Absorption spectra of graphene nanoribbons in external electric and magnetic fields

We investigated the electronic and optical properties of nanoribbons (GNRs) subject to in-plane transverse electric and perpendicular magnetic fields. The numerical calculations were carried out within the generalized multiorbital tight-binding model based on a Hamiltonian which takes into account hopping integrals among the (s,p_x,p_y, and p_z) atomic orbitals. The band structure consists of π bands arising from the p_z orbital and σ bands originating from the (s,p_x, and p_y) orbitals. We found that the energy bands and optical spectra of GNRs can be manipulated efficiently by the edge configuration, armchair or zigzag, and the strength of the external fields. The optical absorption spectra are enriched by exotic characteristics of band structure such as band gap, flat bands, band splitting, shifted of Fermi level, and magnetic quantization. With the rich and unique properties, GNRs are suitable candidates for applications in the fields of photodetectors, nanoelectronics, and spintronics. Our theoretical prediction could be verified by angle-resolved photoemission spectroscopies and optical spectroscopies.