Graphene Josephson diodes from asymmetric disorder

Josephson diodes are non-reciprocal superconducting devices characterized by different switching currents depending on the current flow direction. They recently attracted considerable theoretical and experimental attention, in view of their possible application as rectifying elements in the field of superconducting electronics, and as probes to investigate symmetry breaking mechanisms in mesoscopic systems. In this work, we show that graphene Josephson junctions provide rectification of supercurrent with an efficiency exceeding 20%. The effect appears applying a mT out-of-plane magnetic field and is enhanced close to the nodes of the Fraunhofer interference pattern. Our findings are consistent with a theoretical model that considers long-range scattering potentials in the junction as the symmetry-breaking mechanism, which yields supercurrent rectification in highly transparent junctions. While graphene stands out as an ultra-clean transmission medium, our work shows that unavoidable residual disorder is sufficient to promote this effect.