1,858 research outputs found
Topological Structure of a Vortex in Fulde-Ferrell-Larkin-Ovchinnikov State
We find theoretically that the vortex core in the
Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state is quite different from the
ordinary core by a simple topological reason. The intersection point of a
vortex and nodal plane of the FFLO state empties the excess spins. This leads
to observable consequences in the spatial structure of the spontaneous
magnetization. We analyze this topological structure based on the low lying
excitation spectrum by solving microscopic Bogoliubov-de Gennes equation to
clarify its physical origin.Comment: 4 pages, 4 figure
Generic Phase Diagram of Fermion Superfluids with Population Imbalance
It is shown by microscopic calculations for trapped imbalanced Fermi
superfluids that the gap function has always sign changes, i.e., the
Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state like, up to a critical imbalance
, beyond which normal state becomes stable, at temperature T=0. A phase
diagram is constructed in vs , where the BCS state without sign change
is stable only at . We reproduce the observed bimodality in the
density profile to identify its origin and evaluate as functions of
and the coupling strength. These dependencies match with the recent
experiments.Comment: 5 pages, 5 figures, replaced by the version to appear in PR
Direct Imaging of Spatially Modulated Superfluid Phases in Atomic Fermion Systems
It is proposed that the spatially modulated superfluid phase, or the
Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state could be observed in resonant
Fermion atomic condensates which are realized recently. We examine optimal
experimental setups to achieve it by solving Bogoliubov-de Gennes equation both
for idealized one-dimensional and realistic three-dimensional cases. The
spontaneous modulation of this superfluid is shown to be directly imaged as the
density profiles either by optical absorption or by Stern-Gerlach experiments.Comment: 4 pages, 3 figure
Asymmetric Fermi superfluid with different atomic species in a harmonic trap
We study the dilute fermion gas with pairing between two species and unequal
concentrations in a harmonic trap using the mean field theory and the local
density approximation. We found that the system can exhibit a superfluid shell
structure sandwiched by the normal fermions. This superfluid shell structure
occurs if the mass ratio is larger then certain critical value which increases
from the weak-coupling BCS region to the strong-coupling BEC side. In the
strong coupling BEC regime, the radii of superfluid phase are less sensitive to
the mass ratios and are similar to the case of pairing with equal masses.
However, the lighter leftover fermions are easier to mix with the superfluid
core than the heavier ones. A partially polarized superfluid can be found if
the majority fermions are lighter, whereas phase separation is still found if
they are heavier.Comment: 12 pages, 7 figure
Significance of blood glucose variability in the early phase for predicting survival in acutely ill patients with glucose intolerance
Larkin-Ovchinnikov-Fulde-Ferrell phase in the superconductor (TMTSF)2ClO4: Theory versus experiment
We consider a formation of the Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) phase
in a quasi-one-dimensional (Q1D) conductor in a magnetic field, parallel to its
conducting chains, where we take into account both the paramagnetic
spin-splitting and orbital destructive effects against superconductivity. We
show that, due to a relative weakness of the orbital effects in a Q1D case, the
LOFF phase appears in (TMTSF)ClO superconductor for real values of its
Q1D band parameters. We compare our theoretical calculations with the recent
experimental data by Y. Maeno's group [S. Yonezawa et al., Phys. Rev. Lett.
\textbf{100}, 117002 (2008)] and show that there is a good qualitative and
quantitative agreement between the theory and experimental data.Comment: 4 pages, 1 figur
Superexchange in Dilute Magnetic Dielectrics: Application to (Ti,Co)O_2
We extend the model of ferromagnetic superexchange in dilute magnetic
semiconductors to the ferromagnetically ordered highly insulating compounds
(dilute magnetic dielectrics). The intrinsic ferromagnetism without free
carriers is observed in oxygen-deficient films of anatase TiO_2 doped with
transition metal impurities in cation sublattice. We suppose that ferromagnetic
order arises due to superexchange between complexes [oxygen vacancies +
magnetic impurities], which are stabilized by charge transfer from vacancies to
impurities. The Hund rule controls the superexchange via empty vacancy related
levels so that it becomes possible only for the parallel orientation of
impurity magnetic moments. The percolation threshold for magnetic ordering is
determined by the radius of vacancy levels, but the exchange mechanism does not
require free carriers. The crucial role of the non-stoichiometry in formation
of the ferromagnetism makes the Curie temperatures extremely sensitive to the
methods of sample preparation.Comment: 18 pages, 2 figure
Investigation of the blood glucose target for mortality reduction by means of bedside-type artificial pancreas
Ultracold + collisions in a magnetic field: on the role of the potential energy surface
The collision dynamics of in
the presence of a magnetic field is studied within the close-coupling formalism
in the range between 10 nK and 50 mK. A recent global {\em ab initio} potential
energy surface (PES) is employed and its effect on the dynamics is analyzed and
compared with previous calculations where an experimentally derived PES was
used [New J. Phys {\bf 11}, 055021 (2009)]. In contrast to the results using
the older PES, magnetic field dependence of the low-field-seeking state in the
ultracold regime is characterized by quite a large background scattering
length, , and, in addition, cross sections exhibit broad and pronounced
Feshbach resonances. The marked resonance structure is somewhat surprising
considering the influence of inelastic scattering, but it can be explained by
resorting to the analytical van der Waals theory, where the short range
amplitude of the entrance channel wave function is enhanced by the large
. This strong sensitivity to the short range of the {\em ab initio} PES
persists up to relatively high energies (10 mK). After this study and despite
quantitative predictions are very difficult, it can be concluded that the ratio
between elastic and spin relaxation scattering is generally small, except for
magnetic fields which are either low or close to an asymmetric Fano-type
resonance. Some general trends found here, such as a large density of
quasibound states and a propensity towards large scattering lengths, could be
also characteristic of other anisotropic molecule-molecule systems.Comment: 24 pages, 8 figure
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