The electronic and magnetic properties of single 3d transition-metal(TM) atom (V, Cr, Mn, Fe, Co, and Ni) adsorbed graphdiyne (GDY) and graphyne (GY) are systematically studied using first-principles calculations within the density functional framework. We find that the adsorption of TM atom not only efficiently modulates the electronic structures of GDY/GY system, but also introduces excellent magnetic properties, such as half-metal and spin-select half-semiconductor. Such modulation originates from the charge transfer between TM adatom and the GDY/GY sheet as well as the electron redistribution of the TM intra-atomic s, p, and d orbitals. Our results indicate that the TM adsorbed GDY/GY are excellent candidates for spintronics.

We propose a new allotrope of graphane, named as tricycle graphane,with a 4up/2down UUUDUD hydrogenation in each hexagonal carbon ring,which is different from previously proposed allotropes with UUDUUD(boat-1) and UUUUDD (boat-2) types of hydrogenation. Its stability and electronic structures are systematically studied using first-principles method. We find that the tricycle graphane is a stable phase in between the previously proposed chair and stirrup allotropes. Its electronic properties are very similar to those of chair, stirrup, boat-1, boat-2, and twist-boat allotropes. The negative Gibbs free energy of tricycle graphane is -91 meV/atom, which very close to that of the most stable chair one (-103 meV/atom). Thus, this new two-dimensional hydrocarbon may be produced in the process of graphene hydrogenation with a relative high probability compared to other conformers.Comment: 5 pages, 3 figure

The transport properties of hybrid nanoribbons formed by partially substituting zigzag boron nitride (graphene) nanoribbons into zigzag graphene (boron nitride) nanoribbons are investigated using the first-principles nonequilibrium Green’s function method. The transport properties are highly improved with the transmission conductance around the Fermi level increasing to 3G 0 in hybrid systems based on zigzag graphene nanoribbons and to 2G 0 in hybrid systems based on zigzag boron nitride nanoribbons. The enhancement is attributed to the coupling effect between B (N) atoms and C atoms at the interface of hybrid systems, which introduces a pair of bonding and antibonding bands around the Fermi level. The transport enhancement also remains in hybrid nanoribbons sandwiched into gold electrodes. The currents of such devices are improved compared with those of pristine ones, which originate from the additional transport channels at the C–B interface.

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The transport properties of the junction assembled by zigzag graphene nanoribbons (ZGNRs) and Au electrode (Au/ZGNR) are investigated using first‐principles calculations. It is found that the Au/ZGNR junction behaves as a typical diode with Schottky barrier at the contact. Our results indicate that although the oxidization at the contact slightly influences the Schottky barrier, the I –V characteristic is effectively modulated. Such effect derives from the impact of the oxidization on the coupling between the ZGNRs and Au electrode. Au/ZGNR junction oxidized by C=O groups at the contact and relative I –V curves. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)