Spin-polarized impurities in ultracold Fermi gas

Although the phase diagram for spin-polarized ultracold Fermi gas is incomplete, it is possible to create meta-stable excited states that harbor low polarization values. In this talk, I will discuss a particular exotic configuration in spin-imbalanced ultracold Fermi gas, dubbed ferron. The ferron results from the modulation of the pairing field in the presence of a chemical potential difference between the spin components. This mechanism is essentially similar to the one behind the Josephson-pi junction in superconductor-ferromagnet-superconductor junctions or the Fulde-Ferrel-Larkin-Ovchinnikov phase. During the talk, I will present the dynamic creation and stability of the impurity and its properties, such as its effective mass, critical velocity, and finite temperature effects.