FIELD-DEPENDENCE AND RELAXATION OF REMANENT MAGNETIZATION IN THIN YBACUO FILMS

The isothermo-remanent magnetic moment M(IR) of YBaCuO thin films is i nvestigated by a SQUID magnetometer. In low magnetizing fields (H-0 < 10 Oe) M(IR) is found to be proportional to the third power of H-0 in disagreement with the usual Bean critical state model which predicts a quadratic dependence. A theoretical description of M(IR)(H-0), taking into account the contribution of the critical current distribution th roughout the sample, gives good agreement with experimental data, from low fields up to saturation (H-0 > 150 Oe). The dependence of the rel axation rate of M(IR) on H-0 is discussed. (C) 1997 Academic Press Lim ited.