Spin and band-gap engineering in doped graphene nanoribbons

Gorjizadeh, Narjes; Farajian, Amir A.; Esfarjani, Keivan

doi:10.1103/physrevb.78.155427

Cited by 137 publications

(94 citation statements)

References 24 publications

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“…29 This leads to impurity distributions heavily weighted towards the edge sites -an observation confirmed elsewhere in the literature. [30][31][32][33][34][35][36] In addition to the binding energy, the magnitude of the magnetic moment on an impurity atom should also depend on impurity position. We shall demonstrate here that the principal features of this dependence derive from the underlying electronic structure of the GNR host.…”

Section: -27mentioning

confidence: 99%

Magnetization profile for impurities in graphene nanoribbons

et al. 2011

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The magnetic properties of graphene-related materials and in particular the spin-polarised edge states predicted for pristine graphene nanoribbons (GNRs) with certain edge geometries have received much attention recently due to a range of possible technological applications. However, the magnetic properties of pristine GNRs are not predicted to be particularly robust in the presence of edge disorder. In this work, we examine the magnetic properties of GNRs doped with transitionmetal atoms using a combination of mean-field Hubbard and Density Functional Theory techniques. The effect of impurity location on the magnetic moment of such dopants in GNRs is investigated for the two principal GNR edge geometries -armchair and zigzag. Moment profiles are calculated across the width of the ribbon for both substitutional and adsorbed impurities and regular features are observed for zigzag-edged GNRs in particular. Unlike the case of edge-state induced magnetisation, the moments of magnetic impurities embedded in GNRs are found to be particularly stable in the presence of edge disorder. Our results suggest that the magnetic properties of transitionmetal doped GNRs are far more robust than those with moments arising intrinsically due to edge geometry.

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Section: -27mentioning

confidence: 99%

Magnetization profile for impurities in graphene nanoribbons

et al. 2011

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“…[13][14][15] As quasi 1D materials, GNRs are extremely sensitive to their surrounding conditions, which provides a route for manipulating their electronic properties. Additionally, other factors such as finite size effect, 16,17 edge effect, [18][19][20][21][22][23] and the presence of strain [24][25][26][27] could be used to effectively tune the electronic properties GNRs.…”

Section: Introductionmentioning

confidence: 99%

Band gap engineering in finite elongated graphene nanoribbon heterojunctions: Tight-binding model

Tayo

2015

AIP Advances

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A simple model based on the divide and conquer rule and tight-binding (TB) approximation is employed for studying the role of finite size effect on the electronic properties of elongated graphene nanoribbon (GNR) heterojunctions. In our model, the GNR heterojunction is divided into three parts: a left (L) part, middle (M) part, and right (R) part. The left part is a GNR of width WL, the middle part is a GNR of width WM , and the right part is a GNR of width WR. We assume that the left and right parts of the GNR heterojunction interact with the middle part only. Under this approximation, the Hamiltonian of the system can be expressed as a block tridiagonal matrix. The matrix elements of the tridiagonal matrix are computed using real space nearest neighbor orthogonal TB approximation. The electronic structure of the GNR heterojunction is analyzed by computing the density of states. We demonstrate that for heterojunctions for which WL = WR, the band gap of the system can be tuned continuously by varying the length of the middle part, thus providing a new approach to band gap engineering in GNRs. Our TB results were compared with calculations employing divide and conquer rule in combination with density functional theory (DFT) and were found to agree nicely. I. INTRODUCTIONGraphene is a two-dimensional (2D) allotrope of carbon with excellent electronic and mechanical properties, making it suitable for multiple applications in nanoscale electronics and nanophotonics. 1,2 A major deficiency in graphene's properties is the absence of a band gap rendering it impossible for use in switching circuits. 3 Several approaches have been used to induce a band gap in graphene such as electrically gated bilayer graphene, 4-6 substrate induced band gap, 7,8 or isoelectronic codoping with boron and nitrogen. 9 Recently, it has become possible to engineer the band gap of graphene by etching or patterning along a given direction to produce ultra narrow quasi one-dimensional (1D) nano sheets referred to as graphene nanoribbons (GNRs) [10][11][12] with remarkable properties such as width-dependent tunable band gaps, exciton-dominated optical spectra, and room temperature ballistic transport. [13][14][15] As quasi 1D materials, GNRs are extremely sensitive to their surrounding conditions, which provides a route for manipulating their electronic properties. Additionally, other factors such as finite size effect, 16,17 edge effect, 18-23 and the presence of strain 24-27 could be used to effectively tune the electronic properties GNRs.

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“…Gorjizadeh et al 7 have reported the spin and band-gap controlling by ab initio calculation in doped GNRs. Park et al 14 In this paper, we present a spin dependent study on the electronic and transport properties of perfect and Be edge-doped ZGNRs.…”

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confidence: 99%

“…As we know, the substitutional doping of the alkaline earth metal Be atoms in Silicon is feasible. 15 The band structure of armchair GNRs doped with the alkaline earth metal Mg atoms has been calculated by N. Gorjizadeh et al 16 and our first principle calculation suggests that the substitutional doping of Be atoms in ZGNRs is stable. In the following, we use the 3-, ZGNRs so the interfaces between them have less effect on the transport than those in conventional metal -conductor -metal systems.…”

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confidence: 99%

“…This suggests that ZGNRs may play an important role in quantum electronic devices in the future and have ample potential in spintronic applications. 7,8 In general, we can manipulate the electronic properties of GNRs by defect, [9][10][11] impurity doping, [12][13][14] GNRs using a no-spin model. 24 Furthermore, it has been realized recently that the spin can play an important role in GNR properties like opening energy gap near the Fermi energy and making ZGNRs semiconductors.…”

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confidence: 99%

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Negative differential spin conductance in doped zigzag graphene nanoribbons

Wang

Zhai

et al. 2012

Applied Physics Letters

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The spin dependent charge transport in zigzag graphene nanoribbons (ZGNRs) has been investigated by the nonequilibrium Green's function method combined with the density functional theory at the local spin density approximation. The current versus voltage curve shows distinguished behaviors for symmetric and asymmetric ZGNRs and the doping on the ZGNR edges can manipulate the spin transport. In special cases that a Be atom is substitutionally doped on one edge of the symmetric ZGNRs, one spin current shows negative differential resistance while the other increases monotonically with the bias. This property might be used to design spin oscillators or other devices for spintronics.

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Spin and band-gap engineering in doped graphene nanoribbons

Cited by 137 publications

References 24 publications

Magnetization profile for impurities in graphene nanoribbons

Magnetization profile for impurities in graphene nanoribbons

Band gap engineering in finite elongated graphene nanoribbon heterojunctions: Tight-binding model

Negative differential spin conductance in doped zigzag graphene nanoribbons

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