Dirac-like half-metallicity of d0−d half-Heusler alloys

Notwithstanding the intuitive chemical bond view that atoms devoid of d electrons are unable to form d−d covalent bond, rigorous density functional band structure calculations indicate that half-Heusler alloys of 3d transition metals and d0 alkali or alkaline-earth metals defined by the valence electronic configuration ns1,2(n−1)d0, can produce all kinds of half-metallic behavior including the elusive Dirac-like half-metallicity that is reported in the prototype d0−d half-Heusler alloy CoKSb such that a sizable gap appears in the minority-spin band structure at the Fermi level, whereas in the majority-spin channel the conduction and the valence bands touch directly at the Γ point and the Fermi level. The linear dispersion of the conduction band and one of the valence bands in the majority-spin channel, indicates that the carriers have vanishingly small band-mass, very high mobilities, and are 100% spin-polarized. This finding is of immense interest for spintronic applications because the Dirac massless fermions-as in graphene-have remarkable properties that are now combined with 100% spin polarization in half-Heusler CoKSb.