Electron mediated/enhanced ferromagnetism in a hydrogen-annealed Mn:Ge magnetic semiconductor

Abstract

We report on the carrier type changes of the p-type for as-grown Mn:Ge films to n-type for post-annealed samples in a hydrogen ambient. The hydrogen-annealed samples exhibit the increased Curie temperature, from 165 to 198 K, and the enhanced magnetic moment, from 0.78 to 1.10 μB/Mn. The first principles calculation using the all-electron full-potential linearized augmented plane wave method indicates that the addition of an electron carrier strengthens the ferromagnetic coupling between the Mn atoms, while the hole carrier caused it to weaken.