Point-contact Andreev reflection spectroscopy on the misfit phase superconductors (PbSe)1.12(TaSe2) doped with Cl or Br

Abstract

We report point-contact Andreev reflection spectroscopy studies on possible topological superconductor candidates Cl- (Br-) doped (${\mathrm{PbSe})}_{1.12}({\mathrm{TaSe}}_{2})$ with superconducting transition temperature ${T}_{c}\ensuremath{\sim}$ 1.2 K. A common double-peak feature is observed for the conductance curves at low temperature in the absence of a zero-bias conductance peak. We analyze conductance curves with the Blonder-Tinkham-Klapwijk model and the extracted superconducting gap follows a typical Bardeen-Cooper-Schrieffer temperature- and field-dependent behavior, with $2{\mathrm{\ensuremath{\Delta}}}_{0}/{k}_{B}{T}_{c}\ensuremath{\approx}3.7$ and 3.8 for Cl and Br doping, respectively. Our results strongly suggest that both Cl- and Br-doped $({\mathrm{PbSe})}_{1.12}({\mathrm{TaSe}}_{2})$ are fully gapped superconductors in an intermediate-coupling regime.