Electronic Transport in Oxidized Zigzag Graphene Nanoribbons
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Electronic Transport in Oxidized Zigzag Graphene Nanoribbons Venkata Sai Pavan Choudary Kolli1, Vipin Kumar1, Shobha Shukla1 and Sumit Saxena1 1 Nanostructures Engineering and Modeling Laboratory, Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai, MH, India - 400076 ABSTRACT The electronic and transport properties of graphene nanoribbons strongly depends on different types of adatoms. Oxygen as adatom on graphene is expected to resemble oxidized graphene sheets and enable in understanding their transport properties. Here, we report the transport properties of oxygen adsorbed zigzag edge saturated graphene nanoribbon. It is interesting to note that increasing the number of oxygen adatoms on graphene sheets lift the spin degeneracy as observed in the transmission profile of graphene nanoribbons. The relative orientation of the oxygen atom on the graphene basal plane is detrimental to flow of spin current in the nanoribbon. INTRODUCTION Graphene is an atomic monolayer of carbon atoms arranged in a honeycomb lattice [1]. This discovery has led to further exploration of other elemental two dimensional materials such as silicene, germanene [2] and stanene [3, 4].Being a zero gap semiconductor, it cannot be used as a viable semiconductor for industrial purposes. Successful efforts have been made to open band gap in the electronic spectrum of graphene [5, 6]. The laterally constrictedgraphene nanoribbons (GNRs) lead to opening of a gap due to confinement effects. Such GNRs have been synthesized using various techniques [7-11] andideally characterized by their edge, which may be zigzag or armchair[12]. The electronic and transport properties of GNRs are very sensitive to these edge states. The spin dependent transport properties of GNRs are widely discussed in the literature. The spin transport properties get dramatically affected in presence of external effects such as doping, edge functionalization, defects and presence of adatoms. The effect of different adatoms has been studied on electronic properties of zigzag and armchair GNRs [13-17]. Recently, the effect of different single adatoms on electron transport in functionalized armchair GNR has been reported [18]. Oxidized graphene sheets comprises of a basal plane of graphene decorated largely by epoxy oxygen atom [19, 20]. Experimental studies of single and multilayers of graphene oxide (GO) suggest that their electronic transport properties are at least two orders of magnitude lesser than that of graphene. Further investigation of these systems is warranted to develop fundamental understanding of the electronic properties of GO. In this manuscript, we try to understand and evaluate, using first principles methods, the transport properties of oxidized GNRs. Systematic studies have been performed to understand effect of increasing oxygen adatoms on GNRs.Our results suggest that as the concentration of oxygen adatom concentration increases, the degeneracy in the spin conductance is lifted and the relative orientati
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