Magnetocaloric Effect in Materials with the First Order Transitions - Direct Measurements

Abstract

The results of direct measurements of the magneto-caloric characteristics ∆Tad and the indirect determination of ∆Sm of pure Gd around the Curie temperature and of the FeMnP0.45As0.55 and Ni45Co5Mn31Ga19 intermetallics in the vicinity of the first order magnetic and structural phase transitions are presented and discussed. A pronounced temperature and field dependence of the first order transitions in the studied materials manifests restrictions applying these materials in magnetic refrigeration techniques. An effective use of the Ericsson and the Brayton refrigeration cycles with FeMnP0.45As0.55 in the role of a refrigerant is discussed.