Formation of magnetic impurities and pair-breaking effect in a superfluid Fermi gas

Journal Article · Wed Jun 15 04:00:00 EDT 2011 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.83.063611· OSTI ID:21550156

Ohashi, Y ^[1]

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1. Faculty of Science and Technology, Keio University, Hiyoshi, Yokohama, 223-8522 (Japan)

We theoretically investigate the introduction of magnetic impurities into a superfluid Fermi gas. In the presence of a population imbalance (N{sub {up_arrow}}>N{sub {down_arrow}}, where N{sub {sigma}} is the number of Fermi atoms with pseudospin {sigma}={up_arrow},{down_arrow}), we show that nonmagnetic potential scatterers embedded in the system are magnetized in the sense that some of the excess spin-{up_arrow} 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.

• OSTI ID: 21550156
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 6 Vol. 83; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANGULAR MOMENTUM
ATOMS
CRYSTAL MODELS
DIMENSIONLESS NUMBERS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ENERGY LEVELS
EXCITED STATES
FERMI GAS
HUBBARD MODEL
IMPURITIES
MAGNETISM
MATHEMATICAL MODELS
MEAN-FIELD THEORY
ORDER PARAMETERS
OSCILLATION MODES
PARTICLE PROPERTIES
PHYSICAL PROPERTIES
SINGLE-PARTICLE MODES
SPIN
SUPERCONDUCTIVITY
SUPERFLUIDITY