Conductance fluctuations in mesoscopic normal-metal/superconductor samples

TL;DR

This paper investigates how conductance fluctuations in mesoscopic gold-niobium samples are enhanced by a factor of nearly three when in the superconducting state, confirming theoretical predictions about mesoscopic NS systems.

Contribution

It provides experimental evidence of increased conductance fluctuation amplitude in mesoscopic normal-metal/superconductor samples, validating recent theoretical models.

Findings

Conductance fluctuations are 2.8 times larger in the superconducting state.

Fluctuation characteristics vary with magnetic field strength.

Results agree with theoretical predictions for mesoscopic NS systems.

Abstract

We study the magnetoconductance fluctuations of mesoscopic normal-metal/superconductor (NS) samples consisting of a gold-wire in contact with a niobium film. The magnetic field strength is varied over a wide range, including values that are larger than the upper critical field B_c2 of niobium. In agreement with recent theoretical predictions we find that in the NS sample the rms of the conductance fluctuations (CF) is by a factor of 2.8 +/- 0.4 larger than in the high field regime where the entire system is driven normal conducting. Further characteristics of the CF are discussed.