Electrodynamic features of anisotropic hard superconductors

The low-frequency electromagnetic response of superconducting plates charac terized by strong anisotropy of current-carrying capacity in the plane of t he sample is studied experimentally and theoretically. Measurements are mad e on polycrystalline textured plates of the Y-123 system with the c axis ly ing in the plane of the sample and on a single crystal with a single prefer red direction of twinning boundaries. It is shown that the shape of the cur ves describing the dependence of the relative losses q on the ac field ampl itude h(0) is quite sensitive to the orientation of vector h(0) in the samp le plane. As in the case of isotropic samples, the q(h(0)) dependence is ch aracterized by a single size peak if vector h(0) is oriented along one of t he principal symmetry directions of the anisotropic critical current densit y. If h(0) deviates considerably from principal directions, two size peaks are observed on the q(h(0)) curve. A detailed analysis of the evolution of the q(h(0)) curves upon a rotation of vector h(0) in the sample plane is ca rried out. (C) 2001 MAIK "Nauka/Interperiodica".