Surface Structural Transitions on the Icosahedral Quasicrystal<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Al</mml:mi></mml:mrow><mml:mrow><mml:mn>70</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Pd</mml:mi></mml:mrow><mml:mrow><mml:mn>20</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Mn</mml:mi></mml:mrow><mml:mro

Bolliger, B.; Erbudak, M.; Vvedensky, Dimitri D.; Zurkirch, M.; Kortan, A. R.

doi:10.1103/physrevlett.80.5369

Cited by 58 publications

(26 citation statements)

References 23 publications

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“…8,27 It also induces a phase transformation from a cubic overlayer to a quasicrystaline surface. 10,12,27 The evolution with temperature of the Mn concentration on the sputtered surface ͓see Fig. 2͑a͔͒ exhibits very similar changes as those observed on the cleaved surface.…”

Section: Discussionsupporting

confidence: 61%

“…First, the surface can be mechanically polished in air, cleaned by sputtering with noble gas atoms, and then annealed to remove the damage left by sputtering. [2][3][4][5][6][7][8][9][10][11][12] During this procedure significant changes in the chemical composition occur due to segregation, evaporation, and preferential sputtering. [6][7][8][9][10][11][12] In the second approach, the surfaces are cleaned by thermal evaporation of the oxide layer at very high temperatures.…”

Section: Introductionmentioning

confidence: 99%

“…[2][3][4][5][6][7][8][9][10][11][12]16,17 All these studies, with exception of Ref. 16, report the composition of sputterannealed surfaces measured by Auger electron spectroscopy ͑AES͒ and by ͑x-ray͒ photoelectron spectroscopy ͑XPS͒.…”

Section: Introductionmentioning

confidence: 99%

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Evolution of the composition and structure of cleaved and heat-treated icosahedral Al-Pd-Mn quasicrystal surfaces

Ebert¹,

Kluge²,

Grushko³

et al. 1999

Phys. Rev. B

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We investigated the changes in composition and structure induced by heat treatment of cleaved fivefold icosahedral Al-Pd-Mn quasicrystal surfaces by scanning electron microscopy and calibrated Auger electron spectroscopy. With increasing temperature we observed five different composition ranges of the surface coupled with distinct changes in the surface morphology. The changes in composition can be explained by successive evaporation and diffusion processes occurring with increasing temperatures. First, Mn evaporates from the uppermost surface layer, then Al evaporation starts and induces a further Mn evaporation leading to an enrichment in Pd. The enrichment is reduced by Mn diffusion from the bulk, Al diffusion from the bulk, and probably simultaneously occurring Pd desorption. Finally, a recrystallization of the surface is induced by the full diffusive mobility of all elements and preferential evaporation of Mn and to a lesser degree of Al. We also discuss the signature of the bonding configuration of Al in the Auger spectra of all investigated compositions.

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Section: Discussionsupporting

confidence: 61%

Section: Introductionmentioning

confidence: 99%

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Evolution of the composition and structure of cleaved and heat-treated icosahedral Al-Pd-Mn quasicrystal surfaces

Ebert¹,

Kluge²,

Grushko³

et al. 1999

Phys. Rev. B

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“…Other work by us 23,24 and from other groups [25][26][27] has shown that some or all of this rough structure is due to formation of a cubic overlayer with ͓110͔ orientation. Terraces start to appear at about 700 K, but clusters dot the terraces until 900 K, where finally only the large, smooth terraces remain.…”

Section: Resultsmentioning

confidence: 99%

Fine structure on flat surfaces of quasicrystalline Al-Pd-Mn

et al. 1999

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We have analyzed the fine structure revealed by scanning tunneling microscopy for a flat (within 0.8 Å) fivefold surface of i-Al-Pd-Mn. Even though features in the image appear to be arranged randomly, self-similar features are separated by distinct distances. The distribution of such distances is compatible with the separations between pseudo-Mackay icosahedra tangent to the topmost layer, and with separations between other cluster-based units. We propose that the fine structure is due to electronic structure imposed by the clusters. We have analyzed the fine structure revealed by scanning tunneling microscopy for a flat ͑within 0.8 Å͒ fivefold surface of i-Al-Pd-Mn. Even though features in the image appear to be arranged randomly, self-similar features are separated by distinct distances. The distribution of such distances is compatible with the separations between pseudo-Mackay icosahedra tangent to the topmost layer, and with separations between other cluster-based units. We propose that the fine structure is due to electronic structure imposed by the clusters. Keywords

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“…Sputtering changes the composition; annealing allows structural rearrangements. More specifically, sputtering followed by annealing to temperatures below about 700 K produces a crystalline phase, a B2 ͑CsCl-like͒ structure as revealed by several techniques, 14,[20][21][22] including LEED structural analysis. 23 Annealing to higher temperatures allows long-range bulk-surface equilibration, and a surface that displays characteristics consistent with a bulklike termination of the quasicrystalline structure.…”

Section: Introductionmentioning

confidence: 99%

Electronic structure of quasicrystalline surfaces: Effects of surface preparation and bulk structure

et al. 2000

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We elucidate the nature of the surface electronic properties of quasicrystalline Al-Pd-Mn. We do this by using photoelectron and Auger electron spectroscopies, and by making a variety of comparisons-across types of bulk samples, and across methods of surface preparation. The main conclusions are these: (i) The narrow Mn 2p 3/2 core-level line observed in the icosahedral phase is a fingerprint of a suppression in the density of states (a pseudogap) at the Fermi level and is not unique to the quasicrystalline phase. It is also independent of the symmetry of the quasicrystalline surface. The Auger line shape is also affected and may be used as a fingerprint of a pseudogap. (ii) A similarly narrow Fe 2p 3/2 core-level line characterizes the icosahedral Al-Cu-Fe quasicrystal, consistent with the expectation that the electronic structure is of general importance in the stabilization of icosahedral phases. (iii) In icosahedral Al-Pd-Mn, the pseudogap of the bulk is not retained up to the surface immediately after fracture, but can be restored by annealing, or by sputter annealing to sufficiently high temperatures. Assuming that the pseudogap reflects an electronic stabilization of the atomic structure, these results suggest that the heat-treated surfaces are more stable than the surface obtained by fracturing at room temperature. We elucidate the nature of the surface electronic properties of quasicrystalline Al-Pd-Mn. We do this by using photoelectron and Auger electron spectroscopies, and by making a variety of comparisons-across types of bulk samples, and across methods of surface preparation. The main conclusions are these: ͑i͒ The narrow Mn 2p 3/2 core-level line observed in the icosahedral phase is a fingerprint of a suppression in the density of states ͑a pseudogap͒ at the Fermi level and is not unique to the quasicrystalline phase. It is also independent of the symmetry of the quasicrystalline surface. The Auger line shape is also affected and may be used as a fingerprint of a pseudogap. ͑ii͒ A similarly narrow Fe 2p 3/2 core-level line characterizes the icosahedral Al-Cu-Fe quasicrystal, consistent with the expectation that the electronic structure is of general importance in the stabilization of icosahedral phases. ͑iii͒ In icosahedral Al-Pd-Mn, the pseudogap of the bulk is not retained up to the surface immediately after fracture, but can be restored by annealing, or by sputter annealing to sufficiently high temperatures. Assuming that the pseudogap reflects an electronic stabilization of the atomic structure, these results suggest that the heat-treated surfaces are more stable than the surface obtained by fracturing at room temperature.

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Surface Structural Transitions on the Icosahedral QuasicrystalAl70Pd20Mn

Cited by 58 publications

References 23 publications

Evolution of the composition and structure of cleaved and heat-treated icosahedral Al-Pd-Mn quasicrystal surfaces

Evolution of the composition and structure of cleaved and heat-treated icosahedral Al-Pd-Mn quasicrystal surfaces

Fine structure on flat surfaces of quasicrystalline Al-Pd-Mn

Electronic structure of quasicrystalline surfaces: Effects of surface preparation and bulk structure

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