Analyses of the electromagnetic properties of oxide superconductorsby the SRPM method

摘要

ΔZ (the difference in the impedance of a solenoid coil with and without a superconductive sample) of 0, 10, 20 and 30 wt% Ag-doped YBaCuO (c-axis oriented) and a Bi-based sintered sample were measured by the SRPM method between 200 Hz and 1 MHz at room temperature and liquid N2 temperatures. At room temperature, frequency dependence of ΔZ was observed in both samples. These dependencies were analyzed using a serial circuit having the same resistance and inductance as the samples by which the existence of ΔZ was confirmed. Below Tc , only ΔZ of a Bi-based sample was measured between 200 Hz and 1 MHz. ΔR (the real part of ΔZ) was evaluated as a function of frequency(f). ΔR from 0.25 to 1 kHz is assumed to be proportional to f2 (normal skin effect). ΔR from 1 kHz to 50 kHz is proportional to f5/3 (anomalous skin effect). ΔR from 50 kHz to 700 kHz is proportional to f2/3 (anomalous skin effect). It was found that ΔR between 1 kHz and 700 kHz agrees with the property obtained by the equation confirming that it is in the region of anomalous skin effect