Superfluid/ferromagnet/superfluid-junction and π-phase in a superfluid Fermi gas at finite temperatures

Abstract

We investigate the stability of -phase in a polarized superfluid Fermi gas ( ↑ > ↓ , where is the number of atoms in the hyperfine state described by pseudospin-). In our previous paper [T. Kashimura, S. Tsuchiya, and Y. Ohashi, Phys. Rev. A 82, 033617 (2010)], we showed that excess atoms (Δ = ↑ − ↓ ) localized around a potential barrier embedded in the system induces the -phase at = 0, where the phase of superfluid order parameter differ by across the junction. In this paper, we extend our previous work to include temperature effects within the mean-field theory. We show that the -phase is stable even at finite temperatures, although transition from the -phase to 0-phase eventually occurs at a certain temperature. Our results indicate that the -phase is experimentally accessible in cold Fermi gases.