Tunneling conductance in topological insulator ferromagnet/dx2+y2+idxydx2+y2+idxy mixed wave superconductor junctions

The tunneling conductance in a topological insulator (TI) ferromagnet/dx2−y2+idxydx2−y2+idxy mixed wave superconductor (FM/dx2−y2+idxydx2−y2+idxy S) junction is studied based on the Blonder–Tinkham–Klapwijk (BTK) theory. It is demonstrated that the conductance strongly depends on the magnetic gap, the superconducting pair symmetry orientation, and the magnitude of the ratio of Δ2/Δ1Δ2/Δ1. Here Δ1(Δ2)Δ1(Δ2) is the absolute pair potential of dx2−y2(dxy)dx2−y2(dxy) component. For a large magnetic gap, the tunneling spectrum is characterized by a dip structure. When α=0.25πα=0.25π, the conductance dip appears at eV=±Δ2eV=±Δ2. Thus, the dx2−y2+idxydx2−y2+idxy pairing symmetry as well as the magnitude of the gap can be determined from the experiment of scanning tunneling spectroscopy.