Journal Article

FZJ-2017-00328

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Au enrichment and vertical relaxation of the Cu$_{3}$ Au ( 111 ) surface studied by normal-incidence x-ray standing waves

Bauer, O. ; Schmitz, C. H. ; Ikonomov, J. ; Willenbockel, M. ; Soubatch, S. ; Tautz, F. S.FZJ* ; Sokolowski, M. (Corresponding author)

2016
Inst. Woodbury, NY

This record in other databases:  

Please use a persistent id in citations: http://hdl.handle.net/2128/13425  doi:10.1103/PhysRevB.93.235429

Abstract: We have investigated the Cu3Au(111) surface, prepared under ultrahigh vacuum conditions by sputtering and annealing, by low energy electron diffraction (LEED), scanning tunneling microscopy (STM), x-ray photoelectron spectroscopy, and normal incidence x-ray standing waves (NIXSW). We find the surface to be depleted with Cu and enriched with Au at the same time, yielding a nominal Cu:Au ratio of 0.61:0.39 in the topmost layer. The STM images reveal that the first layer is nearly closely filled with atoms and contains a small amount of vacancies with an area concentration of about 5%. Together with the Au enrichment, these cause local short-range disorder of the Au p(2×2) reconstruction. From this data, the average stoichiometry of the p(2×2) surface unit cell is estimated at Cu2.22Au1.44□0.20 (instead of Cu3.00Au1.00□0.00 of the ideal surface; □ denotes an atomic vacancy site). From NIXSW we find a significant outward relaxation of both the Cu and Au atoms of the topmost layer by 0.28 Å and 0.33 Å, which corresponds to 13% and 15% of the (111) bulk layer spacing of Cu3Au. We suggest that this originates from a widening of the first/second layer spacing, by 6.8% and 8.8% for the Cu and Au atoms, respectively, plus an additional rigid increase in the second/third layer spacing by 6.2%. We explain this by steric repulsions between Au atoms of the topmost layer, replacing smaller Cu atoms, and Au atoms in the second layer in combination with disorder. Finally, a lateral reconstruction, similar to that on the Au(111) surface, but with a much larger periodicity of 290 Å, is identified from LEED.

---

Contributing Institute(s):

1. Funktionale Nanostrukturen an Oberflächen (PGI-3)

Research Program(s):

1. 142 - Controlling Spin-Based Phenomena (POF3-142) (POF3-142)

Appears in the scientific report 2016

---

Database coverage:
; ; ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

---