Thin film preparation, transport properties and superconductivity of YBa2Cu3O7

The authors report the preparation of high-Tc YBa2Cu3O7 films on single crystalline SrTiO3, LaGaO3, NdAlCaO4, MgO, ZrO2, and Al2O3 substrates by sputtering and laser ablation. In all cases c-axis oriented films with Tc's near 90 K and narrow transitions were obtained. The films grow epitaxially on SrTiO3 and LaGaO3, highly oriented on MgO, ZrO2 and NdAlCaO4 and less oriented on Al2O3. On patterned films the authors obtained jc(77K)=4.106 A/cm2 for films on SrTiO3, 4.104 A/cm2 on NdAlCaO4 and 4.103 A/cm2 on Al2O3 revealing the importance of epitaxial growth. In magnetic fields of 12 Tesla with B//c-axis they find jc(12 T, 20 K)=2.106 A/cm2