Anomalous Temperature Dependence of the Upper Critical Magnetic Field in Electron-Doped High-Temperature Superconductor

Abstract

We present resistivity measurements of the upper critical field as a function of temperature for Nd2-xCexCuO4+δ/SrTiO3single crystal films near antiferromagnetic-superconducting phase boundary (x= 0.14) in magnetic fields up to 90kOe at temperatures down to 0.7K. The data are well described by a two-band/two-gap model for a superconductor in the dirty limit.