Electronic transport in graphene nanoribbons with sublattice-asymmetric doping

Aktor, Thomas; Jauho, Antti–Pekka; Power, Stephen R.

doi:10.1103/physrevb.93.035446

Cited by 13 publications

(10 citation statements)

References 57 publications

(113 reference statements)

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“…More recent attempts have considered chemical modification through absorption, substitution, or sublattice symmetry breaking, for example, by doping. [13][14][15][16] Periodic patterning of graphene sheets, for example, periodic perforation to form so-called graphene antidot lattices (GAL) or nanomeshes, is of particular interest since theoretical predictions suggest the possibility of obtaining sizable band gaps. 17,18 Several groups have realized these structures in the lab .…”

Section: Introductionmentioning

confidence: 99%

Robust band gap and half-metallicity in graphene with triangular perforations

2016

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Ideal graphene antidot lattices are predicted to show promising band gap behavior (i.e., E G 500 meV) under carefully specified conditions. However, for the structures studied so far this behavior is critically dependent on superlattice geometry and is not robust against experimentally realistic disorders. Here we study a rectangular array of triangular antidots with zigzag edge geometries and show that their band gap behavior qualitatively differs from the standard behavior which is exhibited, e.g., by rectangular arrays of armchair-edged triangles. In the spin unpolarized case, zigzag-edged antidots give rise to large band gaps compared to armchair-edged antidots, irrespective of the rules which govern the existence of gaps in armchair-edged antidot lattices. In addition the zigzag-edged antidots appear more robust than armchair-edged antidots in the presence of geometrical disorder. The inclusion of spin polarization within a mean-field Hubbard approach gives rise to a large overall magnetic moment at each antidot due to the sublattice imbalance imposed by the triangular geometry. Half-metallic behavior arises from the formation of spin-split dispersive states near the Fermi energy, reducing the band gaps compared to the unpolarized case. This behavior is also found to be robust in the presence of disorder. Our results highlight the possibilities of using triangular perforations in graphene to open electronic band gaps in systems with experimentally realistic levels of disorder, and furthermore, of exploiting the strong spin dependence of the system for spintronic applications.

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Section: Introductionmentioning

confidence: 99%

Robust band gap and half-metallicity in graphene with triangular perforations

2016

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“…This is expected as defects located on a single sublattice break the sublattice symmetry, effectively turning the disordered system into gapped graphene 130 as also demonstrated in other theoretical works considering sublattice asymmetric disorder. 28,83,131 Band-gap openings have also been reported experimentally in ARPES on nitrogen-doped graphene 76 and graphene with hydrogen adatoms, 132 but the underlying mechanism is believed to be of a different nature; i.e., not associated with sublattice asymmetry.…”

Section: Sublattice Asymmetric Disordermentioning

confidence: 96%

Atomistic T -matrix theory of disordered two-dimensional materials: Bound states, spectral properties, quasiparticle scattering, and transport

Kaasbjerg

2020

Phys. Rev. B

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In this work, we present an atomistic first-principles framework for modeling the low-temperature electronic and transport properties of disordered two-dimensional (2D) materials with randomly distributed point defects (impurities). The method is based on the T -matrix formalism in combination with realistic density-functional theory (DFT) descriptions of the defects and their scattering matrix elements. From the T -matrix approximations to the disorder-averaged Green's function (GF) and the collision integral in the Boltzmann transport equation, the method allows calculations of, e.g., the density of states (DOS) including contributions from bound defect states, the quasiparticle spectrum and the spectral linewidth (scattering rate), and the conductivity/mobility of disordered 2D materials. We demonstrate the method by examining these quantities in monolayers of the archetypal 2D materials graphene and transition metal dichalcogenides (TMDs) contaminated with vacancy defects and substitutional impurity atoms. By comparing the Born and T -matrix approximations, we also demonstrate a strong breakdown of the Born approximation for defects in 2D materials manifested in a pronounced renormalization of, e.g., the scattering rate by the higherorder T -matrix method. As the T -matrix approximation is essentially exact for dilute disorder, i.e., low defect concentrations (c dis 1) or density (n dis A −1 cell where A cell is the unit cell area), our first-principles method provides an excellent framework for modeling the properties of disordered 2D materials with defect concentrations relevant for devices. arXiv:1911.00530v1 [cond-mat.mes-hall] 1 Nov 2019

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“…and the corresponding eigenfunctions ψ nkx = (2 n n! √ πℓ) −1/2 H n (y/ℓ) e −y 2 /2ℓ 2 e ikxx (9) with ℓ = (ℏ/m * ω 0 ) 1/2 and H n (y/ℓ) the Hermite polynomials.…”

Section: B Ordinary Waveguidesmentioning

confidence: 99%

Transport in armchair graphene nanoribbons and in ordinary waveguides

Zubair

Bahrami

Vasilopoulos

2019

Journal of Applied Physics

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We study dc and ac transport along armchair graphene nanoribbons using the k · p spectrum and eigenfunctions and general linear-response expressions for the conductivities. Then we contrast the results with those for transport along ordinary waveguides. In all cases we assess the influence of elastic scattering by impurities, describe it quantitatively with a Drude-type contribution to the current previously not reported, and evaluate the corresponding relaxation time for long-and short-range impurity potentials. We show that this contribution dominates the response at very low frequencies. In both cases the conductivities increase with the electron density and show cusps when new subbands start being occupied. As functions of the frequency the conductivities in armchair graphene nanoribbons exhibit a much richer peak structure than in ordinary waveguides: in the former intraband and interband transitions are allowed whereas in the latter only the intraband ones occur. This difference can be traced to that between the corresponding spectra and eigenfunctions.

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Electronic transport in graphene nanoribbons with sublattice-asymmetric doping

Cited by 13 publications

References 57 publications

Robust band gap and half-metallicity in graphene with triangular perforations

Robust band gap and half-metallicity in graphene with triangular perforations

Atomistic T -matrix theory of disordered two-dimensional materials: Bound states, spectral properties, quasiparticle scattering, and transport

Transport in armchair graphene nanoribbons and in ordinary waveguides

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