Unconventional superconductivity in CuxBi2Se3

TL;DR

This paper investigates unconventional superconductivity in Cu-doped Bi2Se3 through point contact spectroscopy, revealing multiple spectral features and large superconducting gaps indicative of novel pairing mechanisms.

Contribution

It provides experimental evidence of diverse spectral behaviors and large superconducting gaps in Cu0.2Bi2Se3, suggesting unconventional superconductivity.

Findings

Superconducting gap of 0.6 mV from Andreev-reflection spectra

Large gap of ~2 meV observed in tunneling spectra

Zero-bias conductance peaks indicating unconventional pairing

Abstract

We report point contact measurements in high quality single crystals of Cu0.2Bi2Se3. We observe three different kinds of spectra: (1) Andreev-reflection spectra, from which we infer a superconducting gap size of 0.6mV; (2) spectra with a large gap which closes above Tc at about 10K; and (3) tunneling-like spectra with zero-bias conductance peaks. These tunneling spectra show a very large gap of ~2meV (2Delta/KTc ~ 14).