Resistive transport in a mesoscopic proximity superconductor

TL;DR

This paper reviews transport phenomena in normal metals coupled with superconductors, highlighting the proximity effect, Josephson coupling, and mesoscopic fluctuations, with experimental observations of magnetoresistance oscillations and resistance re-entrance explained by quasiclassical theory.

Contribution

It provides a comprehensive review of mesoscopic proximity effects in superconductor-normal metal systems, including experimental results and theoretical explanations.

Findings

Observation of large h/2e-periodic magnetoresistance oscillations.

Temperature-dependent decay of oscillations following a 1/T law.

Re-entrance of metallic resistance below the Thouless energy.

Abstract

We review transport measurements in a normal metal (N) in contact with one or two superconducting (S) islands. From the experiment, we distinguish the Josephson coupling, the mesoscopic fluctuations and the proximity effect. In a loop-shaped N conductor, we observe large h/2e-periodic magnetoresistance oscillations that decay with temperature T with a 1/T power-law. This behaviour is the signature of the long-range coherence of the low-energy electron pairs induced by the Andreev reflection at the S interface. At temperature and voltage below the Thouless energy $\hbar D / L^2$, we observe the re-entrance of the metallic resistance. Experimental results agree with the linearized quasiclassical theory.