Ab initio prediction of half-metallic properties for the ferromagnetic Heusler alloys Co₂MSi (M=Ti, V, Cr)

By means of density functional calculations the magnetic and electronic properties and phase stabilities of the Heusler compounds Co$_2$MSi (with M=Ti, V, Cr, Mn, Fe, Co, Ni) were investigated. Based on the calculated results we predict the ferromagnetic phases of the compounds Co$_2$TiSi, Co$_2$VSi and Co$_2$CrSi to be half-metals. Of particular interest is Co$_2$CrSi because of its high density of majority spin states at Fermi energy in combination with a reasonably high estimated Curie temperature of 747K. The compounds Co$_2$TiSi and Co$_2$VSi are thermodynamically stable, whereas Co$_2$CrSi is a metastable phase which might be stabilized by suitable experimental techniques.