The ac Magnetic Response of Superconducting YBa2Cu3O7-x

The nonlinear magnetic response of a high-T c superconductor YBa2Cu3O7-x has been investigated by the ac induction method. At temperatures below 80 K, the fundamental and the third-higher harmonic susceptibility components of both the pellet and coarse powder samples strongly depends on the field amplitude. Also, M-H curves exhibit a hysteresis which bears a similarity to that of hysteretic superconductors. These characteristics are absent in well-isolated particles. Around the transition temperature, susceptibility components have a behavior distinct from that at low temperature and the magnetic response is nearly reversible. The observed magnetic behavior is interpreted as a superposition of the bulk property and the effect of weak linkage of superconducting particles.