2011/03/10 by Yoji Ohashi
Physics and Astronomy · #Atomic and Subatomic Physics Research #Cold Atom Physics and Bose-Einstein Condensates #Condensed matter physics #Electron #Fermi gas #Fermi liquid theory #Impurity #Magnetism #Order (exchange) #Physics #Physics of Superconductivity and Magnetism #Population #Quantum mechanics #Spin (aerodynamics) #Superconductivity #Superfluidity #cond-mat.other #cond-mat.supr-con
paper · pdf · doi:10.1103/physreva.83.063611
27 pages, 14 figures
arxiv created 2011/03/10 · openalex publication_date 2011/06/10 · arxiv updated 2015/05/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We theoretically investigate the introduction of magnetic impurities into a superfluid Fermi gas. In the presence of a population imbalance (N_\ensuremath\uparrow>N_\ensuremath\downarrow, where N_\ensuremathσ is the number of Fermi atoms with pseudospin \ensuremathσ=\ensuremath\uparrow,\ensuremath\downarrow), we show that nonmagnetic potential scatterers embedded in the system are magnetized in the sense that some of the excess spin-\ensuremath\uparrow atoms are localized around them. They destroy the superfluid order parameter around them, as in the case of the magnetic impurity effect discussed in the superconductivity literature. This pair-breaking effect naturally leads to localized excited states below the superfluid excitation gap. To confirm our idea in a simple manner, we consider an attractive Fermi-Hubbard model within the mean-field theory at T=0. We determine consistent superfluid properties around a nonmagnetic impurity, such as the superfluid order parameter, local population imbalance, as well as the single-particle density of states, in the presence of a population imbalance. Since competition between superconductivity and magnetism is one of the most fundamental problems in condensed-matter physics, our results would be useful for the study of this important issue in cold Fermi gases.