Mechanism of magnetism in stacked nanographite with open shell electrons

Harigaya, Kikuo; Enoki, Toshiaki

doi:10.1016/s0009-2614(01)01338-0

Cited by 77 publications

(45 citation statements)

References 19 publications

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“…Even weak electron-electron interactions make the edge states magnetic, and the ferrimagnetic spin alignment along the zigzag edge is favored [15,18]. The existence of such magnetic states has been confirmed using mean-field theory [15,18,[26][27][28][29][30], the density matrix renormalization group for the Hubbard model [31] and density functional theory [21,[32][33][34]. Recent studies have shown the robustness of edge states to changes in their size and geometry [35][36][37][38][39][40].…”

Section: Introductionmentioning

confidence: 92%

Electronic states of graphene nanoribbons and analytical solutions

Wakabayashi

Sasaki

Nakanishi

et al. 2010

Science and Technology of Advanced Materials

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429

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Graphene is a one-atom-thick layer of graphite, where low-energy electronic states are described by the massless Dirac fermion. The orientation of the graphene edge determines the energy spectrum of π-electrons. For example, zigzag edges possess localized edge states with energies close to the Fermi level. In this review, we investigate nanoscale effects on the physical properties of graphene nanoribbons and clarify the role of edge boundaries. We also provide analytical solutions for electronic dispersion and the corresponding wavefunction in graphene nanoribbons with their detailed derivation using wave mechanics based on the tight-binding model. The energy band structures of armchair nanoribbons can be obtained by making the transverse wavenumber discrete, in accordance with the edge boundary condition, as in the case of carbon nanotubes. However, zigzag nanoribbons are not analogous to carbon nanotubes, because in zigzag nanoribbons the transverse wavenumber depends not only on the ribbon width but also on the longitudinal wavenumber. The quantization rule of electronic conductance as well as the magnetic instability of edge states due to the electron-electron interaction are briefly discussed.

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Section: Introductionmentioning

confidence: 92%

Electronic states of graphene nanoribbons and analytical solutions

Wakabayashi

Sasaki

Nakanishi

et al. 2010

Science and Technology of Advanced Materials

Self Cite

403

429

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“…When t is larger than U, the magnetic character is suppressed due to the strong itinerant property. We adopt the Hartree-Fock approximation to this model [5][6][7]:…”

Section: Model and Methodsmentioning

confidence: 99%

“…The Hubbard model [5][6][7] is applied to π-electrons on the curved molecules. We will discuss that the molecular structure determines the magnetism in the sumanene, while the edge state gives magnetism along the zigzag edge of a part of C 60 .…”

Section: Introductionmentioning

confidence: 99%

Possible Magnetic States in Buckybowl Molecules

Harigaya¹

2012

Jnl of Comp & Theo Nano

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Possible magnetic properties are studied in the buckybowl molecules: the sumanene and a part of C 60 . The Hubbard model is applied to the systems. We find that the molecular structure determines the magnetism in the sumanene. On the other hand, the edge state is found along the zigzag edge of a part of C 60 . Therefore, the novel property, transition from molecular magnetism to the magnetism like in nanographene, is found.

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“…The mechanism of the magnetic switching phenomenon can be explained theoretically on the basis of the Hubbard model for a loose stack of nanographene sheets. 39 The magnetic switching phenomenon is universal, and can be observed for other guest molecules though the behavior is modified depending on their chemical features. 40 Here, the key point is the presence of hydroxy group as we can know by comparing various guest molecules with and without hydroxy group, as summarized in Figure 10 with H 2 O, CH 3 OH, C 2 H 5 OH, (CH 3 ) 2 CO, C 6 H 6 , CHCl 3 , CCl 4 , C 6 H 12 , C 6 H 14 , as physisorbed guests.…”

Section: Magnetic Switching Phenomenonmentioning

confidence: 99%

Magnetic Edge State of Nanographene and Unconventional Nanographene-Based Host–Guest Systems

Enoki¹,

Takai²,

Kiguchi³

2012

Bulletin of the Chemical Society of Japan

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Nanographene, nanosized fragments of graphene, has edge-shape-dependent electronic structures different from those of infinite size graphene. Around the zigzag-shaped edges of a nanographene sheet, a nonbonding edge state of ³-electron origin is created, which is the origin of electronic and chemical activities of nanographene. In addition, the strongly spin-polarized edge state has localized spin, giving magnetic activity. We investigate the magnetic properties of nanoporous activated carbon fibers consisting of a three-dimensional disordered network of nanographite domains, each of which is a stack of 34 nanographene sheets, in relation to hostguest interaction. Chemically inert guest species such as water, organic solvent, or argon, physisorptively condensed into the nanopores mechanically compress the nanographite domains, resulting in high spin/low spin magnetic switching of the edge-state spins. The presence of an energy gap and the nanographene edges decorated by oxygen-containing functional groups make nanographene less amphoteric, modifying charge-transfer mechanisms in the hostguest interaction. HNO 3 shows a two-step charge-transfer process. In Br adsorption, physisorbed Br species cooperate with charge-transfer Br species, giving an interesting interplay of charge transfer and magnetic switching phenomena. In the K adsorption, physisorbed K atoms form antiferromagnetic K clusters in the nanopores, while a portion of K species are responsible for charge transfer. The reaction with fluorine creates magnetic ·-dangling bond states, at the expense of the ³-conjugated electron system. The interplay between the edge-state spins and the ·-dangling bond spins gives a variety of magnetism depending on the fluorine concentration.

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Mechanism of magnetism in stacked nanographite with open shell electrons

Cited by 77 publications

References 19 publications

Electronic states of graphene nanoribbons and analytical solutions

Electronic states of graphene nanoribbons and analytical solutions

Possible Magnetic States in Buckybowl Molecules

Magnetic Edge State of Nanographene and Unconventional Nanographene-Based Host–Guest Systems

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