Superfluid/ferromagnet/superfluid junction and $\pi$-phase in a superfluid Fermi gas

Abstract

We investigate the possibility of superfluid/ferromagnet/superfluid (SFS)-junction in a superfluid Fermi gas. To examine this possibility in a simple manner, we consider an attractive Hubbard model at $T=0$ within the mean-field theory. When a potential barrier is embedded in a superfluid Fermi gas with population imbalance ($N_{\uparrow }>N_{\downarrow }$, where $N_{\sigma }$ is the number of atoms with pseudospin $\sigma =\uparrow ,\downarrow$), this barrier is shown to be {\it magnetized} in the sense that excess $\uparrow$-spin atoms are localized around it. The resulting superfluid Fermi gas is spatially divided into two by this {\it ferromagnet}, so that one obtains a junction similar to the superconductor/ferromagnet/superconductor-junction discussed in superconductivity. Indeed, we show that the so-called $\pi$-phase, which is a typical phenomenon in the SFS-junction, is realized, where the superfluid order parameter changes its sign across the junction. Our results would be useful for the study of magnetic effects on fermion superfluidity using an ultracold Fermi gas.

22 pages, 14 figures

References in corpus (15)

• Many-Body Physics with Ultracold Gases
• Ultracold atomic gases in optical lattices: mimicking condensed matter physics and beyond
• Theory of ultracold Fermi gases
• Scanning tunneling spectroscopy of high-temperature superconductors
• Crossover from a molecular Bose-Einstein condensate to a degenerate Fermi gas
• Using photoemission spectroscopy to probe a strongly interacting Fermi gas
• Evidence for Superfluidity of Ultracold Fermions in an Optical Lattice
• Observation of pseudogap behavior in a strongly interacting Fermi gas
• Critical velocity for superfluid flow across the BEC-BCS crossover
• Single-particle properties and pseudogap effects in the BCS-BEC crossover regime of an ultracold Fermi gas above Tc
• Surface Tension in Unitary Fermi Gases with Population Imbalance
• Pseudo-gap pairing in ultracold Fermi atoms
• Spectral signatures of the Fulde-Ferrell-Larkin-Ovchinnikov order parameter in one-dimensional optical lattices
• Realization and Detection of Fulde-Ferrell-Larkin-Ovchinnikov Superfluid Phases in Trapped Atomic Fermion Systems
• Imbalanced Superfluid Phase of a Trapped Fermi Gas in the BCS-BEC Crossover Regime

Cited by in corpus (3)

• Transport of Spin and Mass at Normal-Superfluid Interfaces in the Unitary Fermi Gas
• $\pi$-junction and spontaneous current state in a superfluid Fermi gas
• Phase tunable Josephson junction and spontaneous mass current in a spin-orbit coupled Fermi superfluid