Magnetization and Critical Current of Calcium-doped YBa2Cu3O7−x Composite Films

The results of the study of magnetization of Y1−x Ca x Ba2Cu3O7−δ HTS films deposited on the metallic substrate are presented. The magnetization measurements were carried out in a wide temperature range 4–77 K and magnetic fields up to 14 T. Based on critical state model, the analysis of the influence of calcium concentration on the critical current was performed. It was found that the change in Ca concentration causes the decrease in value of critical current density j c . The increase in temperature leads to enhancement of the observed effect. At T = 4.2 K and in the magnetic fields higher than 8 T, the j c reduction was found to be insignificant. This fact may indicate the possibility of j c growth in strong magnetic fields due to increase in carrier concentration caused by replacing Y3+ by Ca2+.