Halfmetallic graphene nanoribbons youngwoo son, 1,2marvin l. Under a transverse electric field, zigzagedge graphene nanoribbon transforms to an antiferomagnetic half metal 21 5,6,8,9, their zigzagedge nanoribbons are metals with half metallic ground. Synthetic engineering of graphene nanoribbons with. Six chemical functional groups, namely, oh, nh2, nch32, so2, no2, and cn, are considered for the edge modification. From nanographene and graphene nanoribbons to graphene. Elements s4 e25 why scientists used graphene nanoribbons to engineer bionic mushrooms. From nanographene and graphene nanoribbons to graphene sheets. Graphene nanoribbons can also be either metallic or semiconducting depending on the crystallographic direction of. Gnrs have been suggested as ideal materials for nanoelectronics, where wiring is reduced to the atomic scale. Although many chemical modification schemes for achieving half metallicity in zigzagedged graphene nanoribbons zgnrs have been proposed, practically, half metallic transport is hardly observable with them due to the resulting negligible energy difference of the antiferromagnetic af and ferromagnetic f configurations between the two edges. Here we predict halfmetallicity in nanometrescale graphene ribbons by using firstprinciples calculations. A new synthetic strategy toward novel linear twodimensional graphene nanoribbons up to 12 nm has been established. Graphene ribbons were introduced as a theoretical model by mitsutaka fujita and coauthors to examine the edge and nanoscale size effect in graphene.
Algraphene nanocomposites wang with coworkers 21 fabricated algraphene nanocomposites showing a dramatic enhancement in strength, as compared to their graphene free counterpart. Graphene nanoribbons on highly porous 3d graphene for high. Graphene is a oneatomiclayer thick twodimensional material made of carbon atoms arranged in a honeycomb structure. The graphitic structures form a 3d epitaxial structure with the lattice of the metal and bond with atoms in the metal making the. Graphene nanoribbons gnr also called nanographite ribbons carbon based material onedimensional structures with hexagonal two dimensional carbon lattices a derivative of graphene graphene ribbons were introduced as a theoretical model by mitsutaka fujita 9. Electrochemical properties of graphene oxide nanoribbons.
When graphene nanoribbons are bent, inhomogenous strains are created that lead to a spinsplitting of the electronic states, which gives rise to half metallicity. More important, edge oxidation is found to lower the onset electric field required to induce halfmetallic behavior and extend the overall field range at which the systems remain halfmetallic. Although many chemical modification schemes for achieving halfmetallicity in zigzagedged graphene nanoribbons zgnrs have been proposed, practically, halfmetallic transport is hardly observable with them due to the resulting negligible energy difference of the antiferromagnetic af and ferromagnetic f configurations between the two edges. Electrical current can be completely spin polarized in a class of materials known as half metals, as a result of the coexistence of metallic nature for. Inhomogeneous straininduced halfmetallicity in bent. Introduction to graphenebased nanomaterials can be read in many ways and you are encouraged to make your own path through the book. In this issue of chem, rubin and coworkers report a new way of synthesizing graphene nanoribbons by combining the advantages of straightforward organic synthesis, intelligent crystal engineering, and highyielding solidstate transformations. The gnrs created by the team at aalto, described in the journal nature communications science.
So we further investigate the variation of the states in the d 2 2 the states in the spin down channels around the fermi level are divided into four subbands, marked by 1, 2, 3 and 4 see fig. Get the latest science news with sciencedaily s free. Researchers have succeeded in experimentally realizing metallic graphene nanoribbons gnrs that are only 5 carbon atoms wide. Lithographic4,5,7, chemical811 and sonochemical1,12 methods have been developed to make graphene nanoribbons. We show that this phenomenon is realizable if inplane homogeneous electric fields are applied across the zigzagshaped edges of the graphene nanoribbons, and that their magnetic properties can be controlled by the external electric fields. A new templated growth technique for fabricating nanoribbons of epitaxial graphene has produced structures just 15 to 40 nanometers wide that conduct current with. Materials design of halfmetallic graphene and graphene nanoribbons. Metallized dna nanolithography for encoding and transferring spatial information for graphene patterning zhong jin1, wei sun2,3, yonggang ke2, chihjen shih1, geraldine l. Nano letters enhanced halfmetallicity in edgeoxidized. Utilizing these characters of the topological states, we develop a novel agnr superlattice that possesses two zigzag edges per unit cell. Once the halfmetallic state is reached, further increase. We use electrocharging assisted process which creates graphene nanoribbons and nanosheets in a metal by the application of a high dc current of 150 a to a mixture of the liquid metal and particles of carbon.
Strano1 the vision for graphene and other twodimensional electronics is the direct production of. Particular attention is placed on the possibility of achieving halfmetallicity in the graphene nanostructures. It has been accepted for inclusion in xiao cheng zeng. Through patterned chemical modification, we show that both graphene sheets and zigzagedged graphene nanoribbons zgnrs can be converted to halfmetals as long as the unmodified carbon strip or width of zgnrs is sufficiently wide. Introduction to graphenebased nanomaterials additional. Materials design of halfmetallic graphene and graphene. In this work, graphene oxide nanoribbons gonrs were synthesized by unzipping. Networks of graphene nanoribbons and nanosheets formed in. Various microscopic studies of these novel structures showed a high tendency to selfassemble. Graphene nanoribbons have been suggested as ideal wires for use in future nanoelectronics. Twodimensional graphene nanoribbons journal of the. Realizing robust halfmetallic transport with chemically modi. Electronic transport in graphene nanoribbons melinda young han this dissertation examines the electronic properties of lithographically fabricated graphene \nanoribbons gnrs with widths in the tens of nanometers.
Synthesis and application of graphene and graphene. In this exercise you will get some handson experience on the electronic structure of. Louie1,2 1department of physics, university of california at berkeley, berkeley, california 94720, usa 2materials sciences division, lawrence berkeley national laboratory, berkeley, california 94720, usa dated. Chemical functionalization of graphene nanoribbons. A theoretical study of graphene nanoribbons youtube. The existence of curious materials called half metals is predicted. The nanoribbons are characterized by ms, uvvis, and scanning tunneling microscopy stm.
The successful fabrication of single layered graphene has generated a great deal of interest and research into graphene in recent years. University of california at berkeley and lawrence berkeley national lab. Chigrin institute of highfrequency and communication technology faculty of electrical, information and media engineering. Doping of graphene and graphene nanoribbons is relevant because, depending on the location of the dopants and their concentration, their physicochemical properties could be tuned and controlled. Periodically functionalized graphene can mimic electronic behavior of edgemodified zgnrs as the edgemodified zigzag carbon chains effectively divide a. In addition, elastic strains in graphene nanoribbons dramatically affect their electronic properties and thereby can be used in design. A systematic study of various edge modified graphene nanoribbons gnrs have been performed using a density functional theory method. Realizing robust halfmetallic transport with chemically. Get the most important science stories of the day, free in your inbox. The relatively high yield synthesis of pristine graphene nanoribbons will make these materials easily accessible for a wide range of fundamental and practical applications. Intrinsic halfmetallicity in modified graphene nanoribbons. Over the past decade, the bottomup synthesis of structurally defined graphene nanoribbons gnrs with various topologies has attracted significant attention due to the extraordinary optical, electronic, and magnetic properties of gnrs, rendering them suitable for a wide range of potential applications e. Pdf chemical functionalization of graphene nanoribbons. Its fascinating electrical, optical, and mechanical properties ignited enormous interdisciplinary interest from the physics, chemistry, and materials science fields.
Researchers from aalto university in finland have developed graphene nanoribbons gnrs that exhibit metallic properties and could be used in future electronic devices. We explore the electronic properties of finitelength graphene nanoribbons as well as graphene nanodisks with various sizes and shapes in quest of metallic ones. Synthesis and application of graphene and graphene nanoribbons shintaro sato fujitsu laboratories ltd. Electronic structure and stability of semiconducting. We further show using first principle calculations that, by modifying the geometry of such gnrs, it is possible to get metallic gnrs with tunable bandwidth. Exploration of half metallicity in edgemodified graphene. Graphene is a highly studied material due to its unique electrical, optical, and mechanical properties. The first two subbands 1 and 2 belong to the conduction band while the other two 3 and. Templated growth technique produces graphene nanoribbons. One of the most recent advancements is the development of graphene nanoribbons gnrs layers of graphene with ultrathin width of. The properties of graphene can be further improved by making nanocomposites with conducting polymers. Graphene nanoribbons get metallic aalto university. Graphene nanoribbons on highly porous 3d graphene foam as the binder. Facile synthesis of high quality graphene nanoribbons.
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