Magnetic ordering at the edges of graphitic fragments: Magnetic tail interactions between the edge-localized states

Lee, Hosik; Son, Young‐Woo; Park, Noejung; Han, Seungwu; Yu, Jaejun

doi:10.1103/physrevb.72.174431

Cited by 524 publications

(417 citation statements)

References 25 publications

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“…The localized edge states form a two-fold degenerate flat band at the Fermi energy (E F ), existing in about one third of the Brillouin zone away from the zone center 12,13,14,15 . By invoking band ferromagnetism, it has been suggested that an opposite spin orientation across the ribbon between ferromagnetically ordered localized edge states on each edge in ZGNRs is the ground-state spin configuration; that is, the total spin is zero 12,18,19 . Because the states around E F are the edge states and linear combinations of them, the effects of external transverse fields are expected to be significant on these states, in constrast with those on the extended states 20 .…”

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confidence: 99%

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Half-metallic graphene nanoribbons

Son

Cohen

Louie

2006

Nature

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146

3,556

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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 electrons with one spin orientation and insulating for electrons with the other. Such asymmetric electronic states for the different spins have been predicted for some ferromagnetic metals−for example, the Heusler compounds 1 −and were first observed in a manganese perovskite 2 . In view of the potential for use of this property in realizing spin-based electronics, substantial efforts have been made to search for half-metallic materials 3,4 . However, organic materials have hardly been investigated in this context even though carbonbased nanostructures hold significant promise for future electronic device 5 . Here we predict halfmetallicity in nanometre-scale graphene ribbons by using first-principles calculations. We show that this phenomenon is realizable if in-plane homogeneous electric fields are applied across the zigzag-shaped edges of the graphene nanoribbons, and that their magnetic property can be controlled by the external electric fields. The results are not only of scientific interests in the interplay between electric fields and electronic spin degree of freedom in solids 6,7 but may also open a new path to explore spintronics 3 at nanometre scale, based on graphene 8,9,10,11

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confidence: 99%

“…2b) is favored as the ground state over the configuration with same spin orientation between the two edges 12,18,19 . (The present result of antiferromagnetic spin configuration on the honeycomb lattice is consistent with a theorem for electrons on bipartite lattice 23 .)…”

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confidence: 99%

Half-metallic graphene nanoribbons

Son

Cohen

Louie

2006

Nature

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146

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“…This conclusion is in striking difference from the case of ZZ-GNRs, where the ground electronic state was found to have an AFM spin ordering regardless of the dimensions of the ribbon. [19][20][21][22][23][24][25][26]28,29,42,[45][46][47][48][49][50][51][52] Interestingly, contradicting results have been reported in the literature, 33 indicating that the ground state of unpassivated zigzag CNTs has a low-spin AFM ordering even for nanotubes that have earlier been considered to present a high-spin ferromagnetically ordered ground state. 32 In light of the considerable progress that has been made in the synthesis and fabrication of ultra-short [60][61][62][63][64] and open ended 65 CNTs and ultra-narrow GNRs, [66][67][68][69] it is desirable to obtain a full understanding of their electronic properties.…”

Section: Introductionmentioning

confidence: 93%

Half-Metallic Zigzag Carbon Nanotube Dots

Hod

Scuseria

2008

ACS Nano

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A comprehensive first-principles theoretical study of the electronic properties and half-metallic nature of finite zigzag carbon nanotubes is presented. Unlike previous reports, we find that all nanotubes studied present a spin-polarized ground state, where opposite spins are localized at the two zigzag edges in a long-range antifferomagnetic configuration. Relative stability analysis of the different spin states indicate that, for the shorter segments, spin-ordering should be present even at room temperature. The energy gap between the highest occupied and the lowest unoccupied molecular orbitals of the finite systems is found to be inversely proportional to the nanotubes segments length, suggesting a route to control their electronic properties. Similar to the case of zigzag graphene nanoribbons, half-metallic behavior is obtained under the influence of an external axial electric field.

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“…11 Magnetic effects are expected in the system due to the large state degeneracy at the Fermi level. 9,33,34 The DOS obtained when the electronic spin degree of freedom is included in the calculation is given in Fig. 6.…”

Section: B Characterization Of the Edge Statesmentioning

confidence: 99%

“…8 Calculations for zigzag-edged carbon strips without hydrogen termination indicate that the AFM state is also the lowest-energy state. 9 In contrast, the armchair-edged nanoribbons do not show such magnetic phases due to the delocalized nature of the frontier orbitals. 10 Similar magnetic effects related to the electronic states spatially localized at the zigzag edges have been also predicted for finite graphene nanoislands.…”

Section: Introductionmentioning

confidence: 99%

Half-metallic finite zigzag single-walled carbon nanotubes from first principles

et al. 2008

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Density-functional calculations predict half-metallicity in zigzag single-walled carbon nanotubes of finite length with the two ends saturated with hydrogen. We have analyzed the change of the ␣-and ␤-spin electronic gaps under the influence of an electric field applied along the nanotube axis. The half-metallic behavior, in which the electronic gap is zero for one spin flavor and nonzero for the other, is obtained for a critical electric field of 3.0/ w V / Å, where w is the length of the nanotube. This critical field is the same as that predicted for graphene nanoribbons. By a detailed analysis of the spin structure of the ground state, we show the relevance of the edge states, electronic states spatially localized at the carbon atoms of the nanotube boundaries, on the on-set of half-metallicity, and on the magnetic properties of the finite semiconducting zigzag nanotubes.

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Magnetic ordering at the edges of graphitic fragments: Magnetic tail interactions between the edge-localized states

Cited by 524 publications

References 25 publications

Half-metallic graphene nanoribbons

Half-metallic graphene nanoribbons

Half-Metallic Zigzag Carbon Nanotube Dots

Half-metallic finite zigzag single-walled carbon nanotubes from first principles

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