Theory of tunneling spectroscopy in a superconducting topological insulator

Highlights: •We show tunneling conductance for possible parings of superconducting CuxBi2Se3. •A zero-bias conductance peak can appear in this system. •This is because the surface-state transition in the momentum space. •The surface state transition stems from surface Dirac fermions in the normal state. -- Abstract: We calculate tunneling conductance of normal metal and superconducting topological insulator CuxBi2Se3 junctions for the possible pairing symmetries. In the presence of gapless Andreev bound states (ABSs), the tunneling conductance shows a zero-bias peak even for the three-dimensional full-gap superconducting state. This zero-bias conductance peak stems from the enhancement of the surface density of states induced by the surface-state transition in momentum space