Global superfluid phase diagram of a three-component fermion mixture with magnetic ordering

Abstract

We investigate a three-component fermion mixture in the presence of weak attractive interactions. We use a combination of the equation of motion and the Gaussian variational mean-field approaches, which both allow for simultaneous superfluid and magnetic ordering in an unbiased way, and capture the interplay between the two order parameters. This interplay significantly modifies the phase diagram, especially the superfluid-normal phase boundaries. In the close vicinity of the critical temperature and for small chemical potential imbalances, strong particle-hole symmetry breaking leads to a phase diagram similar to the one predicted by Cherng et al. [Phys. Rev. Lett. 99, 130406 (2007)], however, the overall phase diagram is markedly different: additional chemical potential-driven first- and second-order transitions and triple points emerge as well as more exotic second-order multicritical points, and bicritical lines with $\text{O}(2,2)$ symmetry. We identify the terms which are necessary to capture this complex phase diagram in a Ginzburg-Landau approach, and determine the corresponding coefficients.