Dimensional crossover effect in j_c characteristics of chemical vapor deposition processed yba₂cu₃o_7-δ films

The critical current densities of chemical vapor deposition (CVD) processed YBa₂Cu₃0₇-<5 films were resistively measured in fields up to 13 T and in a temperature range from 4.2 to 77.3 K. For B perpendicular to the c-axis (2?_L c), an anomaly in the temperature dependence of J_c was observed at T_d = 50-60 K and the field dependence of J_c drastically changed at T_d. Since T_d was almost in agreement with the estimated dimensional crossover temperature T_co, it is sug gested that the change of dimensionality influences the J_c properties.