Abstract
The alkali-adsorbed graphene nanoribbons exhibit the feature-rich electronic and magnetic properties. From the first-principles calculations, there are only few adatom-dominated conduction bands, and the other conduction and valence bands are caused by carbon atoms. A lot of free electrons are revealed in the occupied alkali- and carbon-dependent conduction bands. Energy bands are sensitive to the concentration, distribution and kind of adatom and the edge structure, while the total linear free carrier density only relies on the first one. These mainly arise from a single s − 2pz orbital hybridization in the adatom-carbon bond. Specifically, zigzag systems can present the anti-ferromagnetic ordering across two edges, ferromagnetic ordering along one edge and non-magnetism, being reflected in the edge-localized energy bands with or without spin splitting. The diverse energy dispersions contribute many special peaks in density of states. The critical chemical bonding and the distinct spin configuration could be verified from the experimental measurements.
Highlights
The graphene-based systems, which are formed by the planar sp[2] bondings of carbon atoms, include layered graphites[1, 2], few- and multi-layer graphenes[3, 4], one-dimensional graphene nanoribbons (1D GNRs)[5, 6] and 1D carbon nanotubes (CNTs)[7, 8]
The critical chemical bondings could be analyzed from the atom-dominated energy bands, the spatial charge distribution, and the orbital-projected density of states (DOS)
The predicted main features in energy bands and DOS could be examined by angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling spectroscopy (STS), respectively
Summary
The graphene-based systems, which are formed by the planar sp[2] bondings of carbon atoms, include layered graphites[1, 2], few- and multi-layer graphenes[3, 4], one-dimensional graphene nanoribbons (1D GNRs)[5, 6] and 1D carbon nanotubes (CNTs)[7, 8]. There are some theoretical[64,65,66] and experimental[43, 44] studies on the atom, molecule and polymer adsorptions on the planar GNRs. The first-principles calculations on the Co/Ni-adsorbed GNRs show the spin-split energy bands with the metallic behavior[64]. The critical orbital hybridization in the alkali-carbon bonds responsible for the creation of conduction electrons, the relations between the free carrier density and the kind, distribution and concentration of adatom, and the dependence of electronic and magnetic properties on the edge structure, width and adatom position are worthy of a detailed examination. The predicted main features in energy bands and DOS could be examined by angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling spectroscopy (STS), respectively These rich fundamental features in alkali-adsorbed GNRs are expected to provide potential materials applications in electronic[15, 56] and spintronic[57] devices
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