Electronic structure of Mn-doped GeO 2 wide gap semiconductor: a hybrid density functional study

Abstract We explore the effects of Mn substitution on GeO 2 in its bulk rutile structure, using density functional theory with both generalized gradient approximation and the PBE0r hybrid functional. Our objective is to assess the potential emergence of half-metallic (or semiconducting) ferromagnetism. For pure rutile GeO 2 , the experimental wide band gap (4.68 eV) is accurately reproduced by PBE0r using only a small fraction (7%) of the exact exchange. Ordered substitutional bulk alloys Ge 1 − x Mn x O 2 were examined at x = 0.5, 0.25, and 0.17, of Mn concentrations. At x = 0.5, the system is predicted to be a half-metallic ferromagnet with a magnetic moment of 3 µ B per tetragonal unit cell. At lower Mn concentrations ( x = 0.25 and 0.17) the alloys remain semiconducting, with Mn ions in a high-spin configuration. These findings highlight the reliability and efficiency of the PBE0r functional in describing ultra-wide-gap oxides and indicate that Mn-doped GeO 2 bulk systems deserve further theoretical and experimental attention.