Theory of Electro-Optical Properties of Graphene Nanoribbons

We present calculations of the optical absorption and electro-absorption spectra of graphene nanoribbons (GNRs) using a $\pi -$electron approach, incorporating long-range Coulomb interactions within the Pariser-Parr-Pople (PPP) model Hamiltonian. The approach is carefully bench marked by computing quantities such as the band structure, electric-field driven half metallicity, and linear optical absorption spectra of GNRs of various types, and the results are in good agreement with those obtained using\emph{ab initio} calculations. Our predictions on the linear absorption spectra for the transversely polarized photons provide a means to characterize GNRs by optical probes. We also compute the electro-absorption spectra of the zigzag GNRs, and argue that it can be used to determine, whether or not, they have a magnetic ground state, thereby allowing the edge magnetism to be probed through non-magnetic experiments.