Preparation and characterization of Tl2Ba2CaCu2O8 thin films by laser ablation and thallium diffusion

We report here the growth of Tl2Ba2CaCu2O8 thin films by a combination of laser ablation and thallium diffusion on [001] MgO substrates. We find that the process configuration and sintering temperatures for thallium diffusion are of paramount importance in achieving single phase thin films. From x-ray diffraction analysis, the films have a highly preferred orientation with the c crystal axis perpendicular to the surface of the substrate. A typical film has a Tc(onset) = 120 K, Tc(midpoint) = 115 K, and Tc(zero) = 109 K. The critical current density for a film, estimated from hysteresis loop and the Bean Model, is greater than 105 A/cm2 at 5 K in zero applied field.