Hopping Transport in Granular Superconductors

TL;DR

This paper investigates how conductivity in granular superconductors is influenced by hopping mechanisms of electrons or Cooper pairs, highlighting the role of local pairing and constructing a phase diagram for different transport regimes.

Contribution

It provides a detailed analysis of hopping transport in granular superconductors, emphasizing the impact of the superconducting gap and local pairing on conduction.

Findings

Superconducting gap suppresses inelastic cotunneling in electron hopping.

Transport characteristics vary depending on the relation between gap and charging energy.

Constructed a phase diagram outlining different transport regimes.

Abstract

We study the conductivity of granular superconductors in the weak coupling insulating regime. We show that it is governed by the hopping of either electrons or Cooper pairs depending on the relation between the superconducting gap and the charging energy of a single granule. Local superconducting pairing plays an important role in both cases. In particular, in the case of the transport via electron hopping the superconducting gap suppresses the inelastic cotunneling processes. We determine transport characteristics of an array in different regimes and construct the transport phase diagram.