14,330 research outputs found
Optical Feshbach resonances of Alkaline-Earth atoms in a 1D or 2D optical lattice
Motivated by a recent experiment by Zelevinsky et al. [Phys. Rev. Lett. 96,
203201], we present the theory for photoassociation and optical Feshbach
resonances of atoms confined in a tight one-dimensional (1D) or two-dimensional
(2D) optical lattice. In the case of an alkaline-earth intercombination
resonance, the narrow natural width of the line makes it possible to observe
clear manifestations of the dimensionality, as well as some sensitivity to the
scattering length of the atoms. Among possible applications, a 2D lattice may
be used to increase the spectroscopic resolution by about one order of
magnitude. Furthermore, a 1D lattice induces a shift which provides a new way
of determining the strength of a resonance by spectroscopic measurements.Comment: 12 pages, 4 figures. Typos were corrected and a connection was made
to the fermionization of boson
Frequency-dependent effective permeability tensor of unsaturated polycrystalline ferrites
Frequency-dependent permeability tensor for unsaturated polycrystalline
ferrites is derived through an effective medium approximation that combines
both domain-wall motion and rotation of domains in a single consistent
scattering framework. Thus derived permeability tensor is averaged on a
distribution function of the free energy that encodes paramagnetic states for
anhysteretic loops. The initial permeability is computed and frequency spectra
are given by varying macroscopic remanent field.Comment: 24 pages, 3 figure
Hamiltonian Hopf bifurcation with symmetry
In this paper we study the appearance of branches of relative periodic orbits
in Hamiltonian Hopf bifurcation processes in the presence of compact symmetry
groups that do not generically exist in the dissipative framework. The
theoretical study is illustrated with several examples.Comment: 35 pages, 3 figure
Modeling Magnetic Anisotropy of Single Chain Magnets in Regime
Single molecule magnets (SMMs) with single-ion anisotropies ,
comparable to exchange interactions J, between spins have recently been
synthesized. In this paper, we provide theoretical insights into the magnetism
of such systems. We study spin chains with site spins, s=1, 3/2 and 2 and
on-site anisotropy comparable to the exchange constants between the
spins. We find that large leads to crossing of the states with
different values in the same spin manifold of the limit.
For very large 's we also find that the states of the higher
energy spin states descend below the states of the ground state spin
manifold. Total spin in this limit is no longer conserved and describing the
molecular anisotropy by the constants and is not possible. However,
the total spin of the low-lying large states is very nearly an integer
and using this spin value it is possible to construct an effective spin
Hamiltonian and compute the molecular magnetic anisotropy constants and
. We report effect of finite sizes, rotations of site anisotropies and
chain dimerization on the effective anisotropy of the spin chains
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