Theory of charge transport in diffusive normal metal/conventional superconductor point contacts

Y. Tanaka; A. A. Golubov; S. Kashiwaya

doi:10.1103/PhysRevB.68.054513

← Back to search

Theory of charge transport in diffusive normal metal/conventional superconductor point contacts

Y. Tanaka, A. A. Golubov, S. Kashiwaya

DOI 10.1103/PhysRevB.68.054513 · Physical Review B

T1

Active bibliographic source — not scientific approval

Bibliographic access preserves source history; it does not approve extracted materials or validate reported claims. Review warnings on each occurrence separately.

Abstract

Tunneling conductance in diffusive normal (DN) metal/insulator/s-wave superconductor junctions is calculated for various situations by changing the magnitudes of the resistance and Thouless energy in DN and the transparency of the insulating barrier. The generalized boundary condition introduced by Nazarov [Superlattices and Microstructures 25, 1221 (1999)] is applied, where the ballistic theory by Blonder, Tinkham, and Klapwijk and the diffusive theory by Volkov, Zaitsev, and Klapwijk based on the boundary condition of Kupriyanov and Lukichev are naturally reproduced. It is shown that the proximity effect can enhance (reduce) the tunneling conductance for junctions with a low (high) transparency. A wide variety of dependencies of tunneling conductance on voltage bias is demonstrated including a U-shaped gap like structure, a zero-bias conductance peak, and a zero-bias conductance dip. The temperature dependence of tunneling conductance is also calculated, and the conditions for the reentrance effect are studied.