Enhancement of the magnetocaloric effect in composites: Experimental validation

Influence of magnetic interactions between phases on the magnetocaloric effect of composites

“…It has been recently shown theoretically that composite materials constituted by different phases with a second order phase transition can exhibit greatly enhanced refrigerant capacities (RC), and table-like magnetocaloric effect. 13 This has been subsequently confirmed by experimental results by different groups, [14][15][16] finding an outstanding agreement between experimental results and predictions of the models. 16 However, these studies of materials with different magnetic phases do not consider the possible effect of the interactions among the phases, which might alter the response of the materials.…”

“…13 This has been subsequently confirmed by experimental results by different groups, [14][15][16] finding an outstanding agreement between experimental results and predictions of the models. 16 However, these studies of materials with different magnetic phases do not consider the possible effect of the interactions among the phases, which might alter the response of the materials. The agreement between experiment and the models which do not consider interactions might either be due to a much reduced value of magnetic interactions in the systems under study, or to a very limited influence of interactions on the response of the composite.…”

“…This shift in x opt is a general behavior for all the studied values of applied field and for all DT c . In order to compare these results emerging from numerical simulations with experimental data, we have studied the RCI(x) curves recently obtained by Paticopoulos et al 16 for a biphasic composite. Even if the non-interacting model was able to accurately reproduce the main characteristics of the curves, there was an evident shift of the maximum RCI to compositions with lower x values, which is an indication of the existence of interactions between phases.…”

Characterization of the magnetic interactions of multiphase magnetocaloric materials using first-order reversal curve analysis

“…4 The general features of these composites can be properly described by considering an interaction-free model. 5 However, a more careful analysis that considers dipolar interactions between phases improves the agreement between experimental results and numerical predictions. 6 Using this analysis, it was possible to predict an interaction field of the order of 4000 Oe between the individual phases of a composite formed by Fe 71.…”

“…6 Using this analysis, it was possible to predict an interaction field of the order of 4000 Oe between the individual phases of a composite formed by Fe 71. 5 Magnetization first-order reversal curve (FORC) method is becoming a more usual technique for determining interactions in multiphase magnetic materials. 7 Initially proposed as a method to identify the Preisach model parameters, 8 it was later extended as a model-independent technique to characterize the irreversibility in magnetic materials magnetization reversal.…”