Through patterned chemical modification, we show that both graphene sheets and zigzagedged graphene nanoribbons zgnrs can be converted to half metals as long as the unmodified carbon strip or width of zgnrs is sufficiently wide. Firstprinciples study of linedefectembedded zigzag. Gatecontrolled midinfrared light bending with aperiodic. Half metallicity recently predicted in the zigzagedge graphene nanoribbons zgnrs and the hydrogenated carbon nanotubes cnts enables fully spinpolarized electric currents, providing a basis for carbonbased spintronics. Graphene nanoribbons with smooth edges behave as quantum wires xinran wang1,2, yijian ouyang3, liying jiao1, hailiang wang1,limingxie1,justinwu1, jing guo3 and hongjie dai1 graphene nanoribbons with perfect edges are predicted to exhibit interesting electronic and spintronic properties14, notably quantumcon. Dec 15, 2015 researchers have succeeded in experimentally realizing metallic graphene nanoribbons gnrs that are only 5 carbon atoms wide.
Breakdown current density of graphene nanoribbons raghunath murali,a yinxiao yang, kevin brenner, thomas beck, and james d. High quality graphene nanoribbons epitaxially grown on the sidewalls of silicon carbide sic. This behavior is also found to be robust in the presence of disorder. A halfmetal is any substance that acts as a conductor to electrons of one spin orientation, but. Based on firstprinciples calculations, we present the electronic and magnetic properties of a class of line defectembedded zigzag graphene nanoribbons, with one edge saturated by two hydrogen atoms per carbon atom and the other edge terminated by only one hydrogen atom. An effective approach to achieve a spin gapless semiconductorhalfmetalmetal transition in zigzag graphene nanoribbons. Graphene is a oneatomiclayer thick twodimensional material made of carbon atoms arranged in a honeycomb structure. It is experimentally shown that graphene has unusually high thermal conductivity 67. Controlling halfmetallicity of graphene nanoribbons by using. They noted that when doping nanoribbons, edgetype and substitutional doping induce different electronic properties to the systems and, in some cases, half metallic behavior. These magnetic nanoribbons provide potential building blocks for spintronic devices.
Ultranarrow metallic armchair graphene nanoribbons amina kimouche1, mikko m. Yetisene a graphenebased metamaterial lens is theoretically proposed by combining plasmonic nanoribbons with. Using 2dimensional nanosheets in a 3dimensional world webinar. Received 8 december 2015 received in revised form 30 may 2016 accepted 20 june 2016 available online 20 june 2016 keywords. Chemists have been able to manipulate graphene by enhancing its processibility and versatility. Electrical current can be completely spin polarized in a class of materials known as halfmetals, as a result of the coexistence of metallic nature for. This introduction to graphene has been created to impart a general understanding of what graphene is, the types of graphene available, as well as synthesis methods and.
Graphene nanoribbons exfoliated from graphite surface dislocation bands by electrostatic force anton n sidorov1, 23, tanesh bansal,pjouseph1 and gamini sumanasekera1,4 1 department of physics, university of louisville, louisville, ky 40292, usa 2 department of electrical and computer engineering, university of louisville, ky 40208, usa. In particular, graphene ribbons have been predicted to be metallic if their edges exhibit a zigzag morphology, whereas armchair edges can give rise to either semiconducting or metallic transport. Enhanced halfmetallicity in the zigzag graphene nanoribbons by adsorption of the zigzag hydrogen fluoride molecular chains. The spinpolarized electronic structure and half metallicity of zigzag graphene nanoribbons zgnrs with asymmetric edge terminations are investigated by using first principles calculations. Graphene nanoribbons gnrs, also called nano graphene ribbons or nanographite ribbons are strips of graphene with width less than 50 nm. The spinpolarized electronic structure and halfmetallicity of zigzag graphene nanoribbons zgnrs with asymmetric edge terminations are investigated by using first. Zgnrhalf turns to half metal when it is wider than 12zigzag chains. Halfmetallic behavior arises from the formation of spinsplit dispersive states near the fermi energy, reducing the band gaps compared to the unpolarized case. Robustness halfmetallicity in defective graphene nanoribbons. Nov 16, 2006 here we predict half metallicity in nanometrescale graphene ribbons by using firstprinciples calculations. Using firstprinciples calculations, we investigate the electronic and magnetic properties of zigzag graphene nanoribbons zgnrs supported on hydrogenated. Dec 16, 2015 graphene nanoribbons have been suggested as ideal wires for use in future nanoelectronics. One dangling bond per 17 edge atoms are consid ered, which corresponds to 5.
Unlike the previously proposed scheme that requires unrealistic strong external electric fields, the obtained halfmetallicity with sizeable halfmetallic gap and high energetic stability of magnetic order of. Sofo department of physics and materials research institute penn state alejandro suarez ning shen ajay chaudhari. Halfmetallic graphene nanoribbons, nature 444, 347 2006. 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 property can be controlled by the external electric fields. Efficient synthesis of graphene nanoribbons sonochemically cut from graphene sheets zhongshuai wu, wencai ren, libo gao, bilu liu, jinping zhao, and huiming cheng shenyang national laboratory for materials science, institute of metal research, chinese academy of sciences, 72 wenhua road, shenyang 110016, china. Electronic states of graphene nanoribbons and analytical solutions. Using firstprinciples calculations, we investigate the electronic and magnetic properties of zigzag graphene nanoribbons zgnrs supported on hydrogenated and fluorinated zgnrs. Spin polarized calculations are carried out with dft.
Louie1,2 1department of physics, university of california at berkeley, berkeley, california 94720, usa. Graphene nanoribbons have been largely studied theoretically, experimentally and. The af ground state of zsicnrs is intrinsically halfmetallic, with no need of external modulation. Table of contents 1 transport in graphene nanoribbons 2. One of the most recent advancements is the development of graphene nanoribbons gnrs. The coupling between the two edges can be either antiferromagnetic af or ferromagnetic f. 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. The halfmetallicity of zigzag graphene nanoribbons with. Nov 16, 2006 firstprinciples calculations predict that half metallic behaviour can be found in nanometrescale ribbons of graphene, in practically realistic conditions. Energy gaps in graphene nanoribbons youngwoo son,1,2 marvin l. Halfmetallic graphene nanoribbons youngwoo son, 1,2marvin l.
Halfmetallicity in edgemodified zigzag graphene nanoribbons. Periodically functionalized graphene can mimic electronic behavior of edgemodified zgnrs as the edgemodified zigzag carbon chains effectively divide a graphene. Edgestressinduced warping of graphene sheets and nanoribbons v. Enhanced halfmetallicity in edgeoxidized zigzag graphene. Raman spectroscopy in graphene and nanoribbons scientific. Materials design of halfmetallic graphene and graphene. They noted that when doping nanoribbons, edgetype and substitutional doping induce different electronic properties to the systems and, in some cases, halfmetallic behavior. Woods department of physics, university of south florida, 4202 e. Controlling halfmetallicity of graphene nanoribbons by. Prediction of twodimensional materials with halfmetallic dirac cones. The optical conductivity of abstacked bilayer graphene exhibits several interesting infrared features as revealed in recent measurements.
The oxidation schemes considered include hydroxyl, lactone, ketone, and ether groups. Halfmetallicity is also proposed 22 by applying an inplane electric field to modify the natural energy distribution of spins in the ribbon. 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 received 29 june 2006. Halfmetallic dirac cone in zigzag graphene nanoribbons on graphene. Materials for applications, playground for physicists jorge o. What links here related changes upload file special pages permanent link page information wikidata item cite this. Graphene also has unique thermal and mechanical properties. Transport in graphene nanoribbons transport in graphene nanoribbons version. Using electrons more like photons could provide the foundation for a new type of electronic device that would capitalize on the ability of graphene to carry electrons with almost no resistance even at room temperature a property known as ballistic transport. Graphene nanoribbons gnrs have been proven to be unique conjugated polymers.
Here we predict half metallicity in nanometrescale graphene ribbons by using firstprinciples calculations. Electronic properties of lidoped zgnr are investigated. The successful fabrication of single layered graphene has generated a great deal of interest and research into graphene in recent years. Half metallic behavior arises from the formation of spinsplit dispersive states near the fermi energy, reducing the band gaps compared to the unpolarized case. First, a short introduction of graphene crystal structure and phonon dispersion is given. Up to now, halfmetallic property has been found not only in some ferromagnetic metals, such as manganese perovskites 1 and heusler. 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. Facile synthesis of high quality graphene nanoribbons.
Graphene synthesis, properties, and applications cheap tubes. Lithographic4,5,7, chemical811 and sonochemical1,12 methods have been developed to make graphene nanoribbons. Graphene, the atomically thin twodimensional crystal of graphite, has an unusual set of qualities that make it useful for both fundamental research1. Realizing semiconductorhalfmetal transition in zigzag. Intrinsic halfmetallicity in modified graphene nanoribbons. Toward coveedged low band gap graphene nanoribbons journal. Realizing robust halfmetallic transport with chemically.
Graphene nanoribbon based plasmonic fresnel zone plate. The next step in the study of graphene nanoribbons is to grow them with reproducibility. Firstorder and the double resonance raman scattering mechanism in graphene are discussed to understand the most prominent raman peaks. 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. Folded graphene nanoribbons with single and double closed. Graphene nanoribbons gnrs, also called nanographene ribbons or nanographite ribbons are strips of graphene with width less than 50 nm. Photothermoelectric effect of graphene nanoribbon nanodevice walid s. Graphene has been established as one of the strongest materials ever measured 8. Pdf metalterminated graphene nanoribbons researchgate.
Layerselective halfmetallicity in bilayer graphene. Halfmetallicity recently predicted in the zigzagedge graphene nanoribbons zgnrs and the hydrogenated carbon nanotubes cnts enables fully spinpolarized electric currents, providing a basis for carbonbased spintronics. Jun 25, 2009 the geometries, formation energies, and electronic and magnetic properties of ndoping defects, including single atom substitution and pyridine and pyrrolelike substructures in zigzag graphene nanoribbons zgnrs, were investigated by means of spinunrestricted density functional theory computations. Robust band gap and halfmetallicity in graphene with. The mechanical strain serves as the onoff switches for functions of halfmetal and spingapless semiconductor to occur. Periodically functionalized graphene can mimic electronic behavior of edgemodified zgnrs as the edgemodified zigzag carbon chains. Hydrogenation and fluorination provide promising applications for tuning the properties of graphenebased nanomaterials. It is possible to tailor graphene, using covalent or supramolecular chemistry, into a variety of forms. Electronic transport in graphene nanoribbons melinda young han this dissertation examines the electronic properties of lithographically fabricated graphene anoribbons gnrs with widths in the tens of nanometers.
Nanoribbon doping electronic properties dft abstract zigzag graphene nanoribbons zgnrs are known to exhibit metallic behavior. Electronic states of graphene nanoribbons and analytical. Pdf on mar 22, 2011, erjun kan and others published graphene. Gatecontrolled midinfrared light bending with aperiodic graphene nanoribbons array view the table of contents for this issue, or go to the journal homepage for more.
Firstprinciples calculations predict that halfmetallic behaviour can be found in nanometrescale ribbons of graphene, in practically realistic conditions. This includes coupled optical resonators,2 metallic plasmonic structures,3. In their article, the research team demonstrated fabrication of the. Straininduced programmable halfmetal and spingapless. Scalable templated growth of graphene nanoribbons on sic. Graphene ribbons were introduced as a theoretical model by mitsutaka fujita and coauthors to examine.
Electronic properties of lidoped zigzag graphene nanoribbons p. Furthermore, the zgnrs supported on hybrid nanoribbons exhibit the half semiconducting to half metallic behavior transition as the interlayer spacing is gradually reduced, which is realized more easily for the hybrid support with a relatively wide fluorographene moiety compared to its narrow counterpart. Graphene nanoribbons exfoliated from graphite surface. Nano letters bulk production of a new form of sp2 carbon. In contrast to graphene, which is semimetallic with zeroband gap, gnrs are tunable band gap semiconductors and thus attractive materials for nanoscale electronic devices, such as field effect transistors. This results in a single type of spin state at the fermi. Ervasti2, robert drost1, simo halonen3, ari harju2, pekka m. For fe and v atoms, both feld and vld show spinpolarized halfmetallic properties.
Enhanced half metallicity in the zigzag graphene nanoribbons by adsorption of the zigzag hydrogen fluoride molecular chains. We present a comprehensive theoretical study of the electronic properties and relative stabilities of edgeoxidized zigzag graphene nanoribbons. Low temperature and temperaturedependent measurements reveal a length and orientation. Meindl microelectronics research center, georgia institute of technology, atlanta, georgia 30332, usa. Prediction of twodimensional materials with half metallic dirac cones. Electrical current can be completely spin polarized in a class of materials known as halfmetals, as a result of the coexistence of metallic nature for electrons with one spin orientation and insulating nature for electrons with the other.
Zgnr is exhibited half metallic or semiconductor behavior. Tunable phononinduced transparency in bilayer graphene. Molecular dynamics simulation of melting and vacancy. Unlike the previously proposed scheme that requires unrealistic strong external electric fields, the obtained half metallicity with sizeable half metallic gap and high energetic stability of magnetic order of. Efficient synthesis of graphene nanoribbons sonochemically. 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. Layerselective halfmetallicity in bilayer graphene nanoribbons. Its fascinating electrical, optical, and mechanical properties ignited enormous interdisciplinary interest from the physics, chemistry, and materials science fields. Electronic properties of lidoped zigzag graphene nanoribbons. Graphene nanoribbon based plasmonic fresnel zone plate lenses sunan deng,a haider butt,a kyle jiang,a bruno dlubak,b piran r.
Ballistic tracks in graphene nanoribbons dtu orbit. Kidambi,c pierre seneor,b stephane xavierd and ali k. 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. Our results highlight the possibilities of using triangular perforations in graphene to open electronic band gaps.
Graphene ribbons were introduced as a theoretical model by mitsutaka fujita and coauthors to examine the edge and nanoscale size effect in graphene. After having worked at the ibm watson research center, bell laboratories, and university of pennsylvania, he joined the uc berkeley faculty in 1980. The existence of curious materials called half metals is predicted. The relatively high yield synthesis of pristine graphene nanoribbons will make these materials easily accessible for a wide range of fundamental and practical applications. Zgnrs become halfmetallic when an external transverse. Spintronic transport in armchair graphene nanoribbon with. Half metal phase in the zigzag phosphorene nanoribbon nature. Ballistic transport in graphene suggests new type of. Halfmetallic materials are characterized by the coexistence of metallic behaviour for. Realizing semiconductorhalfmetal transition in zigzag graphene. Robustness of half metallicity in defective graphene nanoribbons. Zhang2,4 1division of engineering, brown university, providence, rhode island 02912, usa 2institute of high performance computing, singapore 8632 3program in applied and computational mathematics, princeton university, princeton.
Files available from the acs website may be downloaded for personal use only. 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 10. Here we predict halfmetallicity in nanometrescale graphene ribbons by using firstprinciples calculations. The edge carbon atoms are more easily substituted with n atoms, and threenitrogen vacancy. Growth of graphene nanoribbons up to this point graphene nanoribbons have been grown through chemical, sonochemical and lithographic methods. Electrical current can be completely spin polarized in a class of materials known as halfmetals, as a result of the coexistence of. Tunable phononinduced transparency in bilayer graphene nanoribbons. After its successful experimental realization,1 graphene nanoribbon gnr becomes an important candidate for.
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