Internal Entropy Production in Magnetic Systems

In the framework of the mathematically and conceptually simple two-level mean-field model of an electronic spin system characterised by the spin-lattice relaxation time, actual magnetic phenomena have been evaluated within the language of irreversible thermodynamics, namely in terms of internal entropy production. A suitable description of both reversible and irreversible magnetization processes is presented which enables one to distinguish between them. It is suggested that, on the basis of this model, the majority of the phenomena observed in magnetic systems, for example, the construction of hysteresis loops, the energy balance of magnetization processes, the Steinmetz rule, etc., should be experimentally evaluated.