Electronic and magnetic properties of the (1Â 1Â 1) surfaces of NiMnSb

Using an ab initio electronic structure method, I study the (1 1 1) surfaces of the half-metallic NiMnSb alloy. In all cases there is a very pronounced surface state within the minority gap which destroys the half-metallicity. This state survives for several atomic layers below the surface contrary to the (0 0 1) surfaces where surface states were located only at the surface layer. The lower dimensionality of the surface leads in general to large enhancements of the surface spin moments.