Effects of the substitution of Cu for Sn on structural, magnetic and magnetocaloric properties of half-Heusler CoMnSn alloy

Abstract

The structure, magnetic transition and magnetocaloric properties of half-Heusler CoMnSn1-xCux alloy have been investigated. X-ray diffraction reveals that a main phase of hexagonal structure was obtained in alloys, and there is no obvious secondary phase observed in the less doped samples. The impurity phases appear only when the Cu doping level is high, and the amount of impurity phases is less than 0.7 mol.% in the sample x = 0.10. The substitution of Cu for Sn is found to decrease in c/a lattice parameter and cell volume. ZFC and FC measurements show that a magnetic transition from ferromagnetic to paramagnetic phase occurs around 150 K in CoMnSn1-xCux alloy, and the magnetization and Curie temperature of samples can be tuned by the Cu content, in which the magnetization of alloys decreases with the increasing Cu content, while Curie temperature increases by 13 K. The maximum of magnetic entropy change (ΔSM) in a magnetic field change of 5 T is found to be 17.4(2) J/(kg·K) with a large refrigerating capacity of 230.3(8) J/kg for x = 0.02, revealing that CoMnSn1-xCux alloy with the second-order magnetic transition can provide a considerable magnetocaloric effect at a low cost, which suggests a promising candidate for magnetic refrigeration materials.