  We theoretically investigate a possible idea to introduce magnetic impurities
to a superfluid Fermi gas. In the presence of population imbalance
($N_\uparrow>N_\downarrow$, where $N_\sigma$ is the number of Fermi atoms with
pseudospin $\sigma=\uparrow,\downarrow$), we show that nonmagnetic potential
scatterers embedded in the system are magnetized in the sense that some of
excess $\uparrow$-spin atoms are localized around them. They destroy the
superfluid order parameter around them, as in the case of 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 simply manner, we treat an attractive Fermi
Hubbard model within the mean-field theory at T=0. We self-consistently
determine superfluid properties around a nonmagnetic impurity, such as the
superfluid order parameter, local population imbalance, as well as
single-particle density of states, in the presence of population imbalance.
Since the 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.
