Electromagnetic properties of ceramic high-Tc superconductor in critical state
Voloshin I. F. , Makarov N. M. , Fisher L. M. , Yampol'skii V. A.
A method is proposed for directly measuring the critical current density /,, of a ceramic high-Fc superconductor as a function of the magnetic field Η through the use of a low-frequency electromagnetic signal as a probe. In a model of the critical state, the surface impedance of a ceramic sample is proportional to the function