MECHANICAL DISSIPATION AT DIFFERENT ORIENTATION OF MAGNETIC-FIELD IN HIGH-TC SUPERCONDUCTOR

The mechanical dissipation of (Bi0.9Pb0.1)2Sr2Ca2Cu3O10+y and YBa2Cu3O7-x ceramics were measured as a function of the angle theta between the orientation of the transverse magnetic field and the vibrating direction at fixed temperature and magnetic field with the vibrating reed technique. A relation between Q-1 (or f) and the angle theta, i.e. DELTAQ-1 (or DELTAf) approximately (H(a) cos theta)1.5 was found and this indicated that only the magnetic field component parallel to the vibrating direction H(a) cos theta gives rise to the enhancement of internal friction and resonant frequency in ceramic sample. The anisotropic deformation of flux-line-lattice is used to explain the observed results.