Magnetic properties of half-metallic semi Heusler Co1−xCuxMnSb compounds

A study of the half-metallic character of the semi Heusler alloys Co1−xCuxMnSb (0⩽x⩽0.9) is presented. We investigated the saturation magnetization MS at temperatures from 5 K to room temperature and the temperature dependence of the DC magnetic susceptibility χ above Curie temperature TC. The magnetic moments at 5 K, for most compositions are very close to the quantized value of 4 μB for Mn3+ ion, the compound with 90% Co substituted by Cu is still ferromagnetic with MS (5 K)=3.78 μB/f.u. These results emphasize the role of Co atoms in maintaining the ferromagnetic order in the material. The Curie temperature is decreased from 476 K to about 300 K as the Cu content increases from 0% to 90%. Above TC, the χ−1 vs T curves follow very well the Curie–Weiss law. The effective moment μeff and paramagnetic Curie temperature θ are derived. A comparison between the values of MS at 5 K and μeff shows a transition from localized to itinerant spin system in these compounds.