Electrical breakdown of a dielectric for the formation of a superconducting nanocontact

TL;DR

This paper investigates how dielectric breakdown in a nanolayer can create a superconducting nanocontact, potentially functioning as a Josephson junction at low temperatures, with specific structural and electrical properties analyzed.

Contribution

It demonstrates the formation of a superconducting nanocontact through dielectric breakdown and analyzes its electrical properties, including coherence length and critical current, in relation to the alloy's parameters.

Findings

Bridge resistance depends on breakdown current

Bridge length equals dielectric thickness (30 nm)

Critical current at 0 K is approximately 2 mA

Abstract

Electrical breakdown of the dielectric nanolayer between film electrodes of niobium and an alloy of 50% indium and 50% tin forms a bridge of this alloy between the electrodes. The bridge resistance depends on the breakdown current. The length of the bridge is equal to the thickness of the dielectric (30 nm), and its diameter is 25 nm. The calculated coherence length of the alloy at 0 K is close to the length of the bridge. The calculated critical current of a bridge with a resistance of 1 {\Omega} at a temperature of 0 K is 2 mA. It is concluded that such a bridge should have the properties of a Josephson contact at a temperature lower than the critical temperature of the alloy (6.5 K).