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 d(0) alkali or alkaline-earth metals defined by the valence electronic configuration ns(1,2) (n - 1)d(0), can produce all kinds of half-metallic behavior including the elusive Dirac-like half-metallicity that is reported in the prototype d(0) - 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 Gamma 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.