Abstract

In this work, spin-polarized density functional theory (DFT) calculations are employed to investigate the structural, electronic, and magnetic properties of fluorine-adsorbed 7-armchair germanium carbide nanoribbons (7AGeCNRs). Eight stable configurations are identified, all possessing significant negative adsorption energies (up to −5 eV), confirming the high binding affinity of fluorine. Site-dependent structural distortion is observed, where the edge adsorption causes only slight buckling, whereas nonedge adsorption induces strong sp2–sp3 rehybridization and significant ribbon deformation. A key finding is the sharp contrast in magnetic behavior, which correlates with diverse electronic characteristics. Configurations with at least one edge-adsorbed F atom exhibit magnetic moments of 1–2 μ<inf>B</inf>, while purely nonedge configurations remain nonmagnetic (0 μ<inf>B</inf>). Mixed edge–nonedge adsorption reduces magnetization through charge redistribution, with the fully (4F) adsorbed system even showing a small negative magnetic moment (−0.014 μ<inf>B</inf>). Electronic structures further reveal that nonedge fluorination breaks the π-network, producing metallic bands, whereas edge fluorination preserves π-character and leads to half-metallic or ferromagnetic semiconducting states. Orbital- and spin-resolved DOS and charge/spin density analyses confirm that the interplay between F-2p<inf>z</inf> and Ge-/C-p<inf>z</inf> orbitals governs π-network disruption, charge transfer, and spin polarization. These results demonstrate that fluorine distributions and concentrations provide effective control over bandgap, metallicity, and magnetism in GeC nanoribbons, offering valuable guidance for designing tunable GeC nanoribbons-based nanoelectronics and spintronics.