Conductance Spectra in Graphene-Superconductor Junctions

The conductance spectra of a graphene ribbon and graphene-superconductor(G-S) junctions are investigated, using the tight-binding model and non-equilibrium Green’s function formalism. It is found that the quantized conductance related to graphene’s edge-states is robust against perturbations in the model parameters for a graphene monolayer ribbon with the zigzag boundary. With appropriate model parameter of the spin-orbit interaction strength,a new bound state with odd-frequency symmetry is found in the G-S junction. An enhancement in the zero-energy conductance amplitude is followed.