Si: experiment and theory*

Half-metallic Heusler alloys have been investigated as potential materials for spin-transport-based devices. We have synthesized one such material, CoFeV_0.5Mn_0.5Si, using arc melting and high-vacuum annealing at 600^oC for 24 hours. First principles calculation indicates that CoFeV_0.5Mn_0.5Si is nearly half-metallic with the degree of spin polarization of about 93%. The annealed sample exhibits cubic crystal structure without disorder and secondary phases. It shows  ferromagnetic order at room temperature with  the Curie temperature of  657 K and saturation magnetization of 92 emu/g (3.06 μ_B/f.u). The observed structural and magnetic properties are consistent with the theoretical results. Our results indicate that CoFeV_0.5Mn_0.5Si has a potential for room temperature spin-transport-based devices.