Moiré beatings in graphene on Ru(0001)

Iannuzzi, Marcella; Kalichava, Irakli; Ma, Haifeng; Leake, Steven; Zhou, Haitao; Li, Geng; Zhang, Yi; Bunk, Oliver; Gao, Hongjun; Hutter, Jürg; Willmott, P. R.; Greber, Thomas

doi:10.1103/physrevb.88.125433

Cited by 38 publications

(66 citation statements)

References 29 publications

(42 reference statements)

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“…1,2 In particular, the unconventional magnetism in graphene based nanostructures is interesting, which may be utilized for spintronics applications. [3][4][5][6][7] Such graphene nanostructures have been fabricated experimentally, [8][9][10][11][12][13][14][15] and interestingly magnetism has been reported in nanographene, 16,17 disordered graphite, 18,19 and grain boundaries in highly oriented pyrolytic graphite. 20 The electronic structure of graphene nanostructure is different from the infinite graphene due to the edge effect.…”

Section: Introductionmentioning

confidence: 99%

Manipulation of edge magnetism in hexagonal graphene nanoflakes

Kabir

Saha‐Dasgupta

2014

Phys. Rev. B

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We explore possible ways to manipulate the intrinsic edge magnetism in hexagonal graphene nanoflake with zigzag edges, using density functional theory supplemented with on-site Coulomb interaction. The effect of carrier doping, chemical modification at the edge, and finite temperature on the edge magnetism has been studied. The magnetic phase diagram with varied carrier doping, and on-site Coulomb interaction is found to be complex. In addition to the intrinsic antiferromagnetic solution, as predicted for charge neutral hexagonal nanoflake, fully polarized ferromagnetic, and mixed phase solutions are obtained depending on the doped carrier concentration, and on-site Coulomb interaction. The complexity arises due to the competing nature of local Coulomb interaction and carrier doping, favoring antiferromagnetic and ferromagnetic coupling, respectively. Chemical modification of the edge atoms by hydrogen leads to partial quenching of local moments, giving rise to a richer phase diagram consisting of antiferromagnetic, ferromagnetic, mixed, and nonmagnetic phases. We further report the influence of temperature on the long-range magnetic ordering at the edge using ab initio molecular dynamics. In agreement with the recent experimental observations, we find that temperature can also alter the magnetic state of neutral nanoflake, which is otherwise antiferromagnetic at zero temperature. These findings will have important implications in controlling magnetism in graphene based low dimensional structures for technological purpose, and in understanding varied experimental reports.

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Section: Introductionmentioning

confidence: 99%

Manipulation of edge magnetism in hexagonal graphene nanoflakes

Kabir

Saha‐Dasgupta

2014

Phys. Rev. B

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“…Determination of the surface structure by standard tools such as dynamic low-energy electron diffraction [LEED I (V )], scanning tunneling microscopy (STM), and atomic force microscopy (AFM) is complicated due to the large size of the moiré unit cell and the resulting variations in the local density of states and chemical reactivity. [11][12][13][14][15][16] These difficulties have been illustrated by numerous examples on epitaxial graphene on metal single crystal substrates. 5,[17][18][19][20][21] The graphene-substrate interaction depends on the metal, leading to a variation in the electronic and topographic structure of the moiré, 5 and reactivity of the graphene layer.…”

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confidence: 99%

Structure and local variations of the graphene moiré on Ir(111)

et al. 2013

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We have studied the incommensurate moiré structure of epitaxial graphene grown on iridium(111) by dynamic low-energy electron diffraction [LEED I (V )] and noncontact atomic force microscopy (AFM) with a COterminated tip. Our LEED I (V ) results yield the average positions of all the atoms in the surface unit cell and are in qualitative agreement with the structure obtained from density functional theory. The AFM experiments reveal local variations of the moiré structure: The corrugation varies smoothly over several moiré unit cells between 42 and 56 pm. We attribute these variations to the varying registry between the moiré symmetry sites and the underlying substrate. We also observe isolated outliers, where the moiré top sites can be offset by an additional 10 pm. This study demonstrates that AFM imaging can be used to directly yield the local surface topography with pm accuracy even on incommensurate two-dimensional structures with varying chemical reactivity.

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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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Moiré beatings in graphene on Ru(0001)

Cited by 38 publications

References 29 publications

Manipulation of edge magnetism in hexagonal graphene nanoflakes

Manipulation of edge magnetism in hexagonal graphene nanoflakes

Structure and local variations of the graphene moiré on Ir(111)

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

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