Electron localization in epitaxial graphene on Ru(0001) determined by moiré corrugation

Stradi, Daniele; Barja, Sara; Dı́az, Cristina; Garnica, Manuela; Borca, Bogdana; Hinarejos, J. J.; Sánchez‐Portal, Daniel; Alcamı́, Manuel; Arnau, A.; Parga, Amadeo L. Vázquez de; Miranda, Rodolfo; Martín, Fernando

doi:10.1103/physrevb.85.121404

Cited by 42 publications

(55 citation statements)

References 49 publications

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“…Regarding the basics of interlayer stacking, when two 2D lattices are overlaid, a lattice mismatch and/or an interlayer rotation leads to an additional periodic corrugation called a moiré pattern. 7 The moiré corrugation can behave like a periodic electron localization, 8,9 giving rise to minibands, quantum well confinement, [10][11][12][13] or other phenomena. For example, twisted bilayer graphene can exhibit an overlapping of Dirac cones, forming saddle points and resulting in a van Hove singularity that mediates enhancement of electronic phenomena such as the van der Waals interaction.…”

Section: Introductionmentioning

confidence: 99%

Moiré-related in-gap states in a twisted MoS2/graphite heterojunction

Butler

Huang

et al. 2017

npj 2D Mater Appl

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This report presents a series of low-temperature (4.5 K) scanning tunneling microscopy and spectroscopy experimental results on monolayer MoS 2 deposited on highly oriented pyrolytic graphite using chemical vapor deposition. To reveal the detailed connection between atomic morphology and conductivity in twisted MoS 2 /graphite heterojunctions, we employ high-sensitivity tunneling spectroscopy measurements by choosing a reduced tip-sample distance. We discern previously unobserved conductance peaks within the band gap range of MoS 2 , and by comparing the tunneling spectra from MoS 2 grains of varying rotation with respect to the substrate, show that these features have small but non-negligible dependence on the moiré superstructure. Furthermore, within a single moiré supercell, atomically resolved tunneling spectroscopy measurements show that the spectra between the moiré high and low areas are also distinct. These in-gap states are shown to have an energy shift attributed to their local lattice strain, matching corresponding behavior of the conduction band edge, and we therefore infer that these features are intrinsic to the density of states, rather than experimental artifacts, and attribute them to the twisted stacking and local strain energy of the MoS 2 /graphite heterointerface.

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Section: Introductionmentioning

confidence: 99%

Moiré-related in-gap states in a twisted MoS2/graphite heterojunction

Butler

Huang

et al. 2017

npj 2D Mater Appl

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“…14 Theoretical calculations, performed within the framework of density functional theory (DFT), 15 have played a major role supporting experiments, which have been performed aiming at shedding some light on both the electronic and geometric properties of these complex interfaces. [16][17][18][19][20][21] Two radically different approaches have been followed: on the one hand, very large models (formed by more than 500 atoms), have been employed. 16,[19][20][21][22][23] In such models, the in-plane lattice constant of graphene is maintained as much as possible to its equilibrium value (a = 2.46Å), so that, by considering large enough unit cells, the lattice mismatch between the graphene layer and the metal permits a realistic description of the consequently formed moiré pattern.…”

Section: Introductionmentioning

confidence: 99%

“…[16][17][18][19][20][21] Two radically different approaches have been followed: on the one hand, very large models (formed by more than 500 atoms), have been employed. 16,[19][20][21][22][23] In such models, the in-plane lattice constant of graphene is maintained as much as possible to its equilibrium value (a = 2.46Å), so that, by considering large enough unit cells, the lattice mismatch between the graphene layer and the metal permits a realistic description of the consequently formed moiré pattern. These models have been particularly helpful to elucidate the basic geometrical 16,19 and electronic 17,20 properties of these surfaces.…”

Section: Introductionmentioning

confidence: 99%

“…16,[19][20][21][22][23] In such models, the in-plane lattice constant of graphene is maintained as much as possible to its equilibrium value (a = 2.46Å), so that, by considering large enough unit cells, the lattice mismatch between the graphene layer and the metal permits a realistic description of the consequently formed moiré pattern. These models have been particularly helpful to elucidate the basic geometrical 16,19 and electronic 17,20 properties of these surfaces. Nevertheless, the computational cost associated with these realistic models is huge, 16 limiting somehow their applicability for more elaborate analysis.…”

Section: Introductionmentioning

confidence: 99%

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Lattice-matched versus lattice-mismatched models to describe epitaxial monolayer graphene on Ru(0001)

et al. 2013

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Monolayer graphene grown on Ru(0001) surfaces forms a superstructure with periodic modulations in its geometry and electronic structure. The large dimension and inhomogeneous features of this superstructure make its description and subsequent analysis a challenge for theoretical modeling based on density functional theory. In this work, we compare two different approaches to describe the same physical properties of this surface, focusing on the geometry and the electronic states confined at the surface. In the more complex approach, the actual moiré structure is taken into account by means of large unit cells, whereas in the simplest one, the graphene moiré is completely neglected by representing the system as a stretched graphene layer that adapts pseudomorphically to Ru(0001). As shown in previous work, the more complex model provides an accurate description of the existing experimental observations. More interestingly, we show that the simplified stretched models, which are computationally inexpensive, reproduce qualitatively the main features of the surface electronic structure. They also provide a simple and comprehensive picture of the observed electronic structure, thus making them particularly useful for the analysis of these and maybe other complex interfaces.

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“…Core-level photoemission has also shown nearly unaltered C1s spectra [11], suggesting that the graphene is indeed nearly freestanding on the Pt(111) substrate. In contrast, gr/Ru(0001) has a huge corrugation on the surface (a moiré corrugation), reflecting a lateral mismatch in the interlayer interaction [22][23][24][25][26][27][28][29][30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Probing interlayer interactions between graphene and metal substrates by supersonic rare-gas atom scattering

et al. 2015

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We demonstrate that highly surface-sensitive supersonic rare-gas (He, Ar, and Xe) atom scattering, in both the quantum and classical regimes, can probe and quantify the interlayer interactions between graphene monolayers and metal substrates in terms of the Debye temperature corresponding to the surface normal vibration, and the surface effective mass. As models of the strongly and weakly interacting graphene, we investigated two systems, graphene on Ru(0001) and Pt (111), respectively. The experimental data for Ar and Xe are compared with the results from theoretical simulations based on the classical smooth surface model. For gr/Pt(111) we find that the scattering pattern of the rare-gas beam, including the Debye-Waller attenuation of the He beam, are quite similar to that from highly oriented pyrolytic graphite (HOPG); this suggests that the graphene-Pt (111) interaction is much like a van der Waals interaction. On the contrary, for the gr/Ru(0001) system, we find a smaller Debye-Waller attenuation and a larger surface effective mass, indicating that graphene on Ru(0001) is tightly bonded to the substrate. Furthermore, asymmetrical spectral shapes in the Ar and Xe scattering spectra from gr/Ru(0001) are interpreted as a result of the lateral distribution of the interlayer interaction corresponding to the moiré pattern. It is found that the "valley" region of the moiré pattern has high effective mass reflecting stronger bonding to the substrate, contributing to the high reflectivity of the He beam reported for this system. On the other hand, the effective mass of the "hill" region is found to be similar to that of HOPG, indicating that this region is well decoupled from the substrate. These results demonstrate a unique capability of atom scattering to probe and evaluate the molecule-substrate interaction and its spatial distributions.

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Electron localization in epitaxial graphene on Ru(0001) determined by moiré corrugation

Cited by 42 publications

References 49 publications

Moiré-related in-gap states in a twisted MoS2/graphite heterojunction

Moiré-related in-gap states in a twisted MoS2/graphite heterojunction

Lattice-matched versus lattice-mismatched models to describe epitaxial monolayer graphene on Ru(0001)

Probing interlayer interactions between graphene and metal substrates by supersonic rare-gas atom scattering

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