Regensburg 2013 – scientific programme
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O: Fachverband Oberflächenphysik
O 35: Poster Session I (Metal, semiconductor and oxide substrates: structure and adsorbates; Graphene)
O 35.62: Poster
Tuesday, March 12, 2013, 18:15–21:45, Poster B1
Magnetic properties of ultrathin iron oxide films on MgO(001), grown in oxygen atmosphere — •Nico Pathé1, Tobias Schemme1, Timo Kuschel2, and Joachim Wollschläger1 — 1Fachbereich Physik, Universität Osnabrück, Barbarastr. 7, 49076 Osnabrück — 2Fakultät für Physik, Universität Bielefeld, Universitätsstrasse 25, 33615 Bielefeld
Due to its characteristics in Giant Magneto Resistance (GMR), iron oxides can be used in magnetoresistive memory devices. In this work, ultrathin iron oxide films were reactively grown on MgO(001) at 250∘C. Therefore, the oxygen partial pressure was increased from 5·10−7 mbar to 5·10−4 mbar. Since this has a strong influence on the stoichiometry, the films were charakterized by X-Rax Photoelectron Spectroscopy (XPS). The surface structures were studied by Low Energy Electron Diffraction (LEED) and the magnetic properties of the films were investigated via Magneto-Optic Kerr Effect (MOKE). The XPS data shows that there’s still elemental Fe at the surface after preparation in 5·10−7 mbar O2. For oxygen partial pressures of 5·10−6 mbar and above only Fe2+ and Fe3+ ions can be found on the surface. Just between 5·10−6 mbar and 5·10−5 mbar Fe3O4 is formed at the surface. This is confirmed by LEED measurements, which show the expected (√2×√2)R45∘ superstructure for these films. MOKE reveals, that the films grown at an oxygen partial pressure of 5·10−7 mbar and 5·10−5 mbar have a fourfold magnetic anisotropy. The easy axes are aligned in Fe3 O4 [110] direction.