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Umezawa, Koji; Nakanishi, Shigemitsu; Yumura, Takahiro; Gibson, W. M.; Watanabe, Masatoshi; Kido, Yoshiaki; Yamamoto, S.; Aoki, Yasushi; Naramoto, H.

doi:10.1103/physrevb.56.10585

Cited by 34 publications

(16 citation statements)

References 17 publications

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“…• surface alloy was also found in the literature, where annealing to T > 850 K followed deposition at RT before alloy formation occurred [16][17][18][19]. A further increase in coverage results in dealloying and the formation of a Pb wetting layer that covers the entire surface above θ Pb/Ni ≈ 0.40 ML.…”

Section: Wetting Layer Propertiessupporting

confidence: 67%

Quantum size effects on surfaces without a projected bandgap: Pb/Ni(111)

et al. 2011

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Abstract. We have studied the initial growth of Pb on Ni(111) using lowenergy electron microscopy (LEEM) and selective area low-energy electron diffraction (µLEED). First, a one-layer-high wetting layer develops that consists of small (7 × 7) and (4 × 4) domains. For larger coverages, Pb mesas are formed that are embedded in the wetting layer. In spite of the absence of a projected bandgap on clean Ni(111), we observe distinct quantum size effect (QSE)-driven preferred heights. These are apparent from a variety of frequently occurring island height transitions during growth, both on wide terraces and across substrate steps. Also, the average island heights that evolve during deposition at 422 and 474 K show a clear signature of QSE-driven preferred heights. These distinctly include five, seven and nine layers and thus correspond nicely to the values obtained in the key examples of QSE: Pb films on Si(111) and Ge(111). We suggest that the Pb-induced surface modification of Ni(111) shifts the Fermi level into the gap of the interface projected Ni bulk bands, thereby effectively causing decoupling of the Pb states with the bulk Ni states.

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Section: Wetting Layer Propertiessupporting

confidence: 67%

Quantum size effects on surfaces without a projected bandgap: Pb/Ni(111)

et al. 2011

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“…3 (a), (b) and (c) respectively. The I(T) data for the p( 3 3) R30 ¥ ∞ structure of lead on Ni(111) surface have not been recorded because of Ni-Pb alloy formation in the first atomic layer [8,9] and connected with this fact difficulties to calculate surface Debye temperature of an alloy. The slope is inversely proportional to the square of the surface Debye temperature Θ D .…”

Section: Resultsmentioning

confidence: 97%

Debye temperature of the Pb layers on Ni(111)

Krupski

2006

Physica Status Solidi (b)

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Low-energy electron diffraction (LEED) was used to investigate the surface Debye temperature (Θ D ) for p(1 × 1)-Ni(111), and p(3 × 3)-and p(4 × 4)-Pb/Ni(111) adlayers. For the (0, 0) beam of the clean Ni(111) and for the (1/3, 1/3) and (0, 1/4) beams of the Pb/Ni(111) the dependence of diffraction spot intensity on the sample temperature was measured and the Debye temperature was determined to 370 ± 5 K, 164 ± 9 K and 180 ± 5 K, respectively.

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“…This value is also significantly larger that the 0.2 Å found in the earlier low-energy ion scattering study. 3 While this provides strong evidence that this smaller rumpling value is probably inaccurate, an even more significant conclusion that the LEED results give is that the rumpling amplitude is much less that the value of 1.67 Å predicted by a simple hard-sphere model based on bulk metallic radii. As such this confirms the earlier finding of a strong reduction in the effective radii, which may be attributed to the influence of surface valence electron charge smoothing and the associated surface stress effects.…”

mentioning

confidence: 84%

“…2 One system for which this effect appears to be especially large is the Ni(111)()ϫ))R30°-Pb surface formed by 0.33 ML of Pb on Ni͑111͒. A structural investigation of this surface was made by low-energy ion scattering 3 and reached the conclusions that the Pb atoms did occupy substitutional sites as opposed to overlayer sites, and that the surface alloy rumpling had an amplitude of 0.2 Å, with the Pb atoms higher above the underlying substrate. The authors of this paper made no comment on this value, which, as shown below, is surprisingly small.…”

mentioning

confidence: 99%

Tensor LEED analysis of theNi(111)(3×3)R30°−Pb
Quinn
¹
,
Bittencourt
²
,
Woodruff
³

2002
Phys. Rev. B
30
2
5
0
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The structure of the Ni(111)()ϫ))R30°-Pb surface has been determined by quantitative low-energy electron diffraction ͑LEED͒, using multiple-scattering simulations of the measured diffracted beam intensities with a tensor-LEED program. The results confirm that the surface comprises a single-layer substitutional alloy of stoichiometry Ni 2 Pb ͑with all atoms in ''fcc'' sites relative to the underlying Ni͒ and clearly excludes a surface/subsurface stacking fault ͑with occupation of ''hcp'' sites͒ like that found for similar phases of Sb on Cu͑111͒ and Ag͑111͒. Within the surface alloy layer the Pb atoms are 0.73Ϯ0.05-Å higher above the surface than the surrounding Ni atoms in the alloy layer. This magnitude of rumpling is in excellent agreement with a recent medium-energy ion scattering investigation of this surface, but is significantly larger than that of an earlier low-energy ion scattering investigation. Compared to the rumpling amplitude of 1.67 Å expected from a simple hard-sphere model based on bulk metallic radii, however, it confirms a strong reduction of the effective atomic radii in this surface alloy.There are now many examples of the observation that the deposition on metal surfaces of atoms in the submonolayer coverage range can lead to these adsorbate atoms occupying substitutional sites in the outermost atomic layer to produce a single-layer surface alloy. 1 This can even occur for some adsorbate/substrate element combinations immiscible in the bulk, reflecting the different energetics of the surface. One question that has attracted some interest in these systems is what the role of effective atomic radii of the adsorbate atoms is in these surface alloys, which determines the degree of ''rumpling'' of the alloy layer. If the deposited atoms have larger atomic radii than that of the substrate atoms they replace, then because the periodicity of the surface alloy parallel to the surface is fixed at the value of the underlying substrate ͑i.e., the surface alloy layer is pseudomorphic͒, a simple hard-sphere picture would predict that the adsorbate atoms would have a larger layer spacing relative to the underlying second layer of the substrate than that of the undisplaced outer-layer substrate atoms. This simply reflects the inability of a larger atom to be fully accommodated in the vacant site produced by the removal of a smaller substrate atom from the surface layer. Recent quantitative structure determinations of quite a number of surface alloy phases, however, indicate that the rumpling observed is almost always less than that predicted by this simple hard-sphere model, and this has been suggested to be a consequence of the valence electron depletion in the surface layer due to spillover into the vacuum, allowing the surface-layer atoms to approach one another more closely than in a bulk solid. 2 One system for which this effect appears to be especially large is the Ni(111)()ϫ))R30°-Pb surface formed by 0.33 ML of Pb on Ni͑111͒. A structural investigation of this surface was made by low-energy ion scat...

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Surface structure analysis ofNi(111)−(3×3)R30°−
Koji Umezawa
¹
,
Shigemitsu Nakanishi
²
,
Takahiro Yumura
³

et al.

Cited by 34 publications

References 17 publications

Quantum size effects on surfaces without a projected bandgap: Pb/Ni(111)

Quantum size effects on surfaces without a projected bandgap: Pb/Ni(111)

Debye temperature of the Pb layers on Ni(111)

Tensor LEED analysis of theNi(111)(3×3)R30°−Pb
Quinn
¹
,
Bittencourt
²
,
Woodruff
³

2002
Phys. Rev. B
30
2
5
0
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Surface structure analysis ofNi(111)−(3×3)R30°−Koji Umezawa1, Shigemitsu Nakanishi2, Takahiro Yumura3 et al.

Cited by 34 publications

References 17 publications

Quantum size effects on surfaces without a projected bandgap: Pb/Ni(111)

Quantum size effects on surfaces without a projected bandgap: Pb/Ni(111)

Debye temperature of the Pb layers on Ni(111)

Tensor LEED analysis of theNi(111)(3×3)R30°−PbQuinn1, Bittencourt2, Woodruff3 2002Phys. Rev. B30250View full textAdd to dashboardCite

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Surface structure analysis ofNi(111)−(3×3)R30°−
Koji Umezawa
¹
,
Shigemitsu Nakanishi
²
,
Takahiro Yumura
³

et al.

Tensor LEED analysis of theNi(111)(3×3)R30°−Pb
Quinn
¹
,
Bittencourt
²
,
Woodruff
³

2002
Phys. Rev. B
30
2
5
0
View full text Add to dashboard Cite