Specular Andreev reflection of asymmetric fermions in graphene under strain

This work investigates the effect of the uniaxial strain on the tunneling conductance in a strained graphene superconductor where strain is applied in the armchair direction. Based on the Tight-Binding model, applying strain in the armchair direction gives rise to the asymmetric massless fermions as the carriers. Their velocities depend on their directions controlled by strain. Using the BTK theory, the conductances of strained graphene N/S junctions can be determined. As a result, we find that the current flowing perpendicular to the direction of strain depends linearly on strain, with the positive slope. But the current flowing parallel to the direction of strain depends linearly on strain, with the negative slope. This linear behavior is significant for applications of superconductor-based nanomechanical electronic devices.