17 research outputs found
Superconducting thin rings with finite penetration depth
Recently Babaei Brojeny and Clem [Phys. Rev. B 68, 174514 (2003)] considered
superconducting thin-film rings in perpendicular magnetic fields in the ideal
Meissner state with negligibly small magnetic penetration depth and presented
useful analytical limiting expressions and numerical results for the
magnetic-field and sheet-current profiles, trapped magnetic flux,
self-inductance, magnetic moment, and focusing of magnetic flux into the hole
when no net current flows in the ring. The present paper generalizes all these
results to rings with arbitrary values of the two-dimensional effective
penetration depth \Lambda = \lambda^2 /d (\lambda is the London depth and d <
\lambda/2 the film thickness) using a straightforward matrix inversion method.
We also present results for the energy of a superconducting ring as a function
of the applied magnetic induction B_a and the quantum number N defining the
size of the fluxoid N \phi_0 trapped in the hole.Comment: with 19 figures, gives 11.5 page
Flux transitions in a superconducting ring
We perform a numeric study of the flux transitions in a superconducting ring
at fixed temperature, while the applied field is swept at an ideally slow rate.
The current around the ring and its free energy are evaluated. We partially
explain some of the known experimental features, and predict a considerably
large new feature: in the vicinity of a critical field, giant jumps are
expected
Symmetric and asymmetric states in a mesoscopic superconducting wire in the voltage-driven regime
The response of a mesoscopic homogeneous superconducting wire, connected with
bulk normal metal reservoirs, is theoretically investigated as function of the
applied voltage. The finite relaxation length of the nonequilibrium
quasiparticle distribution function is included where we assumed
that our wire is in the dirty limit. We found that {\it both} symmetric and
asymmetric states can exist which are characterized by a stationary symmetric
and asymmetric distribution of the order parameter with respect to the center
of the wire. Current voltage characteristics of the wire with length
being in the symmetric state show a pronounced S-behavior. The
asymmetric state may exist only for voltages larger than some critical value
and coexist with the symmetric state in a finite voltage interval. For wires
with the asymmetric state survives up to higher values of
the voltage than the symmetric one and may exist both in the voltage and the
current driven regimes. We propose an experiment to observe reversible
switching between those stationary symmetric and asymmetric states.Comment: 8 pages, 12 figure
Strong influence of nonlocal nonequilibrium effects on the dynamics of the order parameter in a phase-slip center: ring studies
The break-up of the vortex structure in a mesoscopic wire containing a constriction
Within the nonlinear Ginzburg-Landau theory, we study the
superconducting state in a mesoscopic wire containing a narrow
constriction in the presence of a uniform magnetic field directed
along the wire. If the narrow region is small enough so that no
vortices can penetrate through it, curved vortices are formed, i.e.
they enter at the top of the sample (the widest part) and exit
near the constriction. At high magnetic fields a giant vortex is
nucleated in the widest part of the wire which breaks up into a
smaller giant and/or individual vortices near the constriction