Substrate-induced strain and orientational ordering in adsorbed monolayers

McTague, J. P.; Novaco, Anthony D.

doi:10.1103/physrevb.19.5299

Cited by 294 publications

(104 citation statements)

References 9 publications

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“…In general, Ψ6 > ψ , and when ψe6 is considerably lower than ψ6 it indicates that a preferred orientation of the adsorbate with respect to the substrate does not coincide with the substrate symmetry axes [18,19]. Finally, in the case of uniaxially ordered phase we expect that the bond-orientational order parameters will take some nontrivial values between 0 and 1.…”

Section: E P E N D S O N T H E O R I E N T a T I O N O F T H E S O mentioning

confidence: 99%

On Melting of Two-Dimensional Monolayer Films

1996

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The melting of two-dimensional films formed on the (100) fcc crystal is studied by Monte Carlo simulation. The results obtained suggest that in systems with only weakly corrugated surface potential, exhibiting the hexagonal close packed solid structure, the melting transition is followed by the lsing-like transition as predicted by the theory of Nelson and Halperin. In the case of highly corrugated surface potential, the film forms registered structure which disorders gradually as the temperature is raised.PACS numbers: 82.65.-i, 64.60.-i The mechanism of melting and disordering of twodimensional adsorbed solid phases is a subject of considerable current interest and hot controversy [1][2][3]. One of the questions is the adequacy of the picture provided by the theory developed by Kosterlitz, Thouless, Halperin, Nelson and Young (KTHNY) [4][5][6][7] to real experimental systems. The hitherto collected experimental data [1,[8][9][10] as well as the results of numerous computer simulations [1,[11][12][13][14] seldom lead to unambiguous conclusions. The KTHNY theory predicts that the melting of twodimensional solid phase on a "flat" (noncorugated) surface is a two-stage continuous process. In the first stage, due to dissociation of dislocation pairs, the system looses the quasi-long-range positional order, but retains the quasi-long-range orientational order. This corresponds to the transition from the solid to the hexatic phase. The second stage is connected with the disclination-unbinding transition, occurring at higher temperature ,and leading to the formation of isotropic liquid phase. This scenario is considerably altered by the presence of periodic substrate potential and the actual mechanism of melting depends on the symmetry and the size of the substrate surface lattice as well as on the amplitude of periodic variations of the gas-solid potential. In general, the presence of periodic potential is expected to wash out the disclination-unbinding transition, and hence the melting becomes (735)

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Section: E P E N D S O N T H E O R I E N T a T I O N O F T H E S O mentioning

confidence: 99%

On Melting of Two-Dimensional Monolayer Films

1996

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“…The Novaco-McTague model is the most well-known and accepted one. 7,8 It describes the monolayer in terms of the elastic constants and shows that the ground state of an adsorbed monolayer could be at a nonsymmetry angle respective to the substrate. The interaction of the adsorbate layer with the substrate is assumed to be very weak and the rotational epitaxy is mainly driven by the interactions between the adsorbate atoms.…”

Section: Introductionmentioning

confidence: 99%

Analytic theory of hexagonal monolayer interacting with hexagonal substrate

Tkatchenko

2006

Phys. Rev. B

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Analytic theory of the infinite rigid hexagonal monolayer interacting with hexagonal substrate is developed. The interaction potential is described by a Fourier series with up to six shells of the reciprocal cell vectors. It is rigorously shown that energy of minimum structures is directly related to their symmetry, assuming a decaying behavior of Fourier coefficients. Preliminary comparison with real systems of halogens and alkalis adsorbed on metal surfaces is encouraging and indicates that the adsorbate-substrate interaction is one of the main driving forces in the monolayer formation. The need of detailed ab initio calculations to obtain the Fourier coefficients for different complex adsorption systems is emphasized. Our results indicate the importance of accurate description of the adsorbate-substrate interactions for quantitative theory of monolayer epitaxy on well-ordered surfaces.

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“…That situation may lead to structural lubricity (sometimes called superlubricity), involving the possible vanishing of static friction and smooth sliding in the absence of defects. [1] On the other hand, the theory of incommensurate epitaxy, developed long ago in the context of adsorbed rare gas monolayers by Novaco & McTague [2,3] and others, [4,5] predicted a striking structural effect -immediately confirmed experimentally [6] -consisting of a small spontaneous misalignment angle θ = θ N M of the adsorbed monolayer as a whole relative to the substrate axes. Such misalignment influences the contact strength between lattices with several consequences including a change of friction, as recently found in a different context.…”

Section: Introductionmentioning

confidence: 99%

Graphene on h-BN: to align or not to align?

et al. 2017

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The contact strength, adhesion and friction, between graphene and an incommensurate crystalline substrate such as h-BN depends on their relative alignment angle θ. The well established Novaco-McTague (NM) theory predicts for a monolayer graphene on a hard bulk h-BN crystal face a small spontaneous misalignment, here θNM 0.45 degrees which if realized would be relevant to a host of electronic properties besides the mechanical ones. Because experimental equilibrium is hard to achieve, we inquire theoretically about alignment or misalignment by simulations based on dependable state-of-the-art interatomic force fields. Surprisingly at first, we find compelling evidence for θ = 0, i.e., full energy-driven alignment in the equilibrium state of graphene on h-BN. Two factors drive this deviation from NM theory. First, graphene is not flat, developing on h-BN a long-wavelength out-of-plane corrugation. Second, h-BN is not hard, releasing its contact stress by planar contractions/expansions that accompany the interface moiré structure. Repeated simulations by artificially forcing graphene to keep flat, and h-BN to keep rigid, indeed yield an equilibrium misalignment similar to θNM as expected. Subsequent sliding simulations show that friction of graphene on h-BN, small and essentially independent of misalignments in the artificial frozen state, strongly increases in the more realistic corrugated, strain-modulated, aligned state.

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Substrate-induced strain and orientational ordering in adsorbed monolayers

Cited by 294 publications

References 9 publications

On Melting of Two-Dimensional Monolayer Films

On Melting of Two-Dimensional Monolayer Films

Analytic theory of hexagonal monolayer interacting with hexagonal substrate

Graphene on h-BN: to align or not to align?

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