Pairwise chemical interactions of charged transition-metal impurities in insulators

Abstract

We report the pairwise chemical interaction and the direct $d\ensuremath{-}d$ interactions of substitutional $3d$ transition-metal impurities in various insulator hosts for various charged conditions by first-principles calculations. Our calculations show that for nearest-neighbor impurity pairs, the direct $d\ensuremath{-}d$ interactions play an important role in the binding of the impurities and the degree of these interactions increases as the defect charge state is varied from positive to negative. This allows for direct control of the transition-metal impurity clustering and possible secondary phase formation by $n$- or $p$-type doping.