ACTA

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

J. Kamarád^a, J. Kaštil^b, Z. Arnold^a, P. Javorský^b and V. Sechovský^b
^aInstitute of Physics ASCR, v.v.i., Na Slovance 2, 182 21 Praha 8, Czech Republic
^bCharles University in Prague, Faculty of Mathematics and Physics, Ke Karlovu 3, 121 16 Praha 2, Czech Republic

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The results of direct measurements of the magneto-caloric characteristics Δ T_ad and the indirect determination of Δ S_m of pure Gd around the Curie temperature and of the FeMnP_0.45As_0.55 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 FeMnP_0.45As_0.55 in the role of a refrigerant is discussed.

DOI: 10.12693/APhysPolA.118.1000
PACS numbers: 75.30.Sg, 75.30.Kz, 75.50.Cc