7,230 research outputs found
Fulde-Ferrell-Larkin-Ovchinnikov state in d-wave superconductors
The Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state can be found in layered
d-wave superconductors such as high cuprates and -(ET) salts
in a planar magnetic field. We show the superconducting order parameter forms
two dimensional crystalline lattice in the FFLO state for d-wave
superconductors. Also the quasiparticle density of states and the
thermodynamics of FFLO state are constructed. Therefore STM or NMR will provide
a definitive test for the existence of the FFLO state.Comment: 5 pages including 2 figure
Thermal conductivity in superconducting borocarbides LuNi2B2C and YNi2B2C
We have recently proposed the s+g wave model for superconducting
borocarbides. In spite of a substantial s-wave component, this order parameter
exhibits the H^1/2 dependent specific heat and a thermal conductivity linear in
H in the vortex state. This is characteristic for nodal superconductors when T,
\Gamma << \Delta where \Gamma is the quasiparticle scattering rate and \Delta
the maximum superconducting gap. Here we investigate the thermal conductivity
parallel to the c- and a- axis in a magnetic field tilted by \theta from the c-
axis and rotating within the a-b plane.Comment: SCES 2002 conference contribution, 2 pages and 2 figure
Thermal Conductivity in Vortex State of Nodal Superconductors
How to determine the symmetry of the superconducting order parameter is one
of the important issues in novel superconductors, which include charge
conjugated organic superconductors. We have proposed that the angular
dependence of the thermal conductivity in a planar magnetic field provides a
new window to look at the symmetry of the order parameter. After a brief
summary of the quasiclassical approach we describe how the symmetry of the
superconducting order parameter in SrRuO, CeCoIn and
-(ET)Cu(NCS) is determined. Also in some of experiments the
phononic thermal conductivity plays the crucial role.Comment: 5 pages, 3 figures. to be published in Synthetic Metal
Nonlinear response and scaling law in the vortex state of d-wave superconductors
We study the field dependence of the quasi-particle density of states, the
thermodynamics and the transport properties in the vortex state of d-wave
superconductors when a magnetic field is applied perpendicular to the
conducting plane, specially for the low field and the low temperature compared
to the upper critical field and transition temperature, respectively, and . Both the superfluid density and the spin
susceptibility exhibit the characteristic -field dependence, while
the nuclear spin lattice relaxation rate T and the thermal
conductivity are linear in field . With increasing temperature, these
quantities exhibit the scaling behavior in . The present theory
applies to 2D -wave superconductor as well; a possible candidate of the
superconductivity in SrRuO.Comment: 11 pages, 4 figure
Low-lying excitations around a single vortex in a d-wave superconductor
A full quantum-mechanical treatment of the Bogoliubov-de Gennes equation for
a single vortex in a d-wave superconductor is presented. First, we find
low-energy states extended in four diagonal directions, which have no
counterpart in a vortex of s-wave superconductors. The four-fold symmetry is
due to 'quantum effect', which is enhanced when is small. Second,
for , a peak with a large energy gap is
found in the density of states, which is due to the formation of the lowest
bound states.Comment: 7pages, Revte
Out of plane optical conductivity in d-wave superconductors
We study theoretically the out of plane optical conductivity of d-wave
superconductors in the presence of impurities at T=0K. Unlike the usual
approach, we assume that the interlayer quasi-particle transport is due to
coherent tunneling. The present model describes the T^2 dependence of the out
of plane superfluid density observed in YBCO and Tl2201 for example. In the
optical conductivity there is no Drude peak in agreement with experiment, and
the interlayer Josephson tunneling is also assured in this model. In the
unitary limit we predict a step like behaviour around omega=Delta in both the
real and imaginary part of the optical conductivity.Comment: 7 pages, 7 figure
Critical Current of the Spin-Triplet Superconducting Phase in SrRuO
There have been two different proposals for the spin-triplet order parameter
of the superconducting phase in SrRuO; an -wave order parameter and
the multigap model where some of the bands have the line node. In an effort to
propose an experiment that can distinguish two cases, we study the behavior of
the supercurrent and compute the critical current for these order parameters
when the sample is a thin film with the thickness where is
the coherence length. It is found that the supercurrent behaves very
differently in two models. This will serve as a sharp test for the
identification of the correct order parameter.Comment: 4 pages, 1 figur
Scaling Relations in the Vortex State of Nodal Superconductors
In contrast to multigap superconductors (e.g. MgB), the low-temperature
properties of nodal superconductors are dominated by nodal excitations. Here we
extend for a variety of nodal superocnductors the earlier work by Simon and Lee
and K\"ubert and Hirschfeld. The scaling relations seen in the thermodynamics
and the thermal conductivity will provide an unequivocal test of nodal
superconductivity.Comment: 9 pages, 3 figure
Possible f-wave superconductivity in SrRuO?
Until recently it has been believed that the superconductivity in
SrRuO is described by p-wave pairing. However, both the recent specific
heat and the magnetic penetration depth measurements on the purest single
crystals of SrRuO appear to be explained more consistently in terms of
f-wave superconductivity. In order to further this hypothesis, we study
theoretically the thermodynamics and thermal conductivity of f-wave
superconductors in a planar magnetic field. We find the simple expressions for
these quantities when and , which should be
readily accessible experimentally.Comment: 6 pages, 2 figure
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