Non-local Andreev reflection in superconducting quantum dots

Dmitri S. Golubev and Andrei D. Zaikin
Phys. Rev. B 76, 184510 – Published 12 November 2007

Abstract

With the aid of the Keldysh technique, we develop a microscopic theory of non-local electron transport in three-terminal normal metal–superconductor–normal metal (NSN) structures consisting of a chaotic superconducting quantum dot attached to one superconducting and two normal electrodes. Our theory fully accounts for nonequilibrium effects and disorder in a superconducting terminal. We go beyond the perturbation theory in tunneling and derive a general expression for the system conductance matrix, which remains valid in both weak and strong tunneling limits. We demonstrate that the proximity effect yields a decrease of the crossed Andreev reflection (CAR). Beyond the weak tunneling limit, the contribution of CAR to the non-local conductance does not cancel that of the direct electron transfer between two normal terminals. We argue that the temperature dependence of the non-local resistance of NSN devices is determined by the two competing processes—Andreev reflection and charge imbalance—and it has a pronounced peak occurring at the crossover between these two processes. This behavior is in a good agreement with recent experimental observations.

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  • Received 25 July 2007

DOI:https://doi.org/10.1103/PhysRevB.76.184510

©2007 American Physical Society

Authors & Affiliations

Dmitri S. Golubev and Andrei D. Zaikin

  • Forschungszentrum Karlsruhe, Institut für Nanotechnologie, 76021 Karlsruhe, Germany and I.E. Tamm Department of Theoretical Physics, P.N. Lebedev Physics Institute, 119991 Moscow, Russia

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Issue

Vol. 76, Iss. 18 — 1 November 2007

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