Coherent quasiparticle tunneling in d-wave superconductor SIS junctions -: art. no. 132507

Coherent quasiparticle tunneling characteristics are numerically calculated for a superconductor/insulator/superconductor (SIS) tunnel junction with a d-wave order parameter. It is found that in coherent tunneling the differential conductance dI/dV exhibits a very sharp peak at the superconducting gap voltage, showing a sharp contrast to the case of incoherent tunneling, where the dI/dV peak is very broad. The sharp dI/dV peak is in good agreement with experimental results for intrinsic Josephson junctions of Bi2Sr2CaCu2O8+delta. It is also found that when a small amount of incoherent tunneling is involved, the tunneling characteristics change abruptly to those of incoherent tunneling. These results imply that the tunneling in the intrinsic Josephson junctions is mostly coherent.