Ac magnetic response of MgB2 bulk superconductor based on the Anderson-Kim model

Magnetic response of an intermetallic bulk superconductor MgB2 was carried out by use of ac susceptibility and ac magnetization measurements. The theoretical model calculations corresponding to the measurements were obtained employing the Anderson-Kim model. The measured susceptibilities, *yn = *yn' + i*yn' (n = 1, 3, 5, 7), as a function of temperature with various H, fields agree well with model calculations. The comparisons of ac magnetization measurement at different temperatures with corresponding model calculations also show satisfactory agreements. In addition, the temperature-dependent of critical current density was predicted from experimental data. This relation was shown to obey the almost quadratic power relation.