Appearance of half-metallicity in the quaternary Hensler alloys

I report systematic first-principles calculations of the quaternary Heusler alloys, e.g. Co-2[Cr1-xMnx]Al, Co2Mn[Al1-xSnx] and [Fe(1-x)Cox(]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 mu(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.