Half-metallic Heusler alloys are of high interest to the material research community due to their potential application in spintronic devices. We have synthesized one such compound, CoFeVGe, using arc melting and high-vacuum annealing at 600oC for 48 hours. The room temperature x-ray diffraction of the sample exhibits a cubic crystal structure without secondary phases. The sample shows a single magnetic transition at its Curie temperature of 249 K, Fig. 1(a). The high field (3T) magnetization measured at 100 K is 41 emu/g. We also observed that the Curie temperature of the sample can be increased to near room temperature with slightly changing the elemental composition. The sample with composition Co1.25Fe0.75VGe remains cubic in crystal structure, and it exhibits a Curie temperature of 294 K and saturation magnetization at 100 K of 36 emu/g. Our first principle calculations of CoFeVGe and Co1.25Fe0.75VGe in their cubic crystal structures predict a high degree of spin polarization of 86% and 82%, respectively. Figure 1(b) shows the calculated element- and spin- resolved density of states for CoFeVGe. These results indicate that Co1.25Fe0.75VGe has a potential for near room temperature spintronic applications.
This research is supported by the National Science Foundation (NSF) under Grant Numbers 2003828 and 2003856 via DMR and EPSCoR.