Influence of the demagnetizing field on the determination of the magnetocaloric effect from magnetization curves

The influence of the demagnetizing factor (N) on the magnetic entropy change (Delta S-M) curves is studied for materials with a second order phase transition. For this purpose, a soft magnetic amorphous ribbon is measured for different orientations of the magnetic field with respect to the plane of the sample. For temperatures below the Curie temperature (T-C), the increase in N causes a decrease in Delta S-M, while for temperatures above T-C no change in the shape of the curves has been found for the different orientations, as expected. In order to eliminate this influence of N and compare the Delta S-M(T) curves for samples with different shapes, the recently proposed universal curve for the magnetocaloric effect can be used. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3067463]