145,658 research outputs found
Structure of the breakpoint region in CVC of the intrinsic Josephson junctions
A fine structure of the breakpoint region in the current-voltage
characteristics of the coupled intrinsic Josephson junctions in the layered
superconductors is found. We establish a correspondence between the features in
the current-voltage characteristics and the character of the charge
oscillations in superconducting layers in the stack and explain the origin of
the breakpoint region structure.Comment: 5 pages, 5 figures. Accepted for Phys.Rev.
Temporary cooling of quasiparticles and delay in voltage response of superconducting bridges after abrupt switching on the supercritical current
We revisit the problem of the dynamic response of a superconducting bridge
after abruptly switching on the supercritical current . In contrast to
previous theoretical works we take into account spatial gradients and use both
the local temperature approach and the kinetic equation for the distribution
function of quasiparticles. In both models the finite delay time in the
voltage response is connected with temporary cooling of quasiparticles due to
the suppression of the superconducitng order parameter by current. We find that
has different values and different temperature dependencies in the
considered models. In turns out that the presence of even small inhomogeneities
in the bridge or of bulk leads/contacts at the ends of the {\it homogenous}
bridge favors a local suppression of the superconducting order parameter
during the dynamic response. It results in a decrease of the delay
time, in comparison with the spatially uniform model, due to the diffusion of
nonequilibrium quasiparticles from the region with locally suppressed
. In case the current distribution is spatially nonuniform across the
bridge the delay time is mainly connected with the time needed for the
nucleation of the first vortex at the position where the current density is
maximal (at and for not very wide films). We also find that a short
alternating current pulse (sinusoid like) with zero time-average may result in
a nonzero time-averaged voltage response where its sign depends on the phase of
the ac current.Comment: 13 pages, 11 figure
Multiphoton detachment from negative ions: new theory vs experiment
In this paper we compare the results of our adiabatic theory (Gribakin and
Kuchiev, Phys. Rev. A, accepted for publication) with other theoretical and
experimental results, mostly for halogen negative ions. The theory is based on
the Keldysh approach. It shows that the multiphoton detachment rates and the
corresponding n-photon detachment cross sections depend only on the asymptotic
behaviour of the bound state radial wave function. The dependence on the
exponent is very strong. This is the main reason for the disagreement with some
previous calculations, which employed bound state wave functions with incorrect
asymptotic forms. In a number of cases our theoretical results produces best
agreement with absolute and relative experimental data.Comment: 9 pages, Latex, IOP style, and 3 figures fig1.ps, fig2.ps, fig3.ps,
submitted to J. Phys.
Shapiro and parametric resonances in coupled Josephson junctions
The effect of microwave irradiation on the phase dynamics of intrinsic
Josephson junctions in high temperature superconductors is investigated. We
compare the current-voltage characteristics for a stack of coupled Josephson
junctions under external irradiation calculated in the framework of CCJJ and
CCJJ+DC models.Comment: 4 pages, Manuscript for Dubna-Nano 2012, submitted for Journal of
Physics:Conference Serie
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