Abstract
Incorporation of Mn atoms as magnetic impurities in bulk Si and Ge is of great importance for integrating magnetism with existing device technology. Here, we study the influence of p- and n-type electronic dopants on Mn incorporation in bulk Si and Ge, using first-principles calculations within density functional theory. We find that in Si, the site preference of a single Mn atom is reversed from interstitial to substitutional in the presence of a neighboring n-type dopant (P, As, Sb). In Ge, a Mn atom is more readily incorporated into the lattice when an n-type dopant is present in its immediate neighborhood, forming a stable Mn/dopant pair with both impurities at substitutional sites. A detailed analysis of the magnetic exchange interactions between such pairs reveals a dramatic enhancement in the anisotropy of the magnetic coupling within the systems.