Abstract
The dynamical properties of polarons in armchair graphene nanoribbons (GNR) is numerically investigated in the framework of a two-dimensional tight-binding model that considers spin-orbit (SO) coupling and electron-lattice (e-l) interactions. Within this physical picture, novel polaron properties with no counterparts to results obtained from conventional tight-binding models are obtained. Our findings show that, depending on the system’s width, the presence of SO coupling changes the polaron’s charge localization giving rise to different degrees of stability for the charge carrier. For instance, the joint action of SO coupling and e-l interactions could promote a slight increase on the charge concentration in the center of the lattice deformation associated to the polaron. As a straightforward consequence, this process of increasing stability would lead to a depreciation in the polaron’s motion by decreasing its saturation velocity. Our finds are in good agreement with recent experimental investigations for the charge localization in GNR, mostly when it comes to the influence of SO coupling. Moreover, the contributions reported here provide a reliable method for future works to evaluate spin-orbit influence on the performance of graphene nanoribbons.
Highlights
Some relevant experimental results have investigated the electronic structure of graphene edges[17] and nanoribbons[18] with particular interest at describing the charge localization signatures
Because the nanoribbon from this figure is a representative of the 3p family, which is known to be of semiconducting nature[10,11], in both cases we observe a localization of the charge carrier
In order to verify this possibility, we investigate the dynamics of charge carriers on an armchair GNR (AGNR)-7 chain, for which we have seen that the initial static solution is highly dependent on considering or not such coupling
Summary
Some relevant experimental results have investigated the electronic structure of graphene edges[17] and nanoribbons[18] with particular interest at describing the charge localization signatures. Yang and coworkers have studied the quantum interferences at different edge structures – irregular armchair, mixed armchair and zigzag, and regular armchair – of a graphene sheet by using atomic-scale scanning tunneling microscopy (STM) topographies[17]. They have observed that quantum interferences form high electronic density of states patterns along the carbon-carbon bonds, whose shapes depend strictly on the edge structure and not on the electron energy. By means of STM measurements, Huang and colleagues have investigated the electronic structure of armchair GNR (AGNR) upon deposition on silver substrates[18] Their results revealed one-dimensional delocalized striped patterns for the electronic density of states in such a way that the electronic charge is distributed along the nanoribbon length. The present study is aimed to provide a deep physical understanding about the configuration of charge carriers in GNR and, the impact of these properties on the charge transport mechanism in these systems
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