Münster 1997 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

O: Oberflächenphysik

O 23: Diffusion/Wachstum auf Metallen

O 23.4: Vortrag

Mittwoch, 19. März 1997, 16:45–17:00, S 10

Surface stress and elastic energy in thin films — •Paola Alippi and Matthias Scheffler — Fritz-Haber-Institut der MPG,Faradayweg 4-6,D-14195 Berlin-Dahlem

In recent experiments [1], the stress of a Ag film grown on a Pt(111) substrate was found to largely (i.e., by an order of magnitude) exceed the value predicted by elasticity theory: the film substains this large stress, growing up to 8 monolayers at room temperature, while the effect disappers then upon annealing. The origin of the observed large stress in the strained Ag film has not yet been fully investigated.

We have performed total energy calculations for the Ag/Pt(111) system using density functional theory and the LAPW method, and obtained the surface stress of the slab from the calculated energies of the relaxed geometries. The method was also recently employed [2] to study the stability of epitaxial films, and to discuss the validity range of linear elasticity theory.

We analyse the nature of the chemical bond of Ag at the Pt surface and discuss how the bond formation and partial charge transfer may affect the surface stress of the Pt(111) substrate.

[1] A. Grossmann, W. Erley, J.B. Hannon, H. Ibach, PRL 77, 127 (1996).

[2] P. Alippi, P.M. Marcus, M. Scheffler, submitted to Phys. Rev. Lett.