Anisotropic Supercurrent in Strained Graphene Josephson Junction

The Weyl-Dirac fermions in graphene-based SG/I/SG (SG denoting superconducting graphene; I, an insulator) junctions subjected to strains become highly asymmetric. The effect of the strain-induced symmetry change of the fermions on the supercurrent is studied. The highly anisotropic velocity near the critical deformation causes the critical current parallel to the direction of strain to oscillate as a function of gate voltage at a very high frequency. The same anisotropic velocity destroys the oscillation of the gate-dependent critical current when the current is perpendicular to the direction of strain. The direction-dependent supercurrent is due to the strain turning the two-dimensional massless relativistic electrons into nearly one-dimensional massless relativistic fermions near the critical deformation. This work reveals that a new effect can be induced by applying strain on a graphene-based Josephson junction.