Berlin 2008 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 7: Micro and Nanostructured Magnetic Materials II
MA 7.1: Vortrag
Montag, 25. Februar 2008, 15:15–15:30, EB 301
The Effect of Step Atoms on the Switching Behavior of Superparamagnetic Nanoislands — •Gabriela Herzog1, Stefan Krause1, Matthias Bode2, and Roland Wiesendanger1 — 1Institute of Applied Physics, University of Hamburg, Germany — 2Center for Nanoscale Materials, Argonne National Laboratory, USA
Spin-polarized scanning tunneling microscopy (SP-STM) is a well-established tool to investigate not only static but also dynamic magnetic properties at lateral resolution down to the atomic scale [1]. Our variable temperature STM is suitable to investigate the superparamagnetic switching behavior of single nanoislands consisting of about 100 Fe atoms on W(110) over a wide temperature range between 30 K and 50 K.
From the Arrhenius-like switching behavior we can derive the anisotropy energy barrier that has to be surmounted by thermal agitation to switch the magnetization of a particular nanoisland. An analysis of the data reveals that the energy barrier is neither in agreement with a coherent switching, nor a switching by the nucleation of a domain wall.
Recently, it has been shown that the anisotropy of edge and center atoms of Co islands on Pt(111) varies by more than one order of magnitude due to different coordination [2]. Our experimental results will be presented and discussed in terms of anisotropy contributions in dependence of atom coordination number.
[1] M. Bode et al., Phys. Rev. Lett. 92, 067201 (2004)
[2] S. Rusponi et al., Nature Mater. 2, 546 (2003)