Comparison between experimental surface data and bulk structure models for quasicrystalline AlPdMn: Average atomic densities and chemical compositions

Ünal, Barış; Jenks, Cynthia J.; Thiel, Patricia A.

doi:10.1103/physrevb.77.195419

Cited by 40 publications

(30 citation statements)

References 57 publications

(95 reference statements)

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“…Previous studies have shown that although quasicrystal surfaces, like periodic crystalline surfaces, show atomic steps and thus expose different termination planes, these terminating planes have been found to be self-similar, and not random [29,30]. In the particular experiment described here, there is no uncertainty in the height of the adsorbate atoms above the surface because the structure of this quasicrystal is periodic perpendicular to the surface.…”

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confidence: 64%

Quantitative Adsorbate Structure Determination for Quasicrystals Using X-Ray Standing Waves

Diehl

et al. 2014

Phys. Rev. Lett.

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(2014) Quantitative adsorbate structure determination for quasicrystals using X-ray standing waves. Physical Review Letters, Volume 113 . Article number 106101. Permanent WRAP url: http://wrap.warwick.ac.uk/65512 Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work of researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.Copies of full items can be used for personal research or study, educational, or not-forprofit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. AbstractThe quantitative structure determination of adsorbed species on quasicrystal surfaces has so far appeared to present insurmountable problems. The normal incidence standing X-ray wavefield (NISXW) technique offers a simple solution, without extensive datasets or large computations. Its application to quasicrystals raises several conceptual difficulties that are related to the phase problem in X-ray diffraction. We demonstrate their solution for the case of Si atoms adsorbed on the decagonal Co-rich Al-Co-Ni quasicrystal to determine the local structure, comprising 6-atom clusters in particular hollow sites.

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confidence: 64%

Quantitative Adsorbate Structure Determination for Quasicrystals Using X-Ray Standing Waves

Diehl

et al. 2014

Phys. Rev. Lett.

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“…This surface [73][74][75] provides a quasiperiodic arrangement of local adsorption sites for Ag [68,69,71,73]. No two sites are exactly equivalent although similar motifs repeat quasiperiodically.…”

Section: Ag On 5-f I-al-pd-mn: Partial Propagation Of Quasicrystallinmentioning

confidence: 99%

“…This height selection is again attributed to QSE, as discussed further below. In the quasicrystalline substrate, different "layers" of atoms actually consist of a few vertically-closely-spaced planes of atoms, with the top layer being Alrich [73,74]. Likewise, the 3D Ag islands presumably consist of such "layers" with a selected height of 3 layers.…”

Section: Ag On 5-f I-al-pd-mn: Partial Propagation Of Quasicrystallinmentioning

confidence: 99%

From Initial to Late Stages of Epitaxial Thin Film Growth: STM Analysis and Atomistic or Coarse-Grained Modeling

Evans¹,

Han²,

Ünal³

et al. 2010

AIP Conference Proceedings

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Epitaxial thin film growth by vapor deposition or molecular beam epitaxy under ultra-high vacuum conditions generally occurs in two stages: (i) nucleation and growth of well-separated islands on the substrate; (ii) subsequent formation of a thicker continuous film with possible kinetic roughening. For homoepitaxial growth, two-dimensional (2D) monolayer islands are formed during submonolayer deposition. Typically, the presence of a step-edge barrier inhibits downward transport and leads to the formation of mounds (multilayer stacks of 2D islands) during multilayer growth. For heteroepitaxial growth, islands formed in the initial stages of deposition sometimes have a 2D monolayer structure. However, they may instead exhibit bilayer or 3D multilayer structure due to, e.g., a high film surface energy, strain, or quantum size effects. Various growth modes are possible for thicker films. Atomistic modeling provides the most detailed picture of film growth. For coherent (defect-free) epitaxial films, lattice-gas modeling analyzed by kinetic Monte Carlo simulation (KMC) is particularly successful in describing film growth on the appropriate time and length scales. For large islands or complex systems, another effective and instructive approach is laterally coarse-grained step-dynamics modelingwhich tracks only the evolution of step edges in each layer. However, fully coarse-grained 3D continuum modeling for the evolution of a film height function does not yet have predictive capability. Examples are provided for: Ag homoepitaxy on (100), (111) and (110) Abstract. Epitaxial thin film growth by vapor deposition or molecular beam epitaxy under ultra-high vacuum conditions generally occurs in two stages: (i) nucleation and growth of well-separated islands on the substrate; (ii) subsequent formation of a thicker continuous film with possible kinetic roughening. For homoepitaxial growth, two-dimensional (2D) monolayer islands are formed during submonolayer deposition. Typically, the presence of a step-edge barrier inhibits downward transport and leads to the formation of mounds (multilayer stacks of 2D islands) during multilayer growth. For heteroepitaxial growth, islands formed in the initial stages of deposition sometimes have a 2D monolayer structure. However, they may instead exhibit bilayer or 3D multilayer structure due to, e.g., a high film surface energy, strain, or quantum size effects. Various growth modes are possible for thicker films. Atomistic modeling provides the most detailed picture of film growth. For coherent (defect-free) epitaxial films, lattice-gas modeling analyzed by kinetic Monte Carlo simulation (KMC) is particularly successful in describing film growth on the appropriate time and length scales. For large islands or complex systems, another effective and instructive approach is laterally coarse-grained step-dynamics modeling which tracks only the evolution of step edges in each layer. However, fully coarse-grained 3D continuum modeling for the evolution of a film height function does not ...

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“…This chemical composition has also been confirmed experimentally. 31 The centers of the D tiles can be occupied Alternatively, the structure of the surface can be described by a -scaled P1 tiling Fig. 2͑a͒ shows the P1 and the P1 tiling and their relation to the DHBS.…”

Section: B Structure Of the Clean Fivefold Surface Of Al-pd-mnmentioning

confidence: 99%

Quasiperiodic Pb monolayer on the fivefoldi-Al-Pd-Mnsurface: Structure and electronic properties

et al. 2010

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Lead is one of few elements that adopts a pseudomorphic structure when deposited on quasicrystalline substrates. We present a structural model of quasiperiodic Pb overlayers formed on the fivefold surface of an icosahedral Al-Pd-Mn quasicrystal at two different coverages close to saturation. The skeleton of the Pb monolayer is formed by a network of "starfish" ͑SF͒ clusters formed at the initial stages of Pb deposition, as studied in detail in our previous work ͓Ledieu et al., Phys. Rev. B 79, 165430 ͑2009͔͒. The atomic structure of the Pb monolayers can be represented as a decorated pentagonal Penrose P1 tiling. The structural models reproduce also the quasiperiodic superstructure of the layers observed in experimental scanning tunneling microscopy ͑STM͒ images which is described by the -scaled P1 tiling ͑ is the golden mean͒. The atomic structure underlying the observed -scaled "white flower" motifs and the origin of irregular bright spots in STM images are discussed. The bright spots appear in the centers of the SF clusters centered at substrate sites occupied by Al atoms. The calculated electronic structure shows that the minimum in the density of states ͑pseudogap͒ at the Fermi level which is characteristic for the Al-Pd-Mn quasicrystals appears also in the local density of states of the adsorbed Pb monolayer. However, our analysis demonstrates that the formation of this pseudogap is not due to the quasiperiodic arrangement of the Pb atoms but to the strong hybridization of their orbitals with the substrate.

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Comparison between experimental surface data and bulk structure models for quasicrystalline AlPdMn: Average atomic densities and chemical compositions

Cited by 40 publications

References 57 publications

Quantitative Adsorbate Structure Determination for Quasicrystals Using X-Ray Standing Waves

Quantitative Adsorbate Structure Determination for Quasicrystals Using X-Ray Standing Waves

From Initial to Late Stages of Epitaxial Thin Film Growth: STM Analysis and Atomistic or Coarse-Grained Modeling

Quasiperiodic Pb monolayer on the fivefoldi-Al-Pd-Mnsurface: Structure and electronic properties

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