Differential conductance in normal-metal/insulator/metal/d-wave superconductor junction carrying a supercurrent

This paper applies the Bogoliubov--de Gennes equation andthe Blonder--Tinkham--Klapwijk approach to study the oscillatorybehaviour of differential conductance in a normal metal/insulator/metal/d-wavesuperconductor junction carrying asupercurrent I_s. We find that (i) a three-humped structureappears at a nearly critical supercurrent I_s and z ≈0.5 for the normal metal/insulator/metal/d_x² + y²-wavesuperconductor junction; (ii) the zero-bias conductance peak splitsinto two peaks with sufficiently large applied current for the normalmetal/insulator/metal/d_xy-wave superconductor junction; (iii)the conductance spectrum exhibits oscillating behaviour with thebias voltage and the peaks of the resonances are suppressed byincreasing supercurrent I_s.