Investigating the Temperature Dependence of Hysteresis and Thermal Relaxation in a Ferromagnetically Ordered Perovskite

Measurements of magnetic relaxation isotherms were performed as a function of magnetic field and temperature on an exchange-bond-disordered ferromagnetic perovskite Ca_0.2Sr_0.8RuO₃, over an observation time window 10 slestles10⁴ s, and over a wide range of temperatures which spanned the entire irreversible phase. A plot of Tln(t_r/tau₀) as a function of holding field -H _a was constructed from the times t_r at which the measured relaxation isotherms reversed sign. The plot was interpreted with the aid of numerical simulations based on a model collection of two-level subsystems, which showed that the temperature dependence of the magnetic response of this perovskite was shaped by the coexistence of thermal fluctuations and the explicit evolution of the free energy landscape with temperature, and which yielded estimates for the thermal fluctuation field and for the mean intrinsic dissipation barrier as functions of temperature