Deposition-Temperature Dependence of Vortex Pinning Property in YBa₂Cu₃O₇+BaHfO₃ Films

Abstract

Improvement of critical current density (J_c) 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 J_c was analyzed. The YBa₂Cu₃O₇+BaHfO₃ film deposited at 850°C exhibited pinning force maximum (F_p,max) as high as 413 GN/m³ at 40 K, while the F_p,max for the deposition temperature of 850°C at 77 K 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 J_c value dominate the F_p,max. On the other hand, low deposition temperature improves the F_p,max in low temperatures since the F_p 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 J_c variation with critical temperature and matching field.

 

This Paper was Originally Published in Japanese in J. Japan Inst. Met. Mater. 83 (2019) 320–326.