Double-segregation effect in AgxPd1-x/Ru(0001) thin film nanostructures

We study the structural properties of ultrathin AgxPd1-x films on top of a Ru(0001) substrate. Effective interatomic interactions, obtained from first-principles calculations, have been used in Monte Carlo simulations to derive the distribution of the alloy components in a four-monolayer (4-ML) Ag-P...

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Bibliographic Details
Published in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2008-03, Vol.77 (12)
Main Authors: Marten, T., Hellman, O., Ruban, Andrei V., Olovsson, W., Kramer, C., Godowski, J. P., Bech, L., Li, Z. S., Onsgaard, J., Abrikosov, I. A.
Format: Article
Language:English
Subjects:
1st-principles
coherent-potential approximation
cu-ni
energy
segregation
stability
surface
transition-metal alloys
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Summary:We study the structural properties of ultrathin AgxPd1-x films on top of a Ru(0001) substrate. Effective interatomic interactions, obtained from first-principles calculations, have been used in Monte Carlo simulations to derive the distribution of the alloy components in a four-monolayer (4-ML) Ag-Pd film. Though Ag-Pd alloys show complete solubility in the bulk, the thin film geometry leads to a pronounced segregation between Ag and Pd atoms with a strong preference of Ag atoms toward the surface and Pd atoms toward the interface. The theoretical prediction of this double-segregation effect is strongly supported by photoelectron spectroscopy experiments carried out for 4-ML thin films. We also show, in an additional experiment, that even in the case where initially 1 ML Ag is buried under 6 ML Pd, the whole Ag ML segregates to the surface.
ISSN:1550-235X
1098-0121
DOI:10.1103/PhysRevB.77.125406