264 research outputs found
Dynamic scaling for 2D superconductors, Josephson junction arrays and superfluids
The value of the dynamic critical exponent is studied for two-dimensional
superconducting, superfluid, and Josephson Junction array systems in zero
magnetic field via the Fisher-Fisher-Huse dynamic scaling. We find
, a relatively large value indicative of non-diffusive
dynamics. Universality of the scaling function is tested and confirmed for the
thinnest samples. We discuss the validity of the dynamic scaling analysis as
well as the previous studies of the Kosterlitz-Thouless-Berezinskii transition
in these systems, the results of which seem to be consistent with simple
diffusion (). Further studies are discussed and encouraged.Comment: 19 pages in two-column RevTex, 8 embedded EPS figure
Tunnelling of topological line defects in strongly coupled superfluids
The geometric theory of vortex tunnelling in superfluid liquids is developed.
Geometry rules the tunnelling process in the approximation of an incompressible
superfluid, which yields the identity of phase and configuration space in the
vortex collective co-ordinate. To exemplify the implications of this approach
to tunnelling, we solve explicitly for the two-dimensional motion of a point
vortex in the presence of an ellipse, showing that the hydrodynamic collective
co-ordinate description limits the constant energy paths allowed for the vortex
in configuration space. We outline the experimental procedure used in helium II
to observe tunnelling events, and compare the conclusions we draw to the
experimental results obtained so far. Tunnelling in Fermi superfluids is
discussed, where it is assumed that the low energy quasiparticle excitations
localised in the vortex core govern the vortex dynamical equations. The
tunnelling process can be dominated by Hall or dissipative terms, respectively
be under the influence of both, with a possible realization of this last
intermediate case in unconventional, high-temperature superconductors.Comment: 51 pages, 15 figures, uses Ann. Phys. (Leipzig) style file; forms
part of author's dissertation, available at
http://xxx.lanl.gov/abs/cond-mat/9909166v
Superconductors are topologically ordered
We revisit a venerable question: what is the nature of the ordering in a
superconductor? We find that the answer is properly that the superconducting
state exhibits topological order in the sense of Wen, i.e. that while it lacks
a local order parameter, it is sensitive to the global topology of the
underlying manifold and exhibits an associated fractionalization of quantum
numbers. We show that this perspective unifies a number of previous
observations on superconductors and their low lying excitations and that this
complex can be elegantly summarized in a purely topological action of the
``'' type and its elementary quantization. On manifolds with boundaries,
the action correctly predicts non-chiral edge states, gapped in general,
but crucial for fractionalization and establishing the ground state degeneracy.
In all of this the role of the physical electromagnetic fields is central. We
also observe that the action describes the topological order in several
other physically distinct systems thus providing an example of topological
universality
Non-equilibrium thermodynamics analysis of rotating counterflow superfluid turbulence
In two previous papers two evolution equations for the vortex line density
, proposed by Vinen, were generalized to rotating superfluid turbulence and
compared with each other. Here, the already generalized alternative Vinen
equation is extended to the case in which counterflow and rotation are not
collinear. Then, the obtained equation is considered from the viewpoint of
non-equilibrium thermodynamics. According with this formalism, the
compatibility between this evolution equation for and that one for the
velocity of the superfluid component is studied. The compatibility condition
requires the presence of a new term dependent on the anisotropy of the tangle,
which indicates how the friction force depends on the rotation rate.Comment: 18 pages, 3 figure
Electrodynamics of Abrikosov vortices: the Field Theoretical Formulation
Electrodynamic phenomena related to vortices in superconductors have been
studied since their prediction by Abrikosov, and seem to hold no fundamental
mysteries. However, most of the effects are treated separately, with no guiding
principle. We demonstrate that the relativistic vortex worldsheet in spacetime
is the object that naturally conveys all electric and magnetic information, for
which we obtain simple and concise equations. Breaking Lorentz invariance leads
to down-to-earth Abrikosov vortices, and special limits of these equations
include for instance dynamic Meissner screening and the AC Josephson relation.
On a deeper level, we explore the electrodynamics of two-form sources in the
absence of electric monopoles, in which the electromagnetic field strength
itself acquires the characteristics of a gauge field. This novel framework
leaves room for unexpected surprises.Comment: LaTeX, 23 pages, 5 figure
Ginzburg-Landau vortices, Coulomb Gases, and Renormalized Energies
This is a review about a series of results on vortices in the Ginzburg-Landau
model of superconductivity on the one hand, and point patterns in Coulomb gases
on the other hand, as well as the connections between the two topics.Comment: review paper, submitted to J. Stat. Phy
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