MAGNETOMICROWAVE ABSORPTION STUDY OF FLUX DEPINNING IN HG0.7PB0.3BA2CA2CU3O8 SUPERCONDUCTOR

The microwave absorption in the superconducting state of single-phase Hg0.7Pb0.3Ba2Ca2Cu3O8+x having a T-c of 133 K is shown to depend linea rly on the square root of the DC magnetic field strength with a change of slope occurring at a DC magnetic field B which corresponds to an onset of an irreversibility in the field dependence of the microwave a bsorption. A measurement of the temperature dependence of B enables a determination of an H-T irreversibility line at 9.2 GHz. A comparison of the magnetic-field-induced dissipation with that the Y-Ba-Cu-O ind icates that the Hg-Pb-Ba-Ca-Cu-O material has a larger pinning barrier to flux detrapping at 77 K.