Deposition of epitaxial thin films of Nd_1.85Ce _0.15CuO_4-y by laser ablation

Abstract

Thin films of the electron-doped superconductor Nd1.85 Ce 0.15 CuO4-y have been deposited on (100) SrTiO3 substrates at 780°C using the laser ablation technique. The deposited films are very smooth and show epitaxial growth with the c axis normal to the substrate. The transport properties of the films are very sensitive to the concentration of oxygen vacancies. Films deposited and cooled in the presence of 150 mTorr O2 exhibit localization behavior with no evidence of superconductivity down to 5 K. Superconductivity is observed on vacuum annealing the films in situ after deposition. Films with optimum concentration of oxygen vacancies show a superconducting onset temperature of 21 K and Tc (R=0) of 20 K, with a critical current density of 2×105 A/cm2 at 5.5 K in zero magnetic field.