Magnetic Response of a Single-Crystal Thin Film Bi_2Sr_2CaCu_2Oy
To test the utility of the modified Kim-Anderson model for study of the magnetic response of ceramic superconductors, we measured ac complex susceptibilities x<SUB>n</SUB>=x'<SUB>n</SUB>-ix"<SUB>n</SUB>(n=1, 2, 3, 5, 7) of a single-crystal thin film Bi<SUB>2</SUB>Sr<SUB>2</SUB>CaCu<SUB>2</SUB>O<SUB>y</SUB>, and attempted to simulate the results in the framework of this model. Analyses of x<SUB>n</SUB>, have shown that generation of the higher-harmonics can be reproduced pretty well, where the material parameters k and B<SUB>0</SUB>, the surface barrier ΔH and the lower critical field H<SUB>CI</SUB> involved were used as the fitting parameters. From the even-n harmonic susceptibility x<SUB>2</SUB> which reflects the asymmetric nature of the magnetization curve, we foundthat the critical-current density J<SUB>c</SUB> of the Bi<SUB>2</SUB>Sr<SUB>2</SUB>CaCu<SUB>2</SUB>O<SUB>y</SUB> film depends sensitively on the local flux density B<SUB>i</SUB>. This result is a provoking contrast to the B<SUB>i</SUB>, dependence of J<SUB>c</SUB>. for an YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>y</SUB> film.
粉体および粉末冶金 44(8), 787-791, 1997-08-15
Japan Society of Powder and Powder Metallurgy