5 research outputs found
Dynamics of d-wave Vortices: Angle-Dependent Nonlinear Hall Effect
We study the dynamics of vortices in d-wave superconductors using a
phenomenological time-dependent Ginzburg-Landau equation with mixing of s- and
d-wave components. We present numerical simulations under an external driving
current oriented with an angle with respect to the crystal axis,
calculating the vortex motion and induced electric fields for .
We find an intrinsic Hall effect for which depends as
, and increases non-linearly with .Comment: 11 pages, 3 figures, submitted to Phys. Rev. Let
Quasiclassical theory of superconductivity: a multiple interface geometry
The purpose of the paper is to suggest a new method which allows one to study
multiple coherent reflection/transmissions by partially transparent interfaces
(e.g. in multi-layer mesoscopic structures or grain boundaries in high-Tc's) in
the framework of the quasiclassical theory of superconductivity. It is argued
that typically the trajectory of the particle is a simply connected tree (no
loops) with knots, i.e. the points where interface scattering events occur and
ballistic pieces of the trajectory are mixed. A linear boundary condition for
the 2-component trajectory "wave function" which factorizes matrix (retarded)
Green's function, is formulated for an arbitrary interface, specular or
diffusive. To show the usage of the method, the current response to the vector
potential (the total superfluid density rho_s) of a SS' sandwich with the
different signs of the order parameter in S and S', is calculated. In this
model, a few percent of reflection by the SS' interface transforms the
paramagnetic response (rho_s < 0) created by the zero-energy Andreev bound
states near an ideal interface (see Fauchere et al. PRL, 82, 3336 (1999),
cond-mat/9901112), into the usual diamagnetic one (rho_s >0).Comment: Extended abstract submitted to "Electron Transport in Mesoscopic
Systems", Satellite conference to LT22, Goteborg, 12-15 August, 1999. 2 pages
Minor changes + the text height problem fixe
Quasiparticle spectra in the vicinity of a d-wave vortex
We discuss the evolution of the local quasiparticle spectral density and the
related tunneling conductance measurable by the scanning tunneling microscope,
as a function of distance r and angle \theta from the vortex core in a
d_{x^2-y^2} superconductor. We consider the effects of electronic disorder and
of a strongly anisotropic tunneling matrix element, and show that in real
materials they will likely obscure the ~1/r asymptotic tail in the zero-bias
tunneling conductance expected from the straightforward semiclassical analysis.
We also give a prediction for the tunneling conductance anisotropy around the
vortex core and establish a connection to the structure of the tunneling matrix
element.Comment: 9 pages REVTeX + 5 PostScript figures. For related work and info
visit http://www.pha.jhu.edu/~fran
Point-Contact Spectroscopy in MgB_2: from Fundamental Physics to Thin-Film Characterization
In this paper we highlight the advantages of using point-contact spectroscopy
(PCS) in multigap superconductors like MgB_2, both as a fundamental research
tool and as a non-destructive diagnostic technique for the optimization of
thin-film characteristics. We first present some results of crucial fundamental
interest obtained by directional PCS in MgB_2 single crystals, for example the
temperature dependence of the gaps and of the critical fields and the effect of
a magnetic field on the gap amplitudes. Then, we show how PCS can provide
useful information about the surface properties of MgB_2 thin films (e.g. Tc,
gap amplitude(s), clean or dirty-limit conditions) in view of their
optimization for the fabrication of tunnel and Josephson junctions for
applications in superconducting electronics.Comment: 11 pages, 7 figures; Proceedings of 6th EUCAS Conference (14-18
September 2003, Sorrento - Italy