Results are presented for study of nonlinear magnetization of a sintered YBa2Cu3O7−y pellet of different thickness of a sample subjected to very low magnetic field. On cooling the sample belowTc in zero field a change, in the oscillatory structure of harmonics in increasing dc field is observed in very low ac magnetic field. The effect of finiteness of the sample on the oscillatory structure and on the hysteresis of harmonics is also studied. The results are explained qualitatively.
