|AVS 54th International Symposium|
|Surface Science||Tuesday Sessions|
|Session:||Surface Science Poster Session|
|Presenter:||S.S. Parihar, University of Wisconsin-Milwaukee|
|Authors:||P.F. Lyman, University of Wisconsin-Milwaukee
S.S. Parihar, University of Wisconsin-Milwaukee
|Correspondent:||Click to Email|
Subsurface alloying is an interesting phenomenon that has been observed for several transition metals deposited on noble-metal surfaces, even where there is no bulk solubility of the two metals. In particular, while the bulk phase diagram of Ir-Cu has a large miscibility gap, subsurface alloying has been observed for Ir/Cu(100).1,2 The Ir atoms appear to occupy ordered subsurface sites, forming a (2x1) reconstruction, with the required atomic place exchange taking place even for deposition at 200 K.1 In the second layer, Ir and Cu atoms form Ir-Ir and Cu-Cu chains along every other close-packed direction. We evaporated submonolayer to monolayer Ir films on clean Cu(110) surfaces, and investigated the Ir-induced reconstruction using low energy electron diffraction (LEED) and x-ray photoelectron spectroscopy (XPS). The (1x1) LEED pattern changes into a (2x1) pattern for Ir coverages of close to half a monolayer. We expect that the Ir will still be confined to the near-surface region by the lack of bulk solubility, and we hypothesize that the Ir atoms will occupy subsurface sites based on their behavior on Cu(100). Based on LEED and XPS results, we propose that Cu and Ir form Ir-Cu-Ir-Cu chains along the close-packed direction for Ir/Cu(110)-(2x1), in contrast to the finding for Ir/Cu(100)-(2x1).
1S. Heinze, R. Abt, S. Blügel, G. Gilarowski, and H. Niehus, Phys. Rev. Lett. 83, 4808-4811 (1999).
2G. Gilarowski and H. Niehus, Surf. Sci. 436, 107-120 (1999).