We show that the zero-bias conductance peak observed in tunnel and point junctions of cuprates can be a consequence of "unitary" elastic scattering of the carriers by non-magnetic impurities in the vicinity of the junction interface and d-wave symmetry of the order parameter.
We study the tunneling spectra for superconductor-insulator-normal metal (S-I-N) tunnel junctions with an s -wave or a d -wave superconductor within the weak-coupling model. We deduce the temperature behavior of tunneling conductance and their peak positions as well as of the zero-bias conductance. The results obtained allow us to discriminate among the two singlet spin states.
AbstractWe propose a simple phenomenological theory for quantum tunneling of Cooper pairs, in superconductor/insulator/superconductor tunnel junctions, for a regime where the system can be modeled as bosonic particles. Indeed, provided there is an absence of quasiparticle excitations (fermions), our model reveals a rapid increase in tunneling current, around zero bias voltage, which rapidly saturates. This manifests as a zero bias conductance peak that strongly depends on the superconductors temperature in a non-monotonic way. This low energy tunneling of Cooper pairs could serve as an alternative explanation for a number of tunneling experiments where zero bias conductance peak has been observed.
Smearing origin of zero-bias conductance peak in Ag-SiO-Bi2Sr2CaCu2O8+δ planar tunnel junctions: influence of diffusive normal metal verified with the circuit theory