Tunneling Conductance and Surface States Transition in Superconducting Topological Insulators

TL;DR

This paper develops a theory for tunneling spectroscopy in superconducting topological insulators, revealing how surface states transition and produce Majorana fermions that manifest as zero bias peaks in conductance measurements.

Contribution

It introduces a theoretical framework linking topological surface state transitions to observable tunneling conductance features in superconducting topological insulators.

Findings

Surface Andreev bound states are helical Majorana fermions.

Structural transitions in energy dispersions occur with tuning parameters.

Zero bias conductance peaks are robust near transition points.

Abstract

We develop a theory of the tunneling spectroscopy for superconducting topological insulators (STIs), where the surface Andreev bound states (SABSs) appear as helical Majorana fermions. Based on the symmetry and topological nature of parent topological insulators, we find that the SABSs in the STIs have a profound structural transition in the energy dispersions. The transition results in a variety of Majorana fermions, by tuning the chemical potential and the effective mass of the energy band. We clarify that Majorana fermions in the vicinity of the transitions give rise to robust zero bias peaks in the tunneling conductance between normal metal/STI junctions.