Electronic and magnetic properties of graphene-fluorographene nanoribbons: Controllable semiconductor-metal transition

We investigate the electronic and magnetic properties of graphene channels (2--4 nm wide) embedded within fluorographene, focusing on two distinct interfaces: the fully fluorinated $\ensuremath{\alpha}$ interface and the half-fluorinated $\ensuremath{\beta}$ interface. Density functional theory (DFT) calculations reveal that $\ensuremath{\alpha}\ensuremath{\alpha}$ systems exhibit semiconducting behavior with antiferromagnetic ordering, closely resembling pristine zigzag graphene nanoribbons. In contrast, $\ensuremath{\alpha}\ensuremath{\beta}$ systems display ferromagnetism and a width-dependent semiconductor-to-metal transition. To enable the study of larger systems, we develop and validate effective Hubbard models for both $\ensuremath{\alpha}\ensuremath{\alpha}$ and $\ensuremath{\alpha}\ensuremath{\beta}$ channels. Building upon DFT results and a Wannier function analysis, these models accurately reproduce the electronic structure and magnetic ordering observed in DFT calculations. Crucially, our $\ensuremath{\alpha}\ensuremath{\beta}$ model successfully captures the semiconductor-to-metal transition. Application of this model to larger systems reveals the persistence of a ferromagnetic state with spin polarization localized at the $\ensuremath{\alpha}$ edge. Our results demonstrate the potential of fluorination for targeted property engineering and provide a basis for exploring graphene-fluorographene systems in device applications ranging from microelectronics to spintronics.