Semiconducting Al–transition-metal quasicrystals

Krajčı́, M.; Häfner, J.

doi:10.1103/physrevb.68.165202

Cited by 35 publications

(39 citation statements)

References 48 publications

(59 reference statements)

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“…In any case, the existence of a deep pseudogap is an indication of a considerable degree of covalency in the interaction between the Al and the transition-metal atoms. 33 Previous investigations ͑both theoretical 30 and experimental 34 ͒ of the surface electronic structure of i-Al-Pd-Mn have demonstrated that the metallic character of the bonding is enhanced at the surface and that the pseudogap is partially leveled out as a consequence of a strong relaxation of the near-surface Al atoms. The present work extends these studies to the electronic structure of a well-ordered quasiperiodic adlayer and we find that the pseudogap has disappeared.…”

Section: Resultsmentioning

confidence: 99%

Quasiperiodic layers of free-electron metals studied using electron diffraction

et al. 2009

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Using electron diffraction, we show that free-electron metals, such as sodium and potassium, form a highly regular quasiperiodic monolayer on the fivefold surface of icosahedral Al-Pd-Mn and that the quasiperiodicity propagates up to the second layer in sodium. Our photoelectron spectroscopy results show that the quasicrystalline alkali-metal adlayer does not exhibit a pseudogap near the Fermi level thought to be characteristic for the electronic structure of quasicrystalline materials. Calculations based on density functional theory provide a model structure for the quasicrystalline alkali-metal monolayer and confirm the absence of a pseudogap. Disciplines Metallurgy CommentsThis article is from Physical Review B 79 (2009) Using electron diffraction, we show that free-electron metals, such as sodium and potassium, form a highly regular quasiperiodic monolayer on the fivefold surface of icosahedral Al-Pd-Mn and that the quasiperiodicity propagates up to the second layer in sodium. Our photoelectron spectroscopy results show that the quasicrystalline alkali-metal adlayer does not exhibit a pseudogap near the Fermi level thought to be characteristic for the electronic structure of quasicrystalline materials. Calculations based on density functional theory provide a model structure for the quasicrystalline alkali-metal monolayer and confirm the absence of a pseudogap.

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Section: Resultsmentioning

confidence: 99%

Quasiperiodic layers of free-electron metals studied using electron diffraction

et al. 2009

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“…DFT calculations have been used previously 2,7,8,[17][18][19] to calculate the geometric and electronic structures of the surfaces of quasicrystalline approximants and of pseudomorphic adlayers formed on these surfaces. Using the results for the surface electronic structure, simulated STM images 13 were generated and the good agreement with experimental images confirmed the validity of the theoretical structure models.…”

Section: Introductionmentioning

confidence: 99%

“…7,8,19 The calculations have demonstrated that unsupported quasiperiodic monolayers are not stable and that quasiperiodic ordering in an adsorbed monolayer results from the strong binding of adatoms to quasiperiodically distributed adsorption sites. 7 A Penrose P1 tiling consisting of pentagons, pentagonal stars, boats, and thin golden rhombi can be superimposed on the atomic structure of the five-fold surface.…”

Section: Introductionmentioning

confidence: 99%

“…7 For adatoms from groups I to III of the Periodic Table, it has been shown that they occupy surface vacancies, vertices of the P1 tiling, and quasiperiodically distributed chargedensity minima. 18,19 Surface vacancies bind adatoms most strongly, but atoms trapped in these sites are incorporated in the surface layer and do not form part of the quasiperiodic adlayers. It is found that in addition to strong binding at quasiperiodically distributed sites, the atomic radius of adatoms and the overlayer density play a crucial role in determining the stability of the quasiperiodic ordering of the absorbed monolayer.…”

Section: Introductionmentioning

confidence: 99%

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Nucleation of Pb starfish clusters on the five-fold Al-Pd-Mn quasicrystal surface

et al. 2009

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The nucleation of Pb clusters on the five-fold Al-Pd-Mn quasicrystal surface has been investigated using scanning tunneling microscopy (STM) and ab initio calculations based on density-functional theory (DFT). In the submonolayer regime, Pb atoms are highly mobile and adsorb preferentially within equatorially truncated pseudo-Mackay clusters present at the surface. The decoration of these unique adsorption sites leads to the formation of five-fold islands dubbed "starfish" and eventually to a quasiperiodic Pb monolayer. From a comparison of measured and calculated STM images it is concluded that most starfish clusters on all terraces are composed of ten Pb adatoms. A model of the structure of the starfish cluster has been proposed. Our total-energy calculations confirm its stability. The experimentally measured height profile of the starfish cluster is also reproduced by the DFT calculations. Disciplines Condensed Matter Physics | Metallurgy CommentsThis article is from Physical Review B 79 (2009) The nucleation of Pb clusters on the five-fold Al-Pd-Mn quasicrystal surface has been investigated using scanning tunneling microscopy ͑STM͒ and ab initio calculations based on density-functional theory ͑DFT͒. In the submonolayer regime, Pb atoms are highly mobile and adsorb preferentially within equatorially truncated pseudo-Mackay clusters present at the surface. The decoration of these unique adsorption sites leads to the formation of five-fold islands dubbed "starfish" and eventually to a quasiperiodic Pb monolayer. From a comparison of measured and calculated STM images it is concluded that most starfish clusters on all terraces are composed of ten Pb adatoms. A model of the structure of the starfish cluster has been proposed. Our total-energy calculations confirm its stability. The experimentally measured height profile of the starfish cluster is also reproduced by the DFT calculations.

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“…26,27 Several studies have identified these cut clusters as strong adsorption sites. 7,[28][29][30][31][32] Therefore the 8.0 Å Pb pentagons might result from the preferential adsorption of adatoms at these specific sites. The motif shown in Fig flowerlike motif of the clean surface but 2 scaled.…”

Section: A Pb Adsorption On the Fivefold Surface Of The I-al-cu-fe Qmentioning

confidence: 99%

Aperiodic and modulated Pb thin films on fivefold icosahedral Al-Cu-Fe and Al(111): Tailoring the structure of Pb

et al. 2009

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We report on the growth of Pb thin films deposited either on the Al-rich fivefold surface of the icosahedral AlCu-Fe quasicrystal or on the (111) surface of fcc Al. On the quasicrystalline substrate, the diffusion length of Pb adatoms is short due to heterogeneous nucleation that enforces a quasiperiodic structure in the monolayer. On the Al(111) substrate, the mobility of Pb adatoms is high and the interaction with the substrate is flatter, leading to the formation of a (√31×√31)R8.95° higher-order commensurate structure. This moiré structure propagates up to the highest coverages investigated. Disciplines Condensed Matter Physics | Metallurgy CommentsThis article is from Physical Review B 79 (2009) We report on the growth of Pb thin films deposited either on the Al-rich fivefold surface of the icosahedral Al-Cu-Fe quasicrystal or on the ͑111͒ surface of fcc Al. On the quasicrystalline substrate, the diffusion length of Pb adatoms is short due to heterogeneous nucleation that enforces a quasiperiodic structure in the monolayer. On the Al͑111͒ substrate, the mobility of Pb adatoms is high and the interaction with the substrate is flatter, leading to the formation of a ͑ͱ31ϫ ͱ 31͒R8.95°higher-order commensurate structure. This moiré structure propagates up to the highest coverages investigated.

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Semiconducting Al–transition-metal quasicrystals

Cited by 35 publications

References 48 publications

Quasiperiodic layers of free-electron metals studied using electron diffraction

Quasiperiodic layers of free-electron metals studied using electron diffraction

Nucleation of Pb starfish clusters on the five-fold Al-Pd-Mn quasicrystal surface

Aperiodic and modulated Pb thin films on fivefold icosahedral Al-Cu-Fe and Al(111): Tailoring the structure of Pb

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