Preparation and Characterization of Pulsed Laser Deposited HTSC Films

Abstract

High Tc superconductor films were prepared by laser deposition. Epitaxial YBaCuO films with high critical current density are obtained for a uniform laser beam energy density of about 4 J/cm2, a substrate temperature above 730°C and an oxygen pressure of 0.3 to 0.5 mbar. Using identical parameters, LaA103 interlayers grow epitaxially on the YBaCuO films and can therefore be used as insulating layers in multi-layer structures. For the Bi(Pb)SrCaCuO system, both the 80 K and the 110 K phase can be prepared in-situ with inductively measured 111's of 77 K and 80 K, respectively. A subsequent annealing step improves these values. For the 110 K phase a Tc(R = 0) of 98 K was obtained. Whereas the critical current densities in the Bi(Pb)SrCaCuO films must still be improved, the epitaxial YBaCuO films show high critical current densities as 5 x 106 A/cm2 at 77 K and zero field or 5 x 107 A/cm2 at 4.2 K and 7 T (for the magnetic field in the film plane). The critical current densities are affected by defects introduced by ion irradiation.