Magnetic Correlations in Short and Narrow Graphene Armchair Nanoribbons

Golor, Michael; Koop, C. G.; Lang, Thomas C.; Wessel, Stefan; Schmidt, Manuel

doi:10.1103/physrevlett.111.085504

Cited by 40 publications

(40 citation statements)

References 32 publications

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“…Recently, short GNRs (SGNRs) have received a great deal of attention because they can be fabricated with precise edges by bottom-up method [20][21][22][23][24][25][26][27][28][29][30]. An SGNR has four edges, two of them are armchair edges and the other two are zigzag edges.…”

Section: Introductionmentioning

confidence: 99%

Competition of edge effects on the electronic properties and excitonic effects in short graphene nanoribbons

et al. 2016

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We explore the electronic properties and exciton effects in short graphene nanoribbons (SGNRs), which have two armchair edges and two zigzag edges. Our results show that both of these two types of edges have profound effects on the electronic properties and exciton effects. Both the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) states are alternatively changed between the bulk and the edge states as the lengths of the zigzag edges increase, due to the competition between the states of the two types of edges. The energy gaps, as a function of the lengths of the armchair edges, will then induce two kinds of trends. Furthermore, two kinds of exciton energies and exciton binding energies are found, which can be understood through the two kinds of HOMO and LUMO states in SGNRs. In addition, we find that the three triplet exciton states are not totally energy degenerate in SGNRs due to the spin-polarized states on the zigzag edges.

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Section: Introductionmentioning

confidence: 99%

Competition of edge effects on the electronic properties and excitonic effects in short graphene nanoribbons

et al. 2016

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“…[3][4][5] Recently, the magnetic correlations in finite armchair nanoribbons were studied in detail using an effective low-energy model. 6,7 Thus far, only few observations of this spin-split gap have been reported in large-scale graphene nanoribbons for which the structure of the edge is not known with atomic detail. [8][9][10] Using top-down methods, such as etching two-dimensional graphene or unzipping carbon nanotubes, the preparation of graphene nanoribbons with atomically well-defined edges is challenging.…”

Section: Introductionmentioning

confidence: 99%

Electronic states in finite graphene nanoribbons: Effect of charging and defects

et al. 2013

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Ijäs, M.; Ervasti, M.; Uppstu, Christer; Liljeroth, Peter; van der Lit, J.; Swart, I.; Harju, A. We study the electronic structure of finite armchair graphene nanoribbons using density-functional theory and the Hubbard model, concentrating on the states localized at the zigzag termini. We show that the energy gaps between end-localized states are sensitive to doping, and that in doped systems, the gap between the end-localized states decreases exponentially as a function of the ribbon length. Doping also quenches the antiferromagnetic coupling between the end-localized states leading to a spin-split gap in neutral ribbons. By comparing dI/dV maps calculated using the many-body Hubbard model, its mean-field approximation and density-functional theory, we show that the use of a single-particle description is justified for graphene π states in case spin properties are not the main interest. Furthermore, we study the effect of structural defects in the ribbons on their electronic structure. Defects at one ribbon terminus do not significantly modify the electronic states localized at the intact end. This provides further evidence for the interpretation of a multipeak structure in a recent scanning tunneling spectroscopy (STS) experiment resulting from inelastic tunneling processes [van der Lit et al., Nat. Commun. 4, 2023]. Finally, we show that the hydrogen termination at the flake edges leaves identifiable fingerprints on the positive bias side of STS measurements, thus possibly aiding the experimental identification of graphene structures. Electronic states in finite graphene nanoribbons: Effect of charging and defects

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“…Band structures calculated by density functional theory with local spin-density approximation (DFT-LSDA) 7,27 show remarkable agreement with those obtained from a tight-binding model with a Hubbard term in the meanfield approximation 28 . Further studies treating the ee interaction beyond mean-field, such as Hartree-Fock with configuration interactions 29,30 and quantum Monte Carlo [31][32][33] , confirm that the mean-field approximation provides a good description of the magnetic ground-state properties of zigzag GNRs.…”

Section: B Model Hamiltonian: Electronic Structurementioning

confidence: 75%

Edge magnetization and local density of states in chiral graphene nanoribbons

2014

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We study the edge magnetization and the local density of states of chiral graphene nanoribbons using a π-orbital Hubbard model in the mean-field approximation. We show that the inclusion of a realistic next-nearest hopping term in the tight-binding Hamiltonian changes the graphene nanoribbons band structure significantly and affects its magnetic properties. We study the behavior of the edge magnetization upon departing from half filling as a function of the nanoribbon chirality and width. We find that the edge magnetization depends very weakly in the nanoribbon width, regardless of chirality as long as the ribbon is sufficiently wide. We compare our results to recent scanning tunneling microscopy experiments reporting signatures of magnetic ordering in chiral nanoribbons and provide an interpretation for the observed peaks in the local density of states, that does not depend on the antiferromagnetic interedge interaction.

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Magnetic Correlations in Short and Narrow Graphene Armchair Nanoribbons

Cited by 40 publications

References 32 publications

Competition of edge effects on the electronic properties and excitonic effects in short graphene nanoribbons

Competition of edge effects on the electronic properties and excitonic effects in short graphene nanoribbons

Electronic states in finite graphene nanoribbons: Effect of charging and defects

Edge magnetization and local density of states in chiral graphene nanoribbons

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