Interface effects in superconductor-nanotubes hybrid structures

The objective of the present paper is to investigate the proximity effect in junctions of superconductors with carbon nanotubes. The method is the lattice BdG equations within the Hubbard model. The proximity effect depends sensitively on the connection giving the possibility to control the proximity effect by performing simple geometrical changes in the hybrid systemComment: 12 pages, 19 figure

Resonant propagation of fluxons in corner junctions with triplet pairing symmetry

We present the numerical solutions for the I-V characteristics, and describe the motion of fluxons in a frustrated Josephson junction made of an unconventional triplet superconductor and an s-wave superconductor. In the inline geometry, and long length limit the moving integer fluxon interacts with the bound fractional fluxon but is not able to change its position or polarity. We observe different modes of multifluxon propagation. In the small length limit the moving fluxon is a combination of the stable solutions that exist in the static case and additional steps are introduced in the I-V diagram.Comment: 19 pages, 8 figure

Tunneling conductance in normal metal - triplet superconductor junction

We calculate the tunneling conductance spectra of a normal metal / insulator / triplet superconductor from the reflection amplitudes using the Blonder-Tinkham-Klapwijk (BTK) formula. For the triplet superconductor we assume one special p-wave order parameter having line nodes and two two dimensional $f$-wave order parameters with line nodes breaking the time-reversal symmetry. Also we examine nodeless pairing potentials. The tunneling peaks are due to the formation of bound states for each surface orientation at discrete quasiparticles trajectory angles. The tunneling spectra can be used to distinguish the possible candidate pairing states of the superconductor Sr$_2$RuO$_4$.Comment: 4 pages with 3 figures, presented at the second Euroconference on Vortex Matter in Superconductors, 15-25 September 2001, Crete, Greec

Proximity effect in ferromagnet-superconductor hybrid structures: role of the pairing symmetry

The spatial variations of the pair amplitude, and the local density of states in d-wave or s-wave superconductor-ferromagnet hybrid structures are calculated self consistently using the Bogoliubov-deGennes formalism within the two dimensional extended Hubbard model. We describe the proximity effect in superconductor / ferromagnet (SF) bilayers, FSF trilayers, and interfaces between a superconductor and a ferromagnetic domain wall. We investigate in detail the role played by the pairing symmetry, the exchange field, interfacial scattering and crossed Andreev reflection.Comment: 27 pages, 14 figure

Tunneling current in triplet f-wave superconductors with horizontal lines of nodes

We calculate the tunneling conductance spectra of a normal-metal/insulator/triplet superconductor using the Blonder-Tinkham-Klapwijk (BTK) formulation. Possible states for the superconductor are considered with horizontal lines of nodes, breaking the time reversal symmetry. These results would be useful to discriminate between pairing states in superonductor Sr$_2$RuO$_4$ and also in UPt$_3$.Comment: 12 pages, 7 figure

Charge current in ferromagnet - triplet superconductor junctions

We calculate the tunneling conductance spectra of a ferromagnetic metal / insulator / triplet superconductor from the reflection amplitudes using the Blonder-Tinkham-Klapwijk (BTK) formula. For the triplet superconductor, we assume one special $p$-wave order parameter, having line nodes, and two two dimensional $f$-wave order parameters with line nodes, breaking the time reversal symmetry. Also we examine nodeless pairing potentials. The evolution of the spectra with the exchange potential depends solely on the topology of the gap. The weak Andreev reflection within the ferromagnet results in the suppression of the tunneling conductance and eliminates the resonances due to the anisotropy of the pairing potential. The tunneling spectra splits asymmetrically with respect to $E=0$ under the influence of an external magnetic field. The results can be used to distinguish between the possible candidate pairing states of the superconductor Sr$_2$RuO$_4$.Comment: 15 pages with 8 figure