Observation of mesoscopic conductance fluctuations in YBaCuO grain boundary Josephson Junctions

TL;DR

This paper reports the observation of reproducible mesoscopic conductance fluctuations in high-temperature superconductor grain boundary Josephson junctions, highlighting the role of mesoscopic transport and Thouless energy in these systems.

Contribution

It provides new experimental evidence of mesoscopic conductance fluctuations in HTS grain boundary junctions and links them to quasiparticle relaxation and coherent transport mechanisms.

Findings

Reproducible magneto-fluctuations of normal resistance observed

Mesoscopic transport identified as the underlying mechanism

Thouless energy is a key energy scale in these fluctuations

Abstract

Magneto-fluctuations of the normal resistance R_N have been reproducibly observed in high critical temp erature superconductor (HTS) grain boundary junctions, at low temperatures. We attribute them to mesoscopic transport in narrow channels across the grain boundary line. The Thouless energy appears to be the relevant energy scale. Our findings have significant implications on quasiparticle relaxation and coherent transport in HTS grain boundaries.