Surface states and surface stability in half-metallic systems: the cases of zinc-blende-structure MnSb {111}A, {111}B and {001}.

The surface properties of half-metallic materials can have a profound impact upon their possible utility for spintronic devices, and are therefore of significant interest. Here, we present the results of comprehensive density functional calculations for the {111}A, {111}B and {001} surfaces of the half-metallic zinc-blende phase of MnSb. We predict trimerized and dimerized reconstructions to be favourable whenever geometrically feasible, and our thermodynamic analysis strongly suggests termination with an Sb layer in all the cases studied. The electronic band-structure of the reconstructed Sb-terminated {001} surface is found to retain its half-metallicity, whereas the unfavourable Mn-terminated surface does not. The reconstructed Sb-terminated {111}A and {111}B surfaces are likewise half-metallic, and again the unfavourable Mn-terminated surfaces are not.