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 55.64: Poster

Mittwoch, 27. Februar 2008, 18:30–19:30, Poster F

The growth of Co on Fe/W(110)investigated by STM and STS — •Torsten Methfessel and Hans-Joachim Elmers — Johannes Gutenberg-Universität Mainz, Institut für Physik, Staudingerweg 7, D-55099 Mainz

Highly spinpolarised metals are of great interest e.g. for the application in spin-valves. Recently observed large tunneling magnetoresistance (TMR) effect values of 410 % at room temperature for Co/Fe(100) electrodes indicate a high spin-polarisation at the Fermi energy of bcc Co [1]. Instead of a (100) oriented substrate, we grow bcc Co on Fe(110), where the symmetry change from hcp to bcc becomes obvious in the (110) surface plane, in contrast to the (100) orientation. In order to prepare a Fe(110) substrate, we deposited a 8 ML Fe film on W(110) that was annealed to 500 K. The annealing results in large separated islands with an ideal Fe(110) surface, that serves as a substrate for the deposition of Co. Using scanning tunneling microscopy and spectroscopy (STM and STS) we investigated the local structural and electronic properties of the bcc Co films. The first monolayers of Co grow as pseudomorphic bcc layers, which shows periodic lattice distortions similar to the growth of Co on Cr(110) [2]. Single point spectroscopy reveals a peak of the LDOS at +1 eV in contrast to the peak at +0.6 eV observed for the second monolayer bcc Co/Cr(110), which might be explained by the differences in the lattice constants of Fe and Cr.

[1] S. Yuasa et al., Appl.Phys.Lett. 89 (2006) 042505.

[2] T. Methfessel et al., Suf.Sci. 601 (2007) 5026.