The irreversible response of a ferromagnetic pervoskite SrRuO3 with a Curie temperature TC = 160 K has been characterized experimentally by measuring the temperature dependence of the field cooled and zero field cooled moments over the temperature interval 5 K≤T≤180 K; in a sequence of applied fields up to the coercive field, and also the major hysteresis loop over the field range ∣ha∣≤40 kOe at a sequence of temperatures which span the ordered phase. The data have been analysed within the framework of a generalized version of the Preisach model of hysteresis which combines thermal fluctuations with the growth of the free energy barriers below TC. The numerical simulations replicate all of the principal structural systematics of the data, and yield details of the spectrum of Barkhausen instabilities in this material.

Itinerant ferromagnetic SrRuO3 with a Curie temperature TC 160.7 K was prepared by a conventional solid reaction method. Its zero-field-cooled (ZFC) magnetization and field-cooled (FC) magnetization were measured over a temperature interval from 5–180 K, in a sequence of applied fields up to coercivity. The major hysteresis loops were measured over a range of temperatures, which span the ordered phase. An empirical model was proposed to analyze the ZFC behaviors by means of coercivities at different temperatures. The calculated ZFC magnetization is consistent with the measured ZFC magnetization. Different ZFC magnetization behaviors were explained by using this model. The results indicate that the various ZFC behaviors originate from the comparison between the temperature dependence of FC magnetization and that of coercivity.

Zero-field-cooled (ZFC) magnetization, field-cooled (FC) magnetization, ac magnetic susceptibility and major hysteresis loops of itinerant ferromagnet SrRuO3 have been measured at magnetic ordering temperatures ranging from 5 to 160 K. An empirical model is proposed to calculate the measured ZFC magnetization. The result indicates that the calculated ZFC magnetization compares well with the measured one. Based on the generalized Preisach model, both the ZFC and FC curves are reproduced by numerical simulations. The critical temperature and critical exponents are determined by measuring the ac magnetic susceptibility in different bias magnetic fields at temperatures in the vicinity of the point of phase transition.

From the measurements of the ac susceptibility of SrRuO3, we determine the critical temperature TC=159.7 ± 0.2 K and critical exponents δ = 2.50 ± 0.15 (from the critical isotherm orδ= 3.17 ± 0.20 (from magnetization versus magnetic field at Curie temperature), γ+β = 1.50±0.05 (from the temperature dependence of the internal field of the crossover line), and γ = 0.96 ± 0.05 (from the temperature dependence of the susceptibility along the same line). These exponent values are very close to those predicted by the mean field model.

Zero-field-cooled (ZFC) magnetization, field-cooled (FC) magnetization and coercive fields of Sr1-x Cax RuO3, with x = 0.0, 0.2, 0.4 and 0.6, have been measured over the magnetic ordering temperature, in a sequence of applied fields. An empirical model has been proposed to analyze ZFC behaviors. The calculated ZFC magnetization is in agreement with the measured one. Different ZFC behaviors have been explained by means of the empirical model.