287 research outputs found
Phase-sensitive tests of the pairing state symmetry in Sr2RuO4
Exotic superconducting properties of SrRuO have provided strong
support for an unconventional pairing symmetry. However, the extensive efforts
over the past decade have not yet unambiguously resolved the controversy about
the pairing symmetry in this material. While recent phase-sensitive experiments
using flux modulation in Josephson junctions consisting of SrRuO
and a conventional superconductor have been interpreted as conclusive evidence
for a chiral spin-triplet pairing, we propose here an alternative
interpretation. We show that an overlooked chiral spin-singlet pairing is also
compatible with the observed phase shifts in Josephson junctions and propose
further experiments which would distinguish it from its spin-triplet
counterpart.Comment: 4 pages, 1 figur
Determination of critical current density from arbitrary flux relaxation process
The current-carrying ability of a type-II superconductor is generally
represented by its critical current density. This can be determined by
measuring a flux relaxation process starting with a testing current density
that is greater than or equal to the critical value. Here we show that a flux
relaxation process starting with an intermediate current density can be
converted into a process starting with the critical current density by
introducing a virtual time interval. Therefore, one may calculate the critical
current density from the flux relaxation process starting with a current
density below the critical value. The exact solutions of the time dependence of
current density in the flux relaxation process were also discussed.Comment: 5 page
Josephson interferometer in a ring topology as a symmetry prove of Sr_2RuO_4
The Josephson effect is theoretically studied in two types of SQUIDs
consisting of wave superconductor and SrRuO. Results show various
response of the critical Josephson current to applied magnetic fields depending
on the type of SQUID and on the pairing symmetries. In the case of a
wave symmetry, the critical current in a corner SQUID becomes an asymmetric
function of magnetic fields near the critical temperatures. Our results well
explain a recent experimental finding [Nelson et. al, Science \textbf{306},
1151 (2004)]. We also discuss effects of chiral domains on the critical
current.Comment: 7 page
Calculation of gluon and four-quark condensates from the operator expansion
The magnitudes of gluon and four-quark condensates are found from the
analysis of vector mesons consisting of light quarks (the families of
and mesons) in the 3 loops approximation. The QCD model with infinite
number of vector mesons is used to describe the function . This model
describes well the experimental function . Polarization operators
calculated with this model coincide with the Wilson operator expansion at large
. The improved perturbative theory, such that the polarization operators
have correct analytical properties, is used. The result is . The electronic widths of and
are calculated.Comment: 18 pages, latex, changed content slightl
Probing interfacial pair breaking in tunnel junctions based on the first and the second harmonics of the Josephson current
It will be shown that a pronounced interfacial pair breaking can be
identified in Josephson tunnel junctions provided the first j_{1c} and the
second j_{2c} harmonics of the supercurrent, as well as the depairing current
in the bulk j_{dp}, are known. Namely, within the Ginzburg-Landau theory a
strong interfacial pair breaking results in the relation
j_{2c}j_{dp}>>j_{1c}^2, while in standard junctions, with negligibly small pair
breaking, the relation of opposite character takes place.Comment: 6 pages, published versio
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