Thermodynamic aspects of first-order phase transformations with hysteresis in magnetic materials

In this paper we study first-order phase transformations between two stable phases with different crystal structures and magnetic order. The out-of-equilibrium thermodynamics of the hysteretic phase transformation is formulated for a collection of bistable objects by considering the two stable states as two generic phases, say 0 and 1. In the phase coexistence region we compute the magnetization, the entropy and the entropy production. Results are obtained by deriving the model parameters from experimental data on Gd-Si-Ge and giving prediction on temperature driven hysteresis, and on the heat flux with the thermal bath