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

Ebert, Ph.; Kluge, F.; Grushko, B.; Urban, K.

doi:10.1103/physrevb.60.874

Cited by 36 publications

(17 citation statements)

References 20 publications

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“…We note that the decrease in Mn at the fracture surface of the icosahedral phase after annealing has been reported previously, based upon Auger electron spectroscopy. 54 The deficiency in Mn at the surface of i-Al-Pd-Mn prepared by sputter annealing has also been reported from earlier observations by low energy in scattering, 55 and surface x-ray diffraction. 56 Nothing is known about the structures of the topmost layers in Ј or Al 6 Mn, nor do we know whether an enhanced DOS will be observed for the fractured surfaces of these materials.…”

Section: Discussionsupporting

confidence: 64%

“…Published analysis of the fractured surface by STM revealed that over at least some of the surface, the cluster-subcluster structure evolves upon annealing toward a terrace-step topography. 10 In terms of electronic structure, the clusters are treated as spherical potential wells, each containing a magic number of electrons, corresponding to the exact filling of the electronic shells of the hierarchy of wells. The DOS is described as the superposition of the bonded states of the successive hierarchy of clusters.…”

Section: Discussionmentioning

confidence: 99%

“…Specifically, preparation of a clean surface by sputtering and annealing in ultrahigh vacuum can yield a surface with a terrace-step topography, [6][7][8] whereas preparation by fracture ͑also in ultrahigh vacuum͒ exposes a much rougher surface, dominated by a cluster structure. 9,10 As yet, it has not been determined whether these differences in topography are accompanied by differences in electronic structure. One of the goals of this paper is to explore this issue.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussionsupporting

confidence: 64%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2000

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“…29 The one-dimensional height modulation of the structure yielded quasiperiodically ordered rows as observed by STM. 29,30 There are similarities between the two systems in that Fibonacci sequences and the golden ratio are identified in both. 20,30 The difference between the two structures is that one is grown on a periodic substrate and one is grown on a quasicrystal substrate; thus the Ag film develops a quasicrystalline structure in response to the periodic potential of the GaAs, and while the Cu forms a structure in response to the aperiodic potential of the quasicrystal, and is therefore "pseudomorphic."…”

Section: B Comparison With Ag/ Gaas"110…mentioning

confidence: 96%

Copper adsorption on the fivefoldAl70Pd21Mn9quasicrystal surface

et al. 2005

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Recently we reported the formation of a quasiperiodic Cu thin film on the fivefold icosahedral Al-Pd-Mn quasicrystal using scanning tunneling microscopy, low energy electron diffraction, and Auger electron spectroscopy. Here we provide details pertaining to the growth, stability, and structure of this film. Structural information has been gained by LEED measurements carried out at 85 K. Cu atoms are organized periodically with a nearest-neighbor distance of 2.5±0.1 Å along the aperiodically spaced rows. Above 8 ML spontaneous mass transport resulting in island formation has been observed by STM. These observations point to ascending adatoms being responsible for the formation of 3D features. Finally, flashing the multilayer film to 570 K results in the desorption or diffusion of Cu into the bulk and the formation of five domains of a periodic structure. Disciplines Condensed Matter Physics | Metallurgy CommentsThis article is from Physical Review B 72 (2005) Recently we reported the formation of a quasiperiodic Cu thin film on the fivefold icosahedral Al-Pd-Mn quasicrystal using scanning tunneling microscopy, low energy electron diffraction, and Auger electron spectroscopy. Here we provide details pertaining to the growth, stability, and structure of this film. Structural information has been gained by LEED measurements carried out at 85 K. Cu atoms are organized periodically with a nearest-neighbor distance of 2.5± 0.1 Å along the aperiodically spaced rows. Above 8 ML spontaneous mass transport resulting in island formation has been observed by STM. These observations point to ascending adatoms being responsible for the formation of 3D features. Finally, flashing the multilayer film to 570 K results in the desorption or diffusion of Cu into the bulk and the formation of five domains of a periodic structure.

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“…[9][10][11][12][13][14][15][16][17] Annealing the sputtered surface at appropriate temperature routinely generates a stepterrace surface structure. In STM studies, an ultimate goal is to obtain high-resolution images displaying the fine structure ͑at the best, the direct images of the atomic arrangements͒ on these flat terraces, and to relate the surface structure to the atomic structure of a bulk model.…”

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confidence: 99%