Year: 2001
Type: article
Abstract: We present a general theory of the superconductive proximity effect in disordered normal-metal--superconducting (N-S) structures, based on the recently developed [M. V. Feigel'man et al., Phys. Rev. B 61, 12 361 (2000)] Keldysh action approach. In the case of the absence of an interaction in the normal conductor we reproduce known results for the Andreev conductance ${G}_{A}$ at an arbitrary relation between the interface resistance ${R}_{T}$ and the diffusive resistance ${R}_{D}.$ In two-dimensional N-S systems, the electron-electron interaction in the Cooper channel of a normal conductor is shown to strongly affect the value of ${G}_{A}$ as well as its dependence on temperature, voltage, and magnetic field. In particular, an unusual maximum of ${G}_{A}$ as a function of temperature and/or magnetic field is predicted for some range of parameters ${R}_{D}$ and ${R}_{T}.$ The Keldysh action approach makes it possible to calculate the full statistics of charge transfer in such structures. As an application of this method, we calculate the noise power of an N-S contact as a function of voltage, temperature, magnetic field, and frequency for arbitrary Cooper repulsion in the normal metal and arbitrary values of the ratio ${R}_{D}{/R}_{T}.$
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2063856975