An ab initio study of electronic and structural properties of Mn in a GaAs environment

Based on ab initio calculations, we have investigated the atomic geometry, electronic properties and magnetic properties of Mn incorporation in GaAs. The inclusion of the Hubbard potential U in the calculation (namely with the σGGA+U scheme) results in the optimized geometry being contracted by approximately 2% relative to the relaxed geometry obtained by the (σGGA) method. Within both the σGGA and σGGA+U schemes the Mn impurity in bulk GaAs behaves like a d-hole with the majority spin state lying at 0.25 eV above the Fermi level. Theoretically simulated STM images for Mn/GaAs(110) indicate round protrusions at As sites and Ga sites, the latter being dependent on the Mn adsorption site (i.e. in different atomic layers). These results are supportive of a previous experimental STM image obtained with a very low Mn concentration.