Electronic structure of Mn-doped GeO2 wide gap semiconductor: a hybrid density functional study.

We explore the effects of Mn substitution on GeO₂in its bulk rutile structure, using density functional theory (DFT) with both GGA and the PBE0r hybrid functional. Our objective is to assess the potential emergence of half-metallic (or semiconducting) ferromagnetism. For pure rutile GeO₂, 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 Ge1-xMnxO₂were examined at x = 0.5, 0.25, and 0.17 of Mn concentrations. At x = 0.5, the bulk system is predicted to be a half-metallic ferromagnet with a magnetic moment of 3 μBper 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 GeO₂bulk systems deserve further theoretical and experimental attention.