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 Co₂CrAl 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 Co₂CrAl alloy is half-metallic. On the other hand, the half-metallic properties are not observed in the electronic structures of Co₂FeAl. The composition dependence of electronic structures of Co₂(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.