Nonlocal Josephson coupling and current redistribution in a large-area graphene multiterminal Josephson junction

Abstract

Multiterminal Josephson junctions (MTJJs) extend conventional two-terminal Josephson physics to devices defined by multiple superconducting phases, where rich phenomena have been predicted. However, in conventional MTJJs, superconducting transport is often dominated by local coupling between neighboring leads, obscuring physics that goes beyond simple connectivity. Here, we realize a multiterminal Josephson network in a graphene Hall bar geometry with micron-scale dimensions, enabling substantial nonlocal coupling between distant terminals. Our key observation is a pronounced negative differential longitudinal resistance (NDLR) in the four-probe response near switching currents, while no such feature appears in two-terminal measurements. We reproduce the NDLR response with a network containing the interplay between two distinct forms of nonlocality: nonlocal Josephson coupling, which determines the switching sequence of the superconducting network, and nonlocal normal-state conductance, which redistributes current after different regions switch. Our results highlight the potential of the emergent NDLR for characterizing superconductor--semiconductor hybrid systems and for nonlinear circuits. Further, this Josephson Hall bar geometry provides a platform for exploring the interplay between mesoscopic superconductivity and many-body ground states in graphene-based heterostructures.