title: Electronic and optical properties of graphene nanoribbons in external fields.
abstract: A review work is done for the electronic and optical properties of graphene nanoribbons in magnetic, electric, composite, and modulated fields. Effects due to the lateral confinement, curvature, stacking, non-uniform subsystems and hybrid structures are taken into account. The special electronic properties, induced by complex competitions between external fields and geometric structures, include many one-dimensional parabolic subbands, standing waves, peculiar edge-localized states, width- and field-dependent energy gaps, magnetic-quantized quasi-Landau levels, curvature-induced oscillating Landau subbands, crossings and anti-crossings of quasi-Landau levels, coexistence and combination of energy spectra in layered structures, and various peak structures in the density of states. There exist diverse absorption spectra and different selection rules, covering edge-dependent selection rules, magneto-optical selection rule, splitting of the Landau absorption peaks, intragroup and intergroup Landau transitions, as well as coexistence of monolayer-like and bilayer-like Landau absorption spectra. Detailed comparisons are made between the theoretical calculations and experimental measurements. The predicted results, the parabolic subbands, edge-localized states, gap opening and modulation, and spatial distribution of Landau subbands, have been identified by various experimental measurements.
authors.affiliation: Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan. hsienching.chung@gmail.com l28981084@mail.ncku.edu.tw mflin@mail.ncku.edu.tw and Center for Micro/Nano Science and Technology (CMNST), National Cheng Kung University, Tainan 70101, Taiwan.
authors.forename: Hsien-Ching
authors.initials: HC
authors.lastname: Chung
authors.affiliation: Center for General Education, Tainan University of Technology, Tainan 701, Taiwan.
authors.forename: Cheng-Peng
authors.initials: CP
authors.lastname: Chang
authors.affiliation: Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan. hsienching.chung@gmail.com l28981084@mail.ncku.edu.tw mflin@mail.ncku.edu.tw.
authors.forename: Chiun-Yan
authors.initials: CY
authors.lastname: Lin
authors.affiliation: Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan. hsienching.chung@gmail.com l28981084@mail.ncku.edu.tw mflin@mail.ncku.edu.tw.
authors.forename: Ming-Fa
authors.initials: MF
authors.lastname: Lin