Frequency characteristic of magnetic flux invasion on YBCO superconductor ring specimen

Because the bulk type YBCO superconductor prepared by the MPMG process characterizes high critical current density J(c), it is expected to be applied to various fields. It is important to develop measurement methods of magnetic properties of the high T-c superconductor (HTSC). It is necessary to value not only DC magnetic properties but also AC magnetic properties. So we determined the magnetic properties of the HTSC under an AC magnetic field (5-500Hz). From the experimental results we can understand that there is the first order lag element caused by the flux flow effect, and the magnetic properties in low frequency are ruled by the flux flow.