116 research outputs found
Nonconstant electronic density of states tunneling inversion for A15 superconductors: Nb3Sn
We re-examine the tunneling data on A15 superconductors by performing a
generalized McMillan-Rowell tunneling inversion that incorporates a nonconstant
electronic density of states obtained from band-structure calculations. For
Nb3Sn, we find that the fit to the experimental data can be slightly improved
by taking into account the sharp structure in the density of states, but it is
likely that such an analysis alone is not enough to completely explain the
superconducting tunneling characteristics of this material. Nevertheless, the
extracted Eliashberg function displays a number of features expected to be
present for the highest quality Nb3Sn samples.Comment: 11 pages, 11 figure
Study of the defect structures in irradiated Al- and NbC-single crystals by the channeling technique
Theory of tunneling spectroscopy in superconducting Sr2RuO4
A theory for tunneling spectroscopy in normal metal /insulator/triplet
superconductor junction is presented. We assume two kinds of non-unitary
triplet superconducting states which are the most promising states for
SrRuO. The calculated conductance spectra showzero-bias peaks as
well as gap structures. The existences of residual components in the spectra
reflect the non-unitary properties of superconducting states.Comment: 5pages, 4figures(included), to be published in Phys.Rev.B 56, (1997
Interplay between single-particle and two-particle tunneling in normal metal-d-wave superconductor junctions probed by shot noise
We discuss how life-time broadening of quasiparticle states influences
single- and two-particle current transport through zero-energy states at normal
metal/d-wave superconductor junctions. We distinguish between intrinsic
broadening (imaginary part of the energy), which couples the bound
states with the superconducting reservoir, and broadening due to leakage
through the junction barrier, which couples the bound states with the normal
metal reservoir. We show that shot noise is highly sensitive to the mechanism
of broadening, while the conductance is not. In the limit of small but finite
intrinsic broadening, compared to the junction transparency ,
, the low-voltage shot noise at zero frequency and zero
temperature becomes proportional to the magnitude of intrinsic
broadening ( is the maximum d-wave gap).Comment: 6 pages, 4 figures; presented at the SDP2001 conference in Toky
Resonant transport through midgap states in voltage-biased Josephson junctions of d-wave superconductors
We study theoretically the ac Josephson effect in voltage biased planar
junctions of d-wave superconductors. For some orientations of the
superconductors a current peak is found at finite voltage in the
current-voltage characteristics. We pick out the relevant physical processes
and write down an analytical formula for the current which clearly shows how
the midgap state acts as a resonance and produces the peak. We present a
possible explanation for the zero-bias conductance peak, recently found in
experiments on grain boundary junctions of high-temperature superconductors, in
terms of resonant transmission through midgap state of quasiparticles
undergoing multiple Andreev reflections. We note that within our framework the
zero-bias conductance peak appears in rather transparent Josephson junctions of
d-wave superconductors.Comment: 10 pages, 5 figures, Submitted to a special volume of "Superlattices
and Microstructures
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