Berlin 2008 – scientific programme
Parts | Days | Selection | Search | Downloads | Help
O: Fachverband Oberflächenphysik
O 89: Metal Substrates: Epitaxy and Growth
O 89.2: Talk
Friday, February 29, 2008, 09:45–10:00, MA 041
The buried Ni/Cu(001) interface at the atomic scale — •Holger L. Meyerheim1, Dirk Sander1, Nikolay Negulyaev1, Valeri S. Stepanyuk1, Radian Popescu1, Iona Popa2, and Jürgen Kirschner1 — 1MPI-Halle, Weinberg 2, D-06120 Halle (Germany) — 2ESRF, BP 220, F-38043 Grenoble (France)
We present a combined surface x-ray diffraction and theoretical analysis of the buried Ni/Cu(001) interface structure after deposition of 3 and 5 monolayers of Ni at room temperature. Highly accurate reflection intensities along the integer order crystal truncation rods were collected at the beamline ID3 of the ESRF in Grenoble (France). The analysis reveals interface mixing where 27±10% of top layer Cu-atoms are exchanged by Ni. In addition, a 0.13 Å inward relaxation of top layer Ni-atoms is determined. Atomic scale simulations reveal a kinetic pathway for the Ni/Cu-exchange process and explain the observed limited degree of intermixing. A disperse distribution of Ni within the Cu surface with a preferential Ni-Ni separation of 3-4 nearest neighbor distances is found [activation energy for exchange (Eb) equal to 0.65 eV]. Intermixing is spatially confined to two atomic layers adjacent to the interface in agreement with experiment. The calculations also provide an explanation for the markedly different behavior of intermixing reported for Fe-Cu(001)interface, where Fe forms embedded clusters in the Cu surface [1].
[1] D.D. Chambliss and K.E. Johnson, Phys, Rev. B 50, 5012 (1993)