1,377 research outputs found
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
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
Magnetic skyrmion lattices in heavy fermion superconductor UPt3
Topological analysis of nearly SO(3)_{spin} symmetric Ginzburg--Landau
theory, proposed for UPt by Machida et al, shows that there exists a new
class of solutions carrying two units of magnetic flux: the magnetic skyrmion.
These solutions do not have singular core like Abrikosov vortices and at low
magnetic fields they become lighter for strongly type II superconductors.
Magnetic skyrmions repel each other as at distances much larger then the
magnetic penetration depth , forming a relatively robust triangular
lattice. The magnetic induction near is found to increase as
. This behavior agrees well with experiments.Comment: 4 pages, 2 figures, 2 column format; v2:misprint in the title is
correcte
Theory of Ferromagnetic Superconductivity
It is argued that the pairing symmetry realized in a ferromagnetic
superconductor UGe must be a non-unitary triplet pairing. This particular
state is free from the Pauli limitation and can survive under a huge internal
molecular filed. To check our identification we examine its basic properties
and several experiments are proposed. In particular, the external field is used
to raise by controlling the internal spontaneous dipole field.Comment: 4 pages, no 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
Incommensurate Magnetism around Vortices and Impurities in High- Superconductors
By solving self-consistently an effective Hamiltonian including interactions
for both antiferromagnetic spin-density wave (SDW) and d-wave superconducting
(DSC) orderings, a comparison study is made for the local magnetic structure
around superconducting vortices and unitary impurities. To represent the
optimally doped regime of cuprates, the parameter values are chosen such that
the DSC is dominant while the SDW is vanishingly small. We show that when
vortices are introduced into the superconductor, an oscillating SDW is induced
around them. The oscillation period of the SDW is microscopically found,
consistent with experiments, to be eight lattice constants (). The
associated charge-density wave (CDW) oscillates with a period of one half
() of the SDW. In the case of unitary impurities, we find a SDW
modulation with identical periodicity, however without an associated CDW. We
propose neutron scattering experiments to test this prediction.Comment: 5 pages, 4 eps figures (color) included in the tex
Quantum Hall line junction with impurities as a multi-slit Luttinger liquid interferometer
We report on quantum interference between a pair of counterpropagating
quantum Hall edge states that are separated by a high quality tunnel barrier.
Observed Aharonov-Bohm oscillations are analyzed in terms of resonant tunneling
between coupled Luttinger liquids that creates bound electronic states between
pairs of tunnel centers that act like interference slits. We place a lower
bound in the range of 20-40 m for the phase coherence length and directly
confirm the extended phase coherence of quantum Hall edge states.Comment: 4 pages, 3 figures, 1 tabl
Lateral distribution of high energy hadrons and gamma ray in air shower cores observed with emulsion chambers
A high energy event of a bundle of electrons, gamma rays and hadronic gamma rays in an air shower core were observed. The bundles were detected with an emulsion chamber with thickness of 15 cm lead. This air shower is estimated to be initiated with a proton with energy around 10 to the 17th power to 10 to the 18th power eV at an altitude of around 100 gmc/2. Lateral distributions of the electromagnetic component with energy above 2 TeV and also the hadronic component of energy above 6 TeV of this air shower core were determined. Particles in the bundle are produced with process of the development of the nuclear cascade, the primary energy of each interaction in the cascade which produces these particles is unknown. To know the primary energy dependence of transverse momentum, the average products of energy and distance for various average energies of secondary particles are studied
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