Deposition-temperature dependence of vortex pinning property in YBa₂Cu₃O₇+BaHfO₃ films

Improvement of critical current density (Jc) in magnetic fields is required in YBa₂Cu₃O₇ films, and process parameters should be optimized for controlling pinning centers. In the present study, a deposition temperature was varied in pulsed laser deposition of YBa₂Cu₃O₇+BaHfO₃ films to control the nanorod structure, and its influence on Jc was analyzed. The YBa₂Cu₃O₇+BaHfO₃ film deposited at 850°C exhibited pinning force maximum (F_p,max.) as high as 413GN/m³ at 40 K, while the F_p,max. for the deposition temperature of 850°C at 77K was smaller than that in the YBa₂Cu₃O₇+BaHfO₃ film deposited at 900°C. A critical temperature decreased and matching field increased with decreasing the deposition temperature. Increase in deposition temperature is effective in improving the F_p,max. in high temperatures, since the critical temperature and matching field dependences of Jc value dominate the F_p,max. On the other hand, low deposition temperature improves the F_p,max. in low temperatures since the Fp shift in accordance with matching field is dominant to the F_p,max. Thus, the deposition temperature should be set in pulsed laser deposition of YBa₂Cu₃O₇ films containing nanorods considering the Jc variation with critical temperature and matching field.