Superconductivity and transport behavior of laser ablated Au-added YBa₂Cu₃O_7-δ thin films

Abstract

We report here a systematic investigation of superconducting properties of Au-added YBa₂Cu₃O_7-δ (YBCO) thin films in situ grown by pulsed laser ablation method. Films are highly c-axis oriented while the corresponding bulk samples contain multiphases. The superconducting transition temperature T_c of films remains close to 90 K even for large concentration of Au (up to 10% by weight) and the critical current denisty J_c is about 5×10⁶ A cm^-2 at 77 K (in self-field) with higher reproducibility when compared with that of undoped films of YBCO on <100> LaAlO₃. Preliminary investigations indicate that Au gets rejected by the grains and dopes the grain boundaries thus improving the stability of the boundaries and hence of the films. Our result also demonstrates that pulsed laser deposition can be used to grow films of compounds that generally do not form as a single phase in bulk by the conventional solid state methods and hence offers unique possibilities in terms of exploring structure-property relationships in thin films.