Topological Superconductivity in CuxBi2Se3

TL;DR

This paper provides experimental evidence of topological superconductivity in CuxBi2Se3, indicated by zero-bias conductance peaks and Majorana fermions, along with an observed pseudogap phenomenon.

Contribution

It demonstrates the presence of topological superconductivity in CuxBi2Se3 through spectroscopic evidence and theoretical analysis, advancing understanding of topological states in doped topological insulators.

Findings

Zero-bias conductance peak indicating unconventional superconductivity

Evidence for Majorana fermions in CuxBi2Se3

Observation of a pseudogap below 20 K

Abstract

A topological superconductor (TSC) is characterized by the topologically-protected gapless surface state that is essentially an Andreev bound state consisting of Majorana fermions. While a TSC has not yet been discovered, the doped topological insulator CuxBi2Se3, which superconducts below ~3 K, has been predicted to possess a topological superconducting state. We report that the point-contact spectra on the cleaved surface of superconducting CuxBi2Se3 present a zero-bias conductance peak (ZBCP) which signifies unconventional superconductivity. Theoretical considerations of all possible superconducting states help us conclude that this ZBCP is due to Majorana Fermions and gives evidence for a topological superconductivity in CuxBi2Se3. In addition, we found an unusual pseudogap that develops below ~20 K and coexists with the topological superconducting state.