The Role of Local Orbital Hybridization in Band Gap Opening and Magnetism Induced by Single-Atom Doping in Graphene

In this study, we employ first-principles density functional theory calculations to investigate the impact of single-atom doping on the electronic band structure of graphene. Our results demonstrate that specific dopants induce a local transition in graphene's hybridization from sp2 to sp3, which plays a crucial role in the opening of the band gap and the emergence of magnetism. We also found that electron-donating dopants cause significant electron localization near the Fermi level, resulting in the formation of nearly flat band states. Furthermore, when a dopant contributes an extra electron to the graphene lattice, the localized flat-band electrons drive band splitting, induce spin polarization, and generate a net spin magnetic moment in the system. These findings offer fundamental insights into how single-atom doping modifies graphene's electronic and magnetic properties, highlighting its potential for spintronic applications and tunable electronic devices.