Appearance of half-metallicity in the quaternary Heusler alloys

I report systematic first-principles calculations of the quaternary Heusler alloys, e.g. Co 2 [Cr 1− x Mn x ]Al, Co 2 Mn[Al 1− x Sn x ] and [Fe 1− x Co x ] 2 MnAl. I show that these alloys are also half-ferromagnets when the normal Heusler compounds corresponding to concentration values of zero and unity are half-metals. Moreover, the total spin moment M t in μ B scales linearly with the total number of valence electrons Z t (and thus with the concentration x ) following the relation M t = Z t −24, independently of the origin of the extra valence electrons, confirming the Slater–Pauling behaviour of the normal Heusler alloys. These results pave the way for experimentalists searching for new half-metallic alloys.