Half-metallic properties and structural stability of d0-d half-Heusler compounds XYBi (X=K, Rb; Y= Sc, Ti, V, Cr)

Using first-principles electronic structure calculations based on density functional theory, the electronic, magnetic, and structural properties of novel d0-d half-Heusler compounds XYBi (X=K, Rb; Y =Sc, Ti, V, Cr) are investigated. The results indicate that 6 of these compounds, namely, KTiBi, RbTiBi, KVBi, RbVBi, KCrBi and RbCrBi are half-metallic ferromagnets. The half-metallic energy band-gap of these compounds were calculated in the range of 0.46-0.71 eV. A detailed study of the partial density of states showed that the p-d exchange between transition metals 3d and Bi 6p states is mainly responsible for the half-metallic behavior. The total magnetic moments of the compounds under study are in agreement with the Slater-Pauling rule Mtot=Ztot-8 and it is integer valued in a wide range around the equilibrium lattice constant, which indicates that the half-metallic property is not sensitive to the lattice parameter. Employing the structure optimization program USPEX, it is shown that the introduction of d0 alkali metal atom leads to structural stability of the above novel half-Heusler compounds. In the light of their structural stability, high Curie temperature and large half-metallic gap, the above compounds are good candidates for spintronic applications.