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

TL;DR

This study explores how fluorination affects the electronic and magnetic properties of graphene nanoribbons, revealing controllable semiconductor-metal transitions and magnetic states, with validated models enabling larger system analysis for device applications.

Contribution

The paper develops and validates effective Hubbard models based on DFT and Wannier functions to accurately simulate electronic and magnetic properties of fluorographene nanoribbons, including the semiconductor-metal transition.

Findings

$eta$ interfaces exhibit ferromagnetism and a width-dependent transition.

$eta$ systems show a controllable semiconductor-to-metal transition.

Models accurately reproduce DFT results and predict properties in larger systems.

Abstract

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 $\alpha$ interface and the half-fluorinated $\beta$ interface. Density functional theory (DFT) calculations reveal that $\alpha\alpha$ systems exhibit semiconducting behavior with antiferromagnetic ordering, closely resembling pristine zigzag graphene nanoribbons. In contrast, $\alpha\beta$ 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 $\alpha\alpha$ and $\alpha\beta$ 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 $\alpha\beta$ 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 $\alpha$ 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.