IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Monday Sessions
       Session SS2-MoM

Paper SS2-MoM1
Mesoscopic Strain-Induced Magic Fe Nanostructures on Cu(100)

Monday, October 29, 2001, 9:40 am, Room 121

Session: Metal Clusters
Presenter: J.V. Barth, EPFL, Switzerland
Authors: N. Lin, Max-Planck-Institut for Solid State Physics, Stuttgart, Germany
A. Dmitriev, Max-Planck-Institut for Solid State Physics, Stuttgart, Germany
V.S. Stepanyuk, Martin-Luther-University, Germany
D.I. Bazhanov, Martin-Luther-University, Germany
J. Weckesser, Max-Planck-Institut for Solid State Physics, Stuttgart, Germany
J.V. Barth, EPFL, Switzerland
K. Kern, Max-Planck-Institut for Solid State Physics, Stuttgart, Germany and EPFL, Switzerland
Correspondent: Click to Email
We report a novel phenomenon in metal-on-metal heteroepitaxy, expressed in the arrangement of Fe islands grown at low temperature (<200K) on a Cu(100) surface. Scanning tunneling microscopy observations reveal that Fe atoms aggregate as perfectly oriented well-defined nanometer-scale arrays when Fe-Cu exchanging is inhibited. The basic unit of these nanoarrays is a tetramer of Fe atoms. More than 60 percent of the nanoarrays consist of four tetramers arranged in a square shape, aligning exactly to the high symmety directions of the Cu(100). The sharp distribution and distinct shapes of the nanoarrys can be understood in the framework of mesoscopic strain. STM and first principle calculations demonstrate that both the Fe isalnds and Cu substrate experience a large relaxation due to the mesoscopic strain: the Fe interatomic distance in the tetramers (2.0 Å) is 20% less than that in thin fcc Fe/Cu(100) films (2.5 Å), and the Cu substrate underneath the Fe nanoarrays is compressed 16.4% relative to the unrelaxed Cu surface (2.56 Å) . The giant compression and the high stress energy promote the formation of super-compressed Fe tetramers and their aggregation as magic nanoarrays with regular shape and orientation.