Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 55: Poster Session III - MA 141/144 (Methods: Atomic and Electronic Structure; Particles and Clusters; Heterogeneous Catalysis; Semiconductor Substrates: Epitaxy and Growth+Adsorption+Clean Surfaces+Solid-Liquid Interfaces; Oxides and Insulators: Solid-Liquid Interfaces+Epitaxy and Growth; Phase Transitions; Metal Substrates: Adsorption of Inorganic Molecules+Epitaxy and Growth; Surface Chemical Reactions; Bimetallic Nanosystems: Tuning Physical and Chemical Properties; Oxides and insulators: Adsorption; Organic, polymeric, biomolecular films; etc.)
O 55.46: Poster
Mittwoch, 27. Februar 2008, 18:30–19:30, Poster F
STM observation of antiphase boundaries in Fe3O4(001)/MgO thin epitaxial films — •David Serrate1, Julia M. Orna2, Luis Morellón2, Andre Kubetzka1, Kirsten von Bergman1, and Roland Wiesendanger1 — 1Institute of Applied Physics, University of Hamburg, Hamburg, Germany — 2Instituto de Nanociencia de Aragón, University of Zaragoza, Zaragoza, Spain
Due to its high Curie temperature and half-metallic nature, Fe3O4 thin films are archetypal candidates as electrodes for spin-valve type devices. However, the spin filtering effects achieved at room temperature up to date are modest1. The reason is that the properties of the Fe3O4 surface play a mayor role on the TMR of magnetic tunnel junctions, and therefore a better understanding of the surface termination is mandatory. Several STM experiments have been published on the (001) surface of bulk single crystals, but the surface of artificial thin films remains unexplored. The most likely defects occurring in Fe3O4 epitaxial films are the so-called antiphase boundaries (APB)2, which arise from the coalescence of two crystallographic domains. We report the direct observation of APB in thin epitaxial Fe3O4 (40 nm) by means of STM topography showing atomic resolution. Fe3O4(001) was grown on MgO(001) by pulsed laser deposition. Surface preparation for STM measurements consisted of cycles of Ar+ etching and O2 annealing at 5×10−7 mbar. The results provide a structural model for the APB and confirm the origin of the in-plane MR characteristic of ultrathin Fe3O4 films2. [1] H. Matsuda et al., Jpn. J. Appl. Phys. 41, L387 (2002) [2] W. Eerestein et al., Phys. Rev. Lett. 88, 247204 (2002)