Influence of the demagnetizing factor on the magnetocaloric effect: Critical scaling and numerical simulations

In recent years, the magnetocaloric effect is studied not only for the search of potential magnetic refrigerant materials but also for the analysis of critical phenomena. In both cases, the demagnetizing field might have a notable influence on the results. In this work, we carry out a systematic study, based on theoretical simulations, of the influence of the demagnetizing factor on the magnetocaloric properties. On the one hand, we show that demagnetizing factor affects only slightly the magnetic entropy change (ΔSM), reducing its magnitude and shifting the peak to higher temperatures. On the other hand, it dramatically affects the exponent n of field dependence (ΔSM∝Hn) at temperatures below the peak. We demonstrate that scaling of the magnetocaloric curves can be used to remove the influence of the demagnetizing field and, to which extent, critical exponent determination can be affected. Results of numerical simulations are compared with experimental data from a ball milled powder alloy.