Magnetocaloric properties of compounds with first order phase transition: Hysteresis effect

In this paper we theoretically discuss the magnetocaloric effect in compounds undergoing first order phase transition, taking into account the hysteresis effect. For this purpose we use a microscopical model of localized magnetic moments including the magnetoelastic interaction. Our calculations show that in compounds undergoing first order transition with large magnetoelastic coupling, the magnetocaloric potentials ΔSiso and ΔTad depend on the direction of the temperature variation. Moreover, our calculations also show that the magnetocaloric potential ΔSiso around a first order phase transition can be calculated using magnetization data via the Maxwell relation only if the hysteresis is negligible.

► Description of the magnetocaloric effect around the first order transition.
► Microscopical description of the hysteresis effect.
► Validity of the Maxwell relation to determine the magnetocaloric potentials.
► The best magnetic materials suitable to be used as magnetic refrigerant.