Andreev processes in mesoscopic multiterminal graphene Josephson junctions

There is growing interest in using multiterminal Josephson junctions (MTJJs) as a platform to artificially emulate topological phases and to investigate superconducting mechanisms such as multiplet Cooper pairings. Current experimental signatures in MTJJs have led to conflicting interpretations of the salient features. In this work, we report a collaborative experimental and theoretical investigation of graphene-based four-terminal Josephson junctions. We observe resonant features in the differential resistance maps that resemble those ascribed to multiplet Cooper pairings. To understand these features, we model our junctions using a circuit network of resistively and capacitively shunted junctions (RCSJs). We find that the RCSJ model successfully reproduces the observed multiplet features. Therefore, our study suggests that differential resistance measurements alone are insufficient to conclusively distinguish resonant Andreev reflection processes from semiclassical circuit-network effects.

Automated summary

There is a growing interest in using multiterminal Josephson junctions to emulate topological phases and investigate superconducting mechanisms. However, the interpretation of experimental signatures in MTJJs has been conflicting. In this study, graphene-based four-terminal Josephson junctions were investigated experimentally and theoretically. Resonant features in the differential resistance maps were observed and successfully reproduced using a circuit network model. The study suggests that differential resistance measurements alone cannot distinguish resonant Andreev reflection processes from semiclassical circuit-network effects.