Half-Metallic Zigzag Carbon Nanotube Dots

Hod, Oded; Scuseria, Gustavo E.

doi:10.1021/nn8004069

Cited by 70 publications

(80 citation statements)

References 95 publications

(332 reference statements)

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“…This state also has a frustrated AFM distribution of spins. Hod and Scuseria 14 have shown that δ(μ 0 T ) decreases sharply for long finite ZNTs, becoming lower than the thermal energy at room temperature (0.025 eV) in most cases. One of the aims of this work is to analyze the changes induced in the magnetic state of the nanotubes by the presence of an encapsulated iron cluster; we discuss this topic in the next section.…”

Section: B Finite Zigzag Carbon Nanotubesmentioning

confidence: 91%

“…The energy difference E(μ 0 T ) − E(AFM) between the lowest-lying magnetic state (with total magnetic moment μ 0 T ) and the ground state (AFM) decreases monotonically when the length of the nanotube increases, up to a point where the difference becomes lower than room temperature. 14 For the shortest zigzag carbon nanotubes, E(μ 0 T ) − E(AFM) increases when the diameter of the nanotube increases, showing an oscillating effect. 16 Our aim is to analyze the interplay between the singular magnetic properties of the finite ZNTs and the large magnetization of the encapsulated Fe clusters.…”

Section: Introductionmentioning

confidence: 93%

“…The two ends show opposite orientation of the atomic magnetic moments. [12][13][14][15] Other states are close in energy to the ground state: magnetic states (M) with net total magnetic moment μ T different from zero (in some of these, the magnetic moments at the two edges show the same orientation [13][14][15], and a nonmagnetic (NM) state showing local spin compensation along the nanotube. The energy difference E(μ 0 T ) − E(AFM) between the lowest-lying magnetic state (with total magnetic moment μ 0 T ) and the ground state (AFM) decreases monotonically when the length of the nanotube increases, up to a point where the difference becomes lower than room temperature.…”

Section: Introductionmentioning

confidence: 99%

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Electronic and magnetic properties of Fe clusters inside finite zigzag single-wall carbon nanotubes

et al. 2013

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Density functional calculations of the electronic structure of the Fe 12 cluster encapsulated inside finite singlewall zigzag carbon nanotubes of indices (11,0) and (10,0) have been performed. Several Fe 12 isomers have been considered, including elongated shape isomers aimed to fit well inside the nanotubes, and the icosahedral minimum energy structure. We analyze the structural and magnetic properties of the combined systems, and how those properties change compared to the isolated systems. A strong ferromagnetic coupling between the Fe atoms occurs both for the free and the encapsulated Fe 12 clusters, but there is a small reduction (3-7.4 μ B ) of the spin magnetic moment of the encapsulated clusters with respect to that of the free ones (μ = 38 μ B ). The reduction of the magnetic moment is mostly due to the internal redistribution of the spin charges in the iron cluster. In contrast, the spin magnetic moment of the carbon nanotubes, which is zero for the empty tubes, becomes nonzero (1-3 μ B ) because of the interaction with the encapsulated cluster. We have also studied the encapsulation of atomic Fe and the growth of small Fe n clusters (n = 2, 4, 8) encapsulated in a short (10,0) tube. The results suggest that the growth of nanowires formed by distorted tetrahedral Fe 4 units will be favorable in (10,0) nanotubes and nanotubes of similar diameter.

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Section: B Finite Zigzag Carbon Nanotubesmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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Electronic and magnetic properties of Fe clusters inside finite zigzag single-wall carbon nanotubes

et al. 2013

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“…49 (8, 16 )] to check the effect of the carbon circles on the electronic structure of the nanotube. The HOMO−LUMO energy gap of (8,0) BCNNT e is 1.00 eV, and the dipole moment is 20.2 D. The net charge on carbon atoms in BCNNTs is relatively small, and the carbon circles serve as a bridge for π conjugation, as revealed by the charge distribution of these nanotube clips ( Figure S1).…”

Section: ■ Models and Computational Detailsmentioning

confidence: 99%

Tuning the First Hyperpolarizabilities of Boron Nitride Nanotubes

et al. 2014

ACS Photonics

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Various carbon-substituted boron nitride (8,0) and (4,4) nanotubes are designed for application as nonlinear optical materials. The structure and first (static and frequencydependent) hyperpolarizabilities of these boron nitride nanotubes are predicted. The substitution of carbon in the boron nitride nanotube clip significantly enhances the first hyperpolarizabilities by up to several orders of magnitude. The doping pattern of the carbon circle and π electron conjugation are crucial in determining the large first hyperpolarizabilities of these nanotubes. KEYWORDS: carbon-substituted boron nitride nanotubes, first hyperpolarizability, frequency dispersion, charge transfer based electronic excitation N onlinear optical (NLO) materials have attracted increasing attention due to their potential important applications, e.g., laser tuning, frequency conversion, all-optical switches, signal processing, optical communication, information security, optical data storage processing, and biological imaging. 1,2 Minerals, 3 inorganic oxides, 4 semiconductors, 5 atomic clusters, 6 organometallic compounds, 7 and metal complexes 8−11 have been explored for these applications. Nanotubes could be potential NLO materials due to their unique structures and properties.Carbon nanotubes (CNTs) could be semiconducting or metallic depending on their chirality 12 with possible exceptions of CNTs (4,0) and (5,0). 13 On the other hand, boron nitride nanotubes (BNNTs) are electric insulators (or wide-gap semiconductors) with band gaps of about 5.5 eV 14 in spite of chirality and their tube diameter. 15 BNNT was predicted theoretically 16 before the experimental synthesis of single-and multiple-wall tubes. 17 The combination of BNNTs and CNTs (BCNNTs) could have some new properties due to the large property differences between BNNTs and CNTs, 18,19 and such combinations were the targets in the synthesis of nanotubes with desired properties. 20−25 The hybridized nanotubes with zigzag conformations may be semiconducting 23 with good thermal stability. The band gaps of hybridized armchair nanotubes [C 0.5 (BN) 0.5 ] do not change with the radius of the tubes. 24 The electronic structures of certain BCNNTs with proper hybridization, e.g., BC 2 N, depend on the radii or chiralities of the tubes, 25 providing new opportunities for the design of electronic devices.First-principles calculations predict large second-order nonlinear optical properties for BNNTs 26 and possible applications of BN-doped carbon nanotubes in NLO devices. 27 The NLO properties of zigzag BNNTs were predicted to converge to those of a hexagonal-BN sheet. 28 The bonding pattern of C with BN and the composition dictate the electronic structure of BCNNTs, 23−25 and the charge distributions have large effects on the NLO properties 29 of these tubes as well. The polarities, polarizabilities, and the second hyperpolarizabilities of armchair BCNNTs are significantly enhanced 30 with respect to those of BNNTs. However, hybridization of C with BN has little effect on the first hyper...

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“…The model consists of a zigzag, fixed-fixed, single-wall CNT. Zigzag refers to the chirality of the CNT, which is (n, m) ¼ (10, 0) [53]. The length L of the CNT is 52.62 Å and the CNT diameter D equals 7.83 Å.…”

Section: Defect Free Cnt Bucklingmentioning

confidence: 99%

Mechanics of Graphene and Carbon Nanotubes Under Uniaxial Compression and Tension

Poelma

Zhang

2014

Molecular Modeling and Multiscaling Issues for Electronic Material Applications

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In this chapter, we study the mechanics of nanostructures such as graphene sheets and carbon nanotubes under unidirectional compression and tension. The nanostructures are influenced by temperature effects and vacancy defects and their mechanical behavior is predicted using molecular dynamics (MD). The numerical MD models are validated by comparison with analytical models derived from continuum theory. A straight forward modeling approach is discussed to prescribe boundary conditions on the atoms and to extract reaction forces. This approach allows us to investigate various different loading cases as well as the effects of temperature and defects on the mechanical stability of nanostructures. Two case studies are presented in this chapter. Study (1) discusses the effects of vacancy defect position and temperature on the carbon nanotube (CNT) critical buckling load. The study considers (multiwall) CNTs of various diameters, lengths, and wall thicknesses. Study (2) focuses on the stability of uniaxial compressed graphene sheets with and without defects and hydrogen termination. In addition, the adhesive stability of graphene sheets on different substrates is investigated to study different graphene to substrate transfer routes.

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Half-Metallic Zigzag Carbon Nanotube Dots

Cited by 70 publications

References 95 publications

Electronic and magnetic properties of Fe clusters inside finite zigzag single-wall carbon nanotubes

Electronic and magnetic properties of Fe clusters inside finite zigzag single-wall carbon nanotubes

Tuning the First Hyperpolarizabilities of Boron Nitride Nanotubes

Mechanics of Graphene and Carbon Nanotubes Under Uniaxial Compression and Tension

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