A simple approach to the First Order Reversal Curves (FORC) of two-phase magnetic systems

The features that commonly appear in the First Order Reversal Curves (FORC) of magnetic composites, consisting of a hard and a soft phase, are reproduced by a simple mean-field approach in the limit of weak coupling. In this case the features corresponding to each phase are distinct and the effect of the interactions appears as biasing field on the soft phase and a coercivity reduction of the hard one. Interactions produce additional twin (positive/negative) interference features in the region of the (H, H_R) FORC diagram where there is a strong dependence on H through the soft phase and on H_R through the hard phase. The slope and the intensity of these twin features depend on interaction strength.