS-BEC crossover regime and the entire temperature range below the critical temperature $T_{c}$. Significantly different behavior of vortex matter as a function of the interband coupling is revealed in the BCS and BEC regimes.