Estimating spontaneous magnetization from a mean field analysis of the magnetic entropy change

摘要

The magnetocaloric effect is a common property of all magnetic systems, corresponding to a temperature change under adiabatic conditions (ΔT_(ad)) or a change in magnetic entropy in isothermal conditions (ΔS_M), for a given applied magnetic field change. ΔT_(ad) can be directly measured under adiabatic conditions and indirectly estimated from specific heat measurements. ΔS_M can be indirectly estimated from specific heat measurements or magnetization measurements (the usual approach). Early work on the study of ferromagnets used direct measurements of ΔT_(ad) to determine the spontaneous magnetization for a given temperature value. In this work, we use ΔS_M obtained from isothermal magnetization measurements to estimate the spontaneous magnetization, comparing this result to mean-field fittings from a novel scaling method, discussing the validity and usefulness of this approach from considerations from the Landau theory of phase transitions.