Frequency and Field Dependencies of Susceptibilities of High Tc Superconductor YBCO

The temperature dependence of the first and third harmonic susceptibilities has been measured on a melt-textured YBCO for different frequencies and amplitudes of the ac magnetic field. The behavior of the experimental curves has been compared with the results obtained from the model incorporating both the concepts of Collective Creep and critical state. The predictions of the model for fundamental and third harmonic susceptibilities were consistent with the experimental data.