Preparation of TlBa2Ca2Cu3O9±δ high T c thin films by laser ablation in combination with thermal evaporation of thallium oxide

TlBa2Ca2Cu3O9±δ high Tc thin films were prepared on MgO 〈100〉 surfaces by a combination of laser ablation from a stoichiometric Ba2Ca2Cu3Ox target and the thermal evaporation of thallium oxide. X-ray diffraction measurements showed that the films consisted of predominantly c axis oriented TlBa2Ca2Cu3O9±δ, and scanning electron microscopy revealed that the surfaces had a flat, platelike morphology. The ac inductive measurements indicated that the onset of superconductivity occurred at 117 K with a transition width (10%–90%) of ∼3 K. Zero resistivity was reached at 120 K. The critical current density was ∼3×104 A/cm2 at 110 K.