Theory of tunneling spectroscopy in a superconducting topological insulator

TL;DR

This paper theoretically investigates tunneling conductance in normal metal and superconducting topological insulator junctions, revealing how surface states induce a zero-bias conductance peak across different pairing symmetries.

Contribution

It provides a theoretical framework for understanding tunneling spectroscopy in topological insulators with various pairing symmetries, highlighting the role of surface states.

Findings

Zero-bias conductance peak observed in all pairing states with gapless ABSs.

Surface-state transition enhances surface density of states.

Zero-bias peak persists even in full-gap superconducting states.

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.