Highly oriented superconducting Tl-Ca-Ba-Cu oxide thin films with 2-1-2-2 phase

Abstract

Thin films of the Tl-Ca-Ba-Cu-O system with 2-1-2-2 phase have been prepared stably on MgO substrates by rf magnetron sputtering and post-annealing. The post-annealing of the films was carefully carried out in order to reduce the effect of evaporation of Tl. The annealed films showed a c-axis-oriented structure perpendicular to the substrates. The highest zero-resistance temperature of the films was 102 K. The highest critical current density obtained so far was 1.2×105 A/cm2 at 77 K.