Berlin 2005 – scientific programme

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O: Oberflächenphysik

O 4: Epitaxie und Wachstum I

O 4.9: Talk

Friday, March 4, 2005, 12:45–13:00, TU EB202

Growth and electronic structure of ultrathin chromium films on iridium(111) investigated by scanning tunneling microscopy and spectroscopy — •Felix Marczinowski, Kirsten von Bergmann, and Roland Wiesendanger — Institut für Angewandte Physik, Universität Hamburg

Magnetic materials are showing interesting properties when prepared as thin films. Bulk Cr has bcc structure and is antiferromagnetic. Instead, if grown as a hexagonal monolayer film, the antiferromagnetic alignment of neighbouring atomic moments is impossible and a frustrated spin-structure will be formed [D. Wortmann et al., Resolving Complex Atomic-Scale Spin Structures by Spin-Polarized Scanning Tunneling Microscopy, PRL(2001)]. To study this spin-structure on an atomic level, Cr films of various coverages were deposited on an Ir(111) substrate by means of molecular beam epitaxy (MBE). The growth up to three monolayers was studied by scanning tunneling microscopy and spectroscopy. Indeed, the Cr monolayers grow pseudomorphically on the Ir(111) substrate and hence have hexagonal symmetry. Interestingly, we find a coexistence of faulted and unfaulted Cr-monolayer areas with distinct morphology and slightly different electronic properties. For higher coverages, a modified Volmer-Weber growth mode is observed. For coverages above two monolayers the Cr film relaxes towards its bulk structure and shows an epitaxial relationship according to the Kurdjumov-Sachs orientation.