The rotational magnetic process and effects of gamma-irradiation on vortexflux pinning in Tl-2223 at low temperatures

Magnetization vector measurements were carried out in a polycrystalline sam ple of Tl-2223 superconductor in fixed fields at low temperatures. Demonstr ating the broad distribution in the vortex flux pinning, the vortex flux de nsity B was seen to consist of two component: the rotational component B-R turns rigidly with sample rotation and the frictional component B-F stays a t fixed angle theta(F) relative to the applied held H. The pinning torques per vortex were calculated as a function of H at constant temperature. The gamma-irradiated sample shows an increase in pinning torque of ratio seven to one at temperatures 4.2 K and 25 K compared to an unirradiated sample; t his is due to defects induced by the gamma irradiation.