Electronic and magnetic properties of Fe2-xCoxTiGe (x=0, 0.5, 1, 1.5, 2) full Heusler alloys

Half metallic and magnetic properties of Fe2TiGe and Co2TiGe full Heusler alloys are studied. The structural stability between the two possible structures, namely, L2(1) (Cu2MnAl phase) and XA (Hg2CuTi phase) structures is analyzed. It is found that L2(1) phase is the stable phase for these alloys. The density of states predicted that Fe2TiGe is a semiconductor and Co2TiGe is half-metallic. When cobalt is substituted for Fe, it is observed that Fe1.5Co0.5TiGe, Fe1.0Co1.0TiGe, Fe0.5Co1.5TiGe alloys exhibit half metallic ferromagnetism with small spin flip gap at the minority spin state. This is due to the presence of d(7) electronic configuration within Co2+ in Fe2+ ions site. Half metallic to metallic phase transition is observed at high pressure. Our work paves the way for designing novel Heusler materials at normal and high pressure. Furthermore, it is observed that Co- doping is an effective strategy to improvise the ferromagnetic performance of Fe2TiGe full Heusler compounds.