Magnetotransport in superconductor-graphene-superconductor Josephson junctions of various aspect ratios

Superconducting proximity effect in superconductor(S)-Graphene(G)-superconductor(S) junctions has been widely investigated since it provides a unique platform to study the fascinating physics of superconductivity carried by Dirac fermions. We investigated the superconducting proximity effect in ballistic SGS Josephson junction by measuring the magnetotransport in devices of different width/length ratios. BN encapsulated graphene devices with various aspect ratios are fabricated with edge-contacted superconducting electrodes. In order to obtain highly transparent electrical contact and high critical field, we deposited niobium nitride (70nm)/niobium (3nm)/ tantalum (3nm) trilayer for the superconducting electrodes by DC magnetron sputtering. We will discuss the dependence of superconducting critical current magneto-oscillation on device geometry.