900 research outputs found
Itinerant ferromagnetism in 1D two-component Fermi gases
We study a one-dimensional two-component atomic Fermi gas with an infinite
intercomponent contact repulsion. It is found that adding an attractive
resonant odd-wave interaction breaking the rotational symmetry one can make the
ground state ferromagnetic. A promising system for the observation of this
itinerant ferromagnetic state is a 1D gas of K atoms, where 3D -wave
and -wave Feshbach resonances are very close to each other and the 1D
confinement significantly reduces the inelastic decay.Comment: 5 pages, 2 figures, with 6 pages supplemental materia
Dynamical Properties of Multi-Armed Global Spirals in Rayleigh-Benard Convection
Explicit formulas for the rotation frequency and the long-wavenumber
diffusion coefficients of global spirals with arms in Rayleigh-Benard
convection are obtained. Global spirals and parallel rolls share exactly the
same Eckhaus, zigzag and skewed-varicose instability boundaries. Global spirals
seem not to have a characteristic frequency or a typical size ,
but their product is a constant under given experimental
conditions. The ratio of the radii of any two dislocations (,
) inside a multi-armed spiral is also predicted to be constant. Some of
these results have been tested by our numerical work.Comment: To appear in Phys. Rev. E as Rapid Communication
Hole Doping Dependence of the Coherence Length in Thin Films
By measuring the field and temperature dependence of magnetization on
systematically doped thin films, the critical current
density and the collective pinning energy are determined in
single vortex creep regime. Together with the published data of superfluid
density, condensation energy and anisotropy, for the first time we derive the
doping dependence of the coherence length or vortex core size in wide doping
regime directly from the low temperature data. It is found that the coherence
length drops in the underdoped region and increases in the overdoped side with
the increase of hole concentration. The result in underdoped region clearly
deviates from what expected by the pre-formed pairing model if one simply
associates the pseudogap with the upper-critical field.Comment: 4 pages, 4 figure
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