A study on the tunneling spectroscopy of an N−pS junction and an N−hS junction

We study the complete tunneling spectroscopy of a normal metal/p-wave superconductor junction (N−pS) and a normal metal/heterostructure superconductor junction (N−hS), using the Blonder–Tinkham–Klapwijk (BTK) method. We find that, for a p-wave superconductor with non-trivial topology, there exists a stable quantized zero-bias conductance peak, and for heterostructure superconductors with non-trivial topology, the emerging zero-bias conductance peak is non-quantized and usually has a considerable gap to the quantized value. Furthermore, the latter is sensitive to parameters, especially to spin–orbit coupling and the s-wave pairing potential. All results of the N−hS junction we obtained suggest that the observation of a small zero-bias conductance peak, instead of a quantized zero-bias conductance peak, in current tunneling experiments is a natural result. Based on the experiments' parameters, we find that only by varying the strength of the spin-orbit coupling to be several times smaller than the reported one, can the zero–bias conductance peak be as small as the reported one. Furthermore, the results we obtained suggest that both a stronger spin–orbit coupling and proximity s-wave superconductor with a relatively weaker pairing potential can produce a much more striking zero-bias conductance peak (compared to the experiments), even an almost quantized one. As s-wave superconductors are common in nature, this prediction can be verified using current experiments. (paper)