Electronic Properties of Armchair Graphene Nanoribbons under a Perpendicular Magnetic Field

Armchair graphene nanoribbons (AGNRs) provide a promising platform for tailoring graphene's electronic properties through geometrical and external-field control. This work investigates the combined effects of ribbon width and a uniform perpendicular magnetic field on the low-energy electronic structure of AGNRs. A nearest-neighbor tight-binding Hamiltonian incorporating magnetic coupling through Peierls phase factors is employed to calculate the energy dispersions and minimum conduction-band energies of ribbons with Ny = ۱۲۰, ۱۲۱, and ۱۲۲ dimer lines. The results reveal that even a one-dimer-line variation significantly changes the low-energy subbands because of transverse quantum confinement. Increasing the magnetic field shifts the conduction subbands, modifies their curvature, and generally lowers the minimum conduction-band energy. The response is strongly dependent on the ribbon-width family: the ۳p and ۳p+۱ ribbons exhibit a monotonic reduction in minimum conduction energy, whereas the ۳p+۲ ribbon remains nearly metallic throughout the investigated field range. These findings demonstrate that the competition between quantum and magnetic confinement enables effective control of the low-energy spectrum of AGNRs, highlighting their potential for tunable graphene-based electronic and magnetoelectronic devices.

کلیدواژه ها:

Armchair graphene nanoribbons ، tight-binding model ، Peierls phase ، magnetic field ، quantum confinement