13,781 research outputs found
Induced interaction in a spin-polarized Fermi gas
We study the effect of the induced interaction on the superfluidtransition
temperature of a spin-polarized Fermi gas. In the BCS limit, the polarization
is very small in the superfluid state, and the effect of the induced
interaction is almost the same as in the spin-balanced case. The temperature Tt
and the polarization Pt of the tricritical point are both reduced from
mean-field results by a factor about 2.22. This reduction is also significant
beyond the BCS limit. In the unitary limit, we find (Pt,Tt/TF)=(0.42,0.16), in
comparison with mean-field and experimental results.Comment: 6 pages, 2 figure
Rigidity of non-renormalizable Newton maps
Non-renormalizable Newton maps are rigid. More precisely, we prove that their
Julia set carries no invariant line fields and that the topological conjugacy
is equivalent to quasi-conformal conjugacy in this case
Collinear antiferromagnetic state in a two-dimensional Hubbard model at half filling
In a half-filled Hubbard model on a square lattice, the next-nearest-neighbor
hopping causes spin frustration, and the collinear antiferromagnetic (CAF)
state appears as the ground state with suitable parameters. We find that there
is a metal-insulator transition in the CAF state at a critical on-site
repulsion. When the repulsion is small, the CAF state is metallic, and a van
Hove singularity can be close to the Fermi surface, resulting in either a kink
or a discontinuity in the magnetic moment. When the on-site repulsion is large,
the CAF state is a Mott insulator. A first-order transition from the CAF phase
to the antiferromagnetic phase and a second-order phase transition from the CAF
phase to the paramagnetic phase are obtained in the phase diagram at zero
temperature.Comment: 5 pages, 5 figures, two column
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