Properties of magnetocaloric materials with a distribution of Curie temperatures

The magnetocaloric properties of inhomogeneous ferromagnets that contain distributions of Curie temperatures are considered as a function of the width of such a distribution. Assuming a normal distribution of the Curie temperature, the average adiabatic temperature change, Delta T-ad, the isothermal magnetic entropy change, As, and the heat capacity, c(p), in zero magnetic field and an applied magnetic field of mu H-0 = 1 T, have been calculated using the mean field model of ferromagnetism. Interestingly, both the peak position and amplitude of each of these parameters vary differently with the width of the distribution, explaining the observed mismatch of peak temperatures reported in experiments. Also, the field dependence of Delta T-ad and As is found to depend on the width of the distribution. (C) 2011 Elsevier B.V. All rights reserved.