AC MAGNETIC-FIELD-INDUCED MICROWAVE-ABSORPTION IN HIGH-TEMPERATURE SUPERCONDUCTOR TL2BA2CA2CU3OX

The application of an a.c. magnetic field from 8 to 40 G peak to peak amplitude in the frequency range from 25 to 100 KHz to Tl2Ba2Ca2Cu3Ox below T-c causes a substantial increase in the absorption of microwave energy at 9.2 GHz measured as the difference in absorption between th e a.c. held on and off. The absorption intensity decreases as the temp erature approaches T-c from below and increases with frequency and the amplitude of the magnetic held. A small increasing d.c. magnetic held gradually reduces the a.c. magnetic held induced microwave absorption . These results are shown to be consistent with an absorption mechanis m arising from a.c. held induced flux jumps through current loops form ed by weak links.