Weak-coupling Bardeen-Cooper-Schrieffer superconductivity in the electron-doped cuprate superconductors

Abstract

We use in-plane tunneling spectroscopy to study the temperature dependence of the local superconducting gap $\ensuremath{\Delta}(T)$ in electron-doped copper oxides with various ${T}_{c}$'s and Ce-doping concentrations. We show that the temperature dependence of $\ensuremath{\Delta}(T)$ follows the expectation of the Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity, where $\ensuremath{\Delta}(0)∕{k}_{B}{T}_{c}\ensuremath{\approx}1.72\ifmmode\pm\else\textpm\fi{}0.15$ and $\ensuremath{\Delta}(0)$ is the average superconducting gap across the Fermi surface, for all the doping levels investigated. These results suggest that the electron-doped superconducting copper oxides are weak-coupling BCS superconductors.