Atomic disorder effects on half-metallicity of the full-Heusler alloys Co₂(Cr_1-xFe_x)A1: A first-principles study

We investigate the atomic disorder effects on the half-metallicity of the full-Heusler alloy Co₂(Cr_1-xFe_x)A1 from first principles by using the Korringa-Kohn-Rostoker method with the coherent potential approximation. Our results show that disorder between Cr and Al does not significantly reduce the spin polarization of the parent alloy Co ₂CrA1, while disorder between Co and Cr makes a considerable reduction of the spin polarization. It is observed that the spin polarization of Co₂(Cr_1-xFe_x)A1 decreases with increasing Fe concentration x in both the ordered L2₁ and the disordered B2 structures, and that the effects of the disorder on the spin polarization is significant at low Fe concentrations. The results suggest that a highly spin-polarized ferromagnet with high Curie temperature will be obtained if a Co₂(Cr_1-xFe_x)A1 with the ordered L2 ₁ structure can be fabricated at low Fe concentrations.