Microwave absorption in weak magnetic fields in high Tc ceramics near the superconducting transition temperature
A. I. Veinger, S. I. Goloshchapov, and S. G. Konnikov
A. F. Ioffe Physicotechnical Institute, Russian Academy of Sciences, 194021, St. Petersburg
A. S. Kheifets
The Flinders University of South Australia, Adelaide, Australia
(Received March 24, 1992; accepted July 29, 1992)
Themicrowave absorption in weak magnetic fields has been studied inyttrium- and bismuth-based high-Tc ceramics near the superconducting transition temperature.The dc resistance was measured simultaneously. Comparison of the temperaturedependence of the microwave-absorption signal with that of the dcresistance reveals that the absorption signal disappears completely at T=Tc.The temperature dependence of the absorption signal was found tobe A ~ (Tc – T)4. It is concluded that the superconducting phases inthe ceramics studied have fixed superconducting transition temperatures. These temperaturesare found from the temperature dependence of the microwave-absorption signal.
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