Observation of non-sinusoidal current-phase relation in graphene Josephson junctions

TL;DR

This paper reports direct measurements of the current-phase relation in graphene-based Josephson junctions, revealing a forward skewed behavior consistent with Dirac fermion predictions, and analyzing its dependence on critical current and temperature.

Contribution

It provides the first phase-sensitive measurements showing non-sinusoidal current-phase relations in graphene Josephson junctions, confirming theoretical predictions.

Findings

Current-phase relation is forward skewed in graphene junctions.

Skewness increases with critical current.

Skewness decreases sharply with temperature.

Abstract

We present direct measurements of the current-phase relation for lateral Josephson junctions with a graphene barrier, obtained by a phase-sensitive SQUID interferometry technique. We find that the current-phase relation is forward skewed with respect to the commonly observed sinusoidal behavior for short junctions in the quasi-ballistic transport regime, consistent with predictions for the behavior of Dirac fermions in a Josephson junction. The skewness increases with critical current and decreases sharply with increasing temperature.