On a “surfactant-like” behaviour of deposit

Aufray, B.; Giordano, H.; Legrand, Bernard; Tréglia, G.

doi:10.1016/0039-6028(94)90449-9

Cited by 29 publications

(7 citation statements)

References 17 publications

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“…Both experiments and simulations showed in fact for the Ni/Ag͑001͒ interface a ''surfactantlike'' behavior that consists of the formation of layers or clusters of Ni buried below some Ag floating monolayers. [30][31][32] A similar effect has been observed for different metals like Rh ͑Ref. 33͒, Cr ͑Ref.…”

Section: Resultssupporting

confidence: 56%

Oxygen-dosage effect on the structure and composition of ultrathin NiO layers reactively grown on Ag(001)

Giovanardi¹,

Bona²,

Valeri

2004

Phys. Rev. B

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NiO ultrathin films have been prepared under UHV conditions on Ag͑001͒ substrate by metal deposition in O 2 atmosphere. The films were prepared by deposition of the amount of metal correspondent to 1 ML ͑mono-layer͒ of NiO in the presence of different oxygen-to-metal flux ratios, to investigate the oxygen dosage effect on the structure and composition of the growing layer and on the stoichiometry of Ni oxide. Thicker films ͑up to 20 ML͒ were also prepared. The structure has been monitored both in reciprocal and direct space by low-energy electron diffraction and primary-beam diffraction-modulated electron emission. Core-level x-ray photoemission spectroscopy has been used to study film chemistry and composition. At low coverage ͑below 2 ML͒ a dramatic dependence of structure and composition on the oxygen-to-nickel flux ratio has been observed. Low oxygen dosage induces a (2ϫ1) reconstruction in the 1-ML films that evolves to a (1ϫ1) phase as the dosage and/or the film thickness increases. In the layers prepared at low oxygen dosage a large fraction of metallic Ni coexists with the Ni oxide, but the oxidized fraction largely prevails for high oxygen dosage. The oxygen dosage during the growth also affects thicker films. The mosaic formation, which has been ascribed to misfit strain relaxation, is related to a low oxygen-to-nickel flux ratio.

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Section: Resultssupporting

confidence: 56%

Oxygen-dosage effect on the structure and composition of ultrathin NiO layers reactively grown on Ag(001)

Giovanardi¹,

Bona²,

Valeri

2004

Phys. Rev. B

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“…In case of tendency to A/B phase separation, dissolution paths will critically depend on the A and B surface energies. The case of interest here, in which B atoms show a stronger tendency to surface segregation than A atoms as for Fe/Ag or Ni/Ag systems, 19 was illustrated in Ref. The excellent agreement between data of figs.…”

Section: 18supporting

confidence: 61%

Surfactant effect and dissolution of ultrathinFefilms onAg(001)

Terreni¹,

Cossaro

Gonella³

et al. 2004

Phys. Rev. B

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The effects of annealing on the structure of ultra thin Fe films (4 -10 ML) deposited at 150 K on Ag(001) were studied by synchrotron radiation photoelectron diffraction (PED) and x-ray diffraction (XRD). The occurrence of a surfactant-like stage, in which a single layer of Ag covers the Fe film is demonstrated for films of 4-6 ML heated at 500-550 K. Evidence of a stage characterized by the formation of two Ag capping layers is also reported. As the annealing temperature was increased beyond 700 K the surface layers closely resembled the structure of bare Ag(001) with the residual presence of subsurface Fe aggregates. The data illustrate a film dissolution path which is in agreement with recent theoretical models [J. Roussel et al. Phys. Rev. B 60, 13890 (1999)].PACS numbers: 68.35.-p, 68.55.-a The phase immiscibility and the excellent matching between Ag(001) and Fe(001) unit cells (mismatch 0.8 %) make Fe/Ag growth attractive in the field of low dimensionality magnetic systems, such as ultrathin films, 1 multilayers, 2 and small aggregates 3 . At the nanometric scale, atomic exchange processes were found to affect the chemical sharpness of interfaces in films and multilayers.4 Intermixing could be drastically limited at deposition temperatures as low as 140-150 K 4,5,6 at the expense of a poor morphological quality of the film. 7,8The film structural evolution induced by post-growth annealing presents many interesting aspects involving activated atomic exchange processes and affecting magnetic properties.9 Previous experiments, of He and low energy ion scattering on films deposited at 150 K, indicated the formation of a segregated Ag layer upon moderate annealing (550 K). Higher temperatures led to the embedding of Fe into the Ag matrix.10 In those experiments, information on sub-surface layers was attained by ion erosion depth profiling, a destructive technique mainly sensitive to the topmost layer. Many questions remained open about the film structure and morphology evolution during dissolution. Here we address this issue by presenting photoelectron and x-ray diffraction experiments, performed at the ALOISA beam line (ELETTRA, Trieste). PED provides chemically selected data on film structure with an information depth of several layers. It allows to characterize local order in films which are disordered on a long range scale and possesses specific sensitivity to segregation processes.11 Systematic PED measurements have been accompanied with a few XRD rod scans yielding a better sensitivity to the buried interface and the film long range order. The results of this paper allow a comparison with recent models enlightening the dissolution paths of an ultra thin metal film into a different metal, when both subsurface migration of the deposit and phase separation between substrate and deposit are favoured. 17,18Details on the ALOISA system can be found elsewhere.12 The Ag substrate was prepared according to well established procedures.7 Reflection High Energy Electron Diffraction was used to monitor the surfa...

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“…A specific example is the case of a metal grown on a single crystalline substrate of much lower surface energy than itself. One monolayer of Ni deposited on Ag(111) or Ag(100), in particular, becomes covered by one or two layers of Ag upon annealing to 770 and 620 K, respectively [1,2]. Theoretical calculations [2][3][4] predict, moreover, that these capping layers remain on top during further deposition.…”

mentioning

confidence: 99%

“…One monolayer of Ni deposited on Ag(111) or Ag(100), in particular, becomes covered by one or two layers of Ag upon annealing to 770 and 620 K, respectively [1,2]. Theoretical calculations [2][3][4] predict, moreover, that these capping layers remain on top during further deposition. Monte Carlo simulations [5] show that a Ni monolayer upon annealing to 620 K spreads over six to seven subsurface layers in the form of clusters with (111) and (100) facets which contain about 100 atoms.…”

mentioning

confidence: 99%

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Burrowing of Co Nanoparticles on Clean Cu and Ag Surfaces

et al. 1999

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Metal nanoparticles can display a unique behavior when deposited on substrates with a significantly lower surface energy. Co nanoparticles in the 10 nm size regime burrow into clean Cu(100) and Ag(100) substrates when deposited at 600 K and also assume the substrate orientation. Deposition at room temperature fails to show either burrowing or reorientation. Crucial in understanding these results are the capillary forces and surface tension associated with a nanoparticle: they must be high enough to drive atoms away from underneath the cluster.

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On a “surfactant-like” behaviour of deposit

Cited by 29 publications

References 17 publications

Oxygen-dosage effect on the structure and composition of ultrathin NiO layers reactively grown on Ag(001)

Oxygen-dosage effect on the structure and composition of ultrathin NiO layers reactively grown on Ag(001)

Surfactant effect and dissolution of ultrathinFefilms onAg(001)

Burrowing of Co Nanoparticles on Clean Cu and Ag Surfaces

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