Electronic band structure and magnetism of CoFeV0.5Mn0.5Si

Abstract

Half-metallic Heusler alloys have attracted much attention due to their potential application in spin-transport-based devices. We have synthesized one such alloy, CoFeV0.5Mn0.5Si, using arc melting and high-vacuum annealing. The vacuum annealing was done at 600oC for 24 hours. First principles calculation indicates that CoFeV0.5Mn0.5Si shows nearly half-metallic band structure with the degree of spin polarization of about 93%. The room temperature x-ray diffraction patterns are indexed with the cubic crystal structure without disorder and secondary phases. The annealed sample show ferromagnetic order with the Curie temperature well above room temperature (Tc = 657 K) and the high-field (3T) magnetization at room temperature of about 83 emu/g. Figure 1 below shows the magnetization as a function of temperature of CoFeV0.5Mn0.5Si measured at 1 kOe which shows a smooth magnetic transition at the Curie temperature. The observed structural and magnetic properties are consistent with the theoretical results and these results indicate that CoFeV0.5Mn0.5Si has a potential for room temperature spin-transport-based devices.This research is supported by the National Science Foundation (NSF) under Grant Numbers 2003828 and 2003856 via DMR and EPSCoR.  Figure 1: Thermomagnetic curve M(T) of CoFeV0.5Mn0.5Si alloy. The inset shows the dM/dT versus T curve