Optically Addressable Defect Centers in Magnesium Oxide (MgO)

Oxide materials with wide band gaps, such as magnesium oxide (MgO), can serve as excellent host materials for defect and defect vacancy complexes, potentially providing a platform for next-generation materials for light-matter interactions. Here, we calculate the structural, electronic, magnetic, and optical properties of transition metal defects in the magnesium oxide host consisting of 64 atoms. First, we model the host material and employ hybrid functionals to address the well-known band gap problem inherent in DFT calculations. We also calculate heat of formation, density of states, magnetic moments, and electronic band structures. The defect formation energies are calculated for various transition metals, their vacancy complex versions, as well as native defects of MgO. After identifying possible defects and their charged configurations with singlet/triplet ground/excited states, we calculate the optical properties, such as zero-phonon lines and emission lifetimes for the photoluminescence originating from the transition metal defect states in MgO. We utilize GW calculations for quasi-particle energy levels and constrained DFT for optical properties. Our results indicate that transition metals with d levels within the band gap of this material can be promising candidates for novel quantum applications.