SUPERCONDUCTING AND EPITAXIAL (TL,PB)SR2CA1-XYXCU2O7 THIN-FILMS BY IN-SITU DEPOSITION

We report the growth of thin films of (Tl,Pb)Sr2Ca1-xYxCu2O7 with x=0- 0.2 by off-axis magnetron sputtering in the presence of thallium oxide vapor. The (Tl,Pb)Sr2Ca1-xYxCu2O7 films are highly c-axis oriented on the pseudocubic (100) surface of LaAlO3 or on (001)NdGaO3. The [100] axes of the films grown on LaAlO3 align to the pseudocubic (100) axes of the substrate while for films on NdGaO3 they are rotated 45-degrees relative to orthorhombic (100) substrate axes. After an in situ heat treatment, undoped (Tl,Pb)Sr2CaCu2O7 films are superconducting at temp eratures up to 82 K, compared with 85 K for the bulk material. Yttrium doping on the calcium site increased the transition temperature as ex pected. The highest transition temperature observed was 86 K for x=0.1 and 93 K for x=0.2.