Dresden 2009 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 14: Poster Ib: Magnetic Materials (1-14); Micro Magnetism/Computational Mag. (15-17); Surface Magnetism (18-22); Spin Structures/Phase Transitions (23-25)

MA 14.19: Poster

Dienstag, 24. März 2009, 10:15–13:00, P1B

Delayed phase transition from fcc(111) to bcc(110) for Fe on vicinal Au(111) — •Tobias Allmers and Markus Donath — Physikalisches Institut, Universität Münster, 48149 Münster

Vicinal surfaces offer the opportunity for the fabrication of a regular array of nanostructures and for studying the influence of a reduced symmetry. The morphology and the magnetism of Fe films on flat Au(111) were already thoroughly investigated by various groups [1,2]. At a certain film thickness a phase transition from Fe fcc(111) to bcc(110) was identified, accompanied by a spin reorientation transition from out-of-plane to in-plane. We used Fe on vicinal Au(111), in our case Au(23 25 25), to study the influence of the modified substrate topography on the growth mode and the resulting magnetic properties. For thicknesses beyond the phase transition, the pseudomorphic growth of Fe is disrupted and rectangular structures appear. The orientation and development of these structures is different on the flat and the vicinal surface. Our results obtained with scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and magneto-optical Kerr effect provide a consistent picture. Different from Fe on flat Au(111), the phase transition from fcc(111) to bcc(110) occurs at a higher Fe coverage on vicinal Au(111). We present a structural model for the phase transition of Fe on Au(23 25 25), which explains the observed differences in the development and orientation of the rectangular structures as observed in STM and LEED.

[1] Strosio et al., J. Vac. Sci. and Technol. A 10, 1981 (1992)

[2] Lugert et al., J. Magn. Magn. Mater. 121, 498 (1993)