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Suppression of disorder broadening of core-level photoelectron lines in CuAu alloys by inhomogeneous lattice distortion
Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
Kyoto University.
Uppsala University.
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2009 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 79, no 1, 012201- p.Article in journal (Refereed) Published
Abstract [en]

Disorder broadening of core-level binding energies is a general effect observed in random alloys, and identifies an opportunity for studying specific local environments experimentally. Here we study it in an archetypical system: face-centered-cubic Cu50Au50. While the disorder broadening is clearly detectable at Au, at Cu it is below the detection limit. We supplement experiments by a theoretical study where we model the alloy by a large supercell constructed as a special quasirandom structure and calculate binding-energy shifts at all sites in the supercell. Theory shows that the suppression of the disorder broadening at Cu results from a delicate balance between the influence of local chemical environment and inhomogeneous lattice distortions on the site-resolved core-level shifts. Surprisingly, even larger relaxation-induced shifts are observed at Au sites.

Place, publisher, year, edition, pages
2009. Vol. 79, no 1, 012201- p.
Keyword [en]
copper alloys, core levels, electronic structure, gold alloys, photoelectron spectra
National Category
Natural Sciences
URN: urn:nbn:se:liu:diva-16832DOI: 10.1103/PhysRevB.79.012201OAI: diva2:174374
Available from: 2009-02-21 Created: 2009-02-20 Last updated: 2010-12-27Bibliographically approved
In thesis
1. Theoretical Considerations of Local Environment Effects in Alloys
Open this publication in new window or tab >>Theoretical Considerations of Local Environment Effects in Alloys
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis is devoted to a theoretical study of local environment effects in alloys. A fundamental property of a disordered system is that all chemically equivalent atoms are different due to their different chemical environments, in contrast to an ideal periodic solid where all the atoms that occupy equivalent positions in the crystal have exactly the same physical properties. The local environment effects have been largely ignored in earlier theories of disordered systems, that is the system has been treated as a whole and average properties have been derived. Moreover, inhomogeneous systems, such as surfaces and interfaces, induce local environment effects that are not necessarily present in the bulk.

The importance and presence of local environment effects are illustrated by calculating observable physical properties in various systems. In particular, by employing the complete screening picture the effects of local environments on the core-level binding energy shifts as well as Auger shifts in random alloys are in- vestigated. This so-called disorder broadening effect has recently been observed experimentally. It is shown that there are different contributions to the disorder broadening that vary with the local chemical environment. Furthermore, the influ- ence of inhomogeneous lattice distortions on the disorder broadening of the core- level photoemission spectra are considered for systems with large size-mismatch between the alloy components.

The effects of local chemical environments on physical properties in magnetic systems are illuminated. A noticeable variation in the electronic structure, local magnetic moments and exchange parameters at different sites is obtained. This reflects the sensitivity to different chemical environments and it is shown to be of qualitative importance in the vicinity of magnetic instability.

The local environment effects due to the presence of surfaces and interfaces are also considered. The effect is explicitly studied by considering the concentration profile of a thin Ag-Pd film deposited on a Ru substrate. Two computational approaches are utilized to calculate the relative composition in each layer of the thin film as a function of temperature in a theoretically consistent way. It is shown that, opposed to the situation in the bulk, where a complete solubility between Ag and Pd takes place, a non-uniform distribution of the alloy components across the film is observed.

In another study it is investigated whether the presence of TiN interfaces changes the dynamical and thermodynamic stability of B1 SiN. Phonon calcula- tions show that TiN interfaces have a stabilization effect on the lattice dynamics. On the other hand, calculations of the Si vacancy formation energy show that the structures are unstable with respect to composition variations.


Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2010. 86 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1353
National Category
Condensed Matter Physics
urn:nbn:se:liu:diva-63443 (URN)978-91-7393-285-1 (ISBN)
Public defence
2010-12-17, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Available from: 2010-12-27 Created: 2010-12-19 Last updated: 2010-12-27Bibliographically approved

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Marten, TobiasAbrikosov, Igor
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