Theoretical predict of half-metals in Co-Cr-Fe-Al alloys

Abstract

To theoretically examine the existence of half-metals in Co-Cr-Fe-Al alloys, band calculations were carried out for these alloys. Seeing energy dispersion curves E(k) of Co 2CrAl with the Heusler structure, we find that the Fermi level intersects the E(k) curves in the majority-spin state but is located at the energy gap in the minority-spin state, that is, it is predicted that this stoichiometric Co 2CrAl alloy is half-metallic. On the other hand, the half-metallic properties are not observed in the electronic structures of Co 2FeAl. The composition dependence of electronic structures of Co 2(Cr 1-xFe x)Al (x = 1/8-7/8) indicates that the alloys have the tendency to become half-metallic in the range of x < 5/8.