Spin–Orbit Coupling Enhancement in Reversibly Fluorinated Graphene with BN Encapsulation

Fluorination has emerged as an effective approach to induce spin–orbit coupling (SOC) in graphene, yet maintaining high electronic quality remains a significant challenge. Here, we demonstrate reversible fluorination of graphene with subsequent hexagonal boron nitride (h-BN) encapsulation to preserve carrier mobility while enhancing SOC. Controlled fluorination is achieved through optimized CF₄ plasma exposure, and Raman spectroscopy confirms the reversible formation of sp³-type bonds. Low-temperature nonlocal transport measurements reveal enhanced spin Hall signals in fluorinated graphene compared to pristine samples, consistent with SOC-induced spin transport. Encapsulation enables carrier mobilities exceeding ~18,000 cm²/V·s, allowing clear observation of spin-orbit-driven phenomena without significant degradation of coherence. Furthermore, systematic gate-dependent and channel-length-dependent analysis shows evidence of SOC-modulated spin diffusion in the B(-FG-)B heterostructure. Our results highlight reversible chemical modification as a viable route for engineering SOC in high-quality 2D systems, offering new opportunities for gate-tunable spin–orbitronics and topological device platforms based on graphene.