6,715 research outputs found
Josephson Current between Triplet and Singlet Superconductors
The Josephson effect between triplet and singlet superconductors is studied.
Josephson current can flow between triplet and singlet superconductors due to
the spin-orbit coupling in the spin-triplet superconductor but it is finite
only when triplet superconductor has , where and
are the perpendicular components of orbital angular momentum and spin angular
momentum of the triplet Cooper pairs, respectively. The recently observed
temperature and orientational dependence of the critical current through a
Josephson junction between UPt and Nb is investigated by considering a
non-unitary triplet state.Comment: 4 pages, no figure
Phase diagram of asymmetric Fermi gas across Feshbach resonance
We study the phase diagram of the dilute two-component Fermi gas at zero
temperature as a function of the polarization and coupling strength. We map out
the detailed phase separations between superfluid and normal states near the
Feshbach resonance. We show that there are three different coexistence of
superfluid and normal phases corresponding to phase separated states between:
(I) the partially polarized superfluid and the fully polarized normal phases,
(II) the unpolarized superfluid and the fully polarized normal phases and (III)
the unpolarized superfluid and the partially polarized normal phases from
strong-coupling BEC side to weak-coupling BCS side. For pairing between two
species, we found this phase separation regime gets wider and moves toward the
BEC side for the majority species are heavier but shifts to BCS side and
becomes narrow if they are lighter.Comment: 4 pages, 3 figures. Submitted to LT25 on June 200
Thin Films of 3He -- Implications on the Identification of 3 He -A
Recently the identification of 3He-A with the axial state has been
questioned. It is suggested that the A-phase can actually be in the axiplanar
state. We point out in the present paper that experiments in a film geometry
may be useful to distinguish the above two possibilities. In particular a
second order phase transition between an axial and an axiplanar state would
occur as a function of thickness or temperature.Comment: 3 pages, no figures latex- revtex aps accepted by J. of Low
Temperature Physic
Resonant pairing between Fermions with unequal masses
We study the pairing between Fermions of different masses, especially at the
unitary limit. At equal populations, the thermodynamic properties are identical
with the equal mass case provided an appropriate rescaling is made. At unequal
populations, for sufficiently light majority species, the system does not phase
separate. For sufficiently heavy majority species, the phase separated normal
phase have a density larger than that of the superfluid. For atoms in harmonic
traps, the density profiles for unequal mass Fermions can be drastically
different from their equal-mass counterparts.Comment: 10 pages, 4 figure
Phase diagram of a dilute fermion gas with density imbalance
We map out the phase diagram of a dilute two-component atomic fermion gas
with unequal populations and masses under a Feshbach resonance. As in the case
of equal masses, no uniform phase is stable for an intermediate coupling
regime. For majority component heavier, the unstable region moves towards the
BEC side. When the coupling strength is increased from the normal phase, there
is an increased parameter space where the transition is into the FFLO state.
The converse is true if the majority is light.Comment: Proceeding for MS-HTSC VIII meeting, July 9-14 2006, Dresden; To
appear in Physica
Superfluid stability in BEC-BCS crossover
We consider a dilute atomic gas of two species of fermions with unequal
concentrations under a Feshbach resonance. We find that the system can have
distinct properties due to the unbound fermions. The uniform state is stable
only when either (a) beyond a critical coupling strength, where it is a gapless
superfluid, or (b) when the coupling strength is sufficiently weak, where it is
a normal Fermi gas mixture. Phase transition(s) must therefore occur when the
resonance is crossed.Comment: 4 pages, 4 figure
Magnetic Field Effect on the Supercurrent of an SNS junction
In this paper we study the effect of a Zeeman field on the supercurrent of a
mesoscopic SNS junction. It is shown that the supercurrent suppression is due
to a redistribution of current-carrying states in energy space. A dramatic
consequence is that (part of the) the suppressed supercurrent can be recovered
with a suitable non-equilibrium distribution of quasiparticles.Comment: 4 figures in postscrip
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