Regensburg 2004 – wissenschaftliches Programm
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O: Oberflächenphysik
O 3: Nanostrukturen I
O 3.8: Vortrag
Montag, 8. März 2004, 13:00–13:15, H36
Lateral Ir-spaced superlattices of Fe, Co and Ni on Ir(100) — •Andreas Schmidt, Andreas Klein, Chiara Giovanardi, Lutz Hammer, and Klaus Heinz — Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstr. 7, D-91058 Erlangen
The stable phase of Ir(100) exhibits a quasi-hexagonal top layer with six atomic rows fitting to five rows of the second layer (Ir(100)-(5× 1)-hex). Exposure to hydrogen lifts this reconstruction by expelling the 20% extra atoms accommodated in the top layer to the very surface. This Ir(100)-(5×1)-H phase is characterized by monoatomic, almost defect free Ir wires of up to micrometer length which reside in 5×1 long-range order on the unreconstructed substrate. By deposition of Fe, Co or Ni the space between these wires can be filled, whereby the three elements differ by their growth modes as is observed by scanning tunnelling microscopy (STM). For e.g. Fe, deposition the final state at 0.8 ML coverage corresponds to a lateral superlattice, {Fe4Ir}. Its crystallographic structure as determined by the measurement and quantitative dynamical analysis of low-energy electron diffraction (LEED) intensities is reported. When iron is deposited on Ir(100)-(5×1)-hex rather than on Ir(100)-(5×1)-H), locally the same Fe4Ir surface compound results, yet with a considerably lower degree of long-range order.