Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 32: Epitaxie und Wachstum II

O 32.11: Vortrag

Donnerstag, 27. März 2003, 17:30–17:45, FOE/ANOR

Mn-induced stress during surface alloy formation on Cu(001) — •Wei Pan, D. Sander, and J. Kirschner — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle

We have performed combined stress and low energy electron diffraction (LEED) measurements during the deposition of Mn on Cu(100) at temperatures between 150 K and 420 K. Deposition of Mn at room temperature and above leads to the formation of the well known c(2x2) surface alloy for a Mn surface coverage of 0.5 [1]. This structure is characterized by a compressive stress of -1.1 N/m. Further deposition at 320 K of up to 2 layers Mn does not change this stress state significantly, and no other surface structure is observed by LEED. Deposition at 420 K also leads to the c(2x2) structure at the coverage 0.5 with a stress of -1.0  N/m, but additional deposition leads to the formation of the p2mg structure, which is characterized by a total compressive stress of -2 N/m for 2 layers Mn coverage. The compressive stress measured for the surface alloy formation can be qualitatively ascribed to the larger atomic diameter of Mn as compared to Cu. Mn deposition at low temperature does not induce any surface stress change for a coverage of up to 0.5, although LEED indicates the formation of an ordered c(8x2) structure. This stress-free growth is unexpected and it suggests competing stress mechanisms, which will be discussed.

[1] M. Wuttig, Y. Gauthier, S. Blügel, Phys. Rev. Lett. 70(1993)3619.