Impurity invisibility in graphene: Symmetry guidelines for the design of efficient sensors

Duffy, J. M.; Lawlor, James A.; Lewenkopf, Caio; Ferreira, M. S.

doi:10.1103/physrevb.94.045417

Cited by 26 publications

(30 citation statements)

References 38 publications

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“…We note in passing that we observe, similar to Ref. [45], that the top-bonded impurities are strong scatterers compared to other impurity configurations, and the local bond-current profiles significantly rearrange and focus due to the impurities [30,77].…”

Section: Resultssupporting

confidence: 81%

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Time-resolved impurity-invisibility in graphene nanoribbons

et al. 2019

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We investigate time-resolved charge transport through graphene nanoribbons supplemented with adsorbed impurity atoms. Depending on the location of the impurities with respect to the hexagonal carbon lattice, the transport properties of the system may become invisible to the impurity due to the symmetry properties of the binding mechanism. This motivates a chemical sensing device since dopants affecting the underlying sublattice symmetry of the pristine graphene nanoribbon introduce scattering. Using the time-dependent Landauer-Büttiker formalism, we extend the stationary current-voltage picture to the transient regime, where we observe how the impurity invisibility takes place at sub-picosecond time scales further motivating ultrafast sensor technology. We further characterize time-dependent local charge and current profiles within the nanoribbons, and we identify rearrangements of the current pathways through the nanoribbons due to the impurities. We finally study the behavior of the transients with ac driving which provides another way of identifying the lattice-symmetry breaking caused by the impurities. arXiv:1903.12538v1 [cond-mat.mes-hall]

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Section: Resultssupporting

confidence: 81%

“…2. The impurities can connect to the pristine GNR in four different configurations: 'Center' (C), 'Bridge' (B), 'Top' (T), and 'Substitutional' (S) [45]. For the impurities we set imp = 0.66γ and γ imp = −2.2γ in Eq.…”

Section: Resultsmentioning

confidence: 99%

Time-resolved impurity-invisibility in graphene nanoribbons

et al. 2019

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“…27,30,32,78 The energy of such quasibound states depends on the interaction between the defect and the graphene lattice which is highly sensitive to the position of the defect. 33,79,80 For vacancies and substitutional atoms, quasibound states with energies in direct vicinity of the Dirac point arise in a robust manner. In transport, such defects act as resonant scatterers exhibiting a strong peak in the scattering cross section at the resonance energy which suppresses the conductivity 124,125 and affects electron cooling.…”

Section: Disordered Graphenementioning

confidence: 99%

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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“…3(a). E 2s of the Li 2s state as well as the invisibility of shortrange impurity potentials due to adatoms in the hollow site [35,55,56]. At higher energies, both the intra and intervalley rates increase dramatically and peak at the energy ε ≈ 1.75 eV of the van Hove singularity (vHS) in the DOS in Fig.…”

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confidence: 94%

Signatures of adatom effects in the quasiparticle spectrum of Li-doped graphene

Kaasbjerg

Jauho

2019

Phys. Rev. B

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We study the spectral function and quasiparticle scattering in Li-decorated graphene (Li@graphene) with an atomistic T -matrix formalism and uncover adatom-induced spectral effects which shed light on experimentally observed angle-resolved photoemission spectroscopy (ARPES) features. From transport studies, alkali adatoms are known to introduce charged-impurity scattering limiting the carrier mobility. Here, we demonstrate that Li adatoms furthermore give rise to a low-energy impurity band centered at the Γ point which originates from the hybridization between the atomic 2s state of the Li adatoms and graphene "surface" states. We show that the impurity band is strongly dependent on the concentration cLi of Li adatoms, and aligns with the Li-induced Fermi level on the Dirac cone at cLi ∼ 8 % (EF ≈ 1.1 eV). Finally, we show that adatom-induced quasiparticle scattering increases dramatically at energies above ∼ 1 eV close to the van Hove singularity in the graphene density of states (DOS), giving rise to a large linewidth broadening on the Dirac cone with a concomitant downshift and a characteristic kink in the conduction band. Our findings are highly relevant for future studies of ARPES, transport, and superconductivity in adatom-doped graphene.

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Impurity invisibility in graphene: Symmetry guidelines for the design of efficient sensors

Cited by 26 publications

References 38 publications

Time-resolved impurity-invisibility in graphene nanoribbons

Time-resolved impurity-invisibility in graphene nanoribbons

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

Signatures of adatom effects in the quasiparticle spectrum of Li-doped graphene

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