The isothermal variation of the entropy (ΔST) may be miscalculated from magnetization isotherms in some cases: MnAs and Gd5Ge2Si2 compounds as examples

The determination of the isothermal variation of the entropy (Delta S-T) is discussed in the present work We show that Delta S-T has very different profiles and magnitudes when calculated from M vs. H or M vs. T experimental data. For MnAs compound, Delta S-T A obtained from M vs. T data does not present a colossal peak This result and the agreement between theoretical and experimental non-colossal magnetocaloric effect indicate that the colossal peak may be miscalculated from M vs. H experimental data. For Gd5Ge2Si2 compound, Delta S-T obtained from M vs. T data does not present the peak observed in Delta S-T from M vs. H data. (c) 2011 Elsevier B.V. All rights reserved.