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MA: Fachverband Magnetismus

MA 12: Magnetic Particles/ Clusters II

MA 12.9: Vortrag

Montag, 14. März 2011, 19:00–19:15, HSZ 103

Revealing the magnetization reversal mechanism - from coherent rotation in compact to domain wall propagation in fractal islands — •Alberto Cavallin¹, Fabian Natterer¹, Safia Ouazi¹, Géraud Moulas¹, Anne Lehnert¹, Stefano Rusponi¹, Stanislas Rohart², Wulf Wulfhekel³, and Harald Brune¹ — ¹IPMC, École Polytechnique Fédérale de Lausanne (EPFL), Station 3-B, CH-1015 Lausanne — ²Laboratoire de Physique des Solides, Université Paris XI et CNRS, F-91405 Orsay — ³Physikalisches Institut, Universität Karlsruhe (TH), D-76131 Karlsruhe

Magnetic nanostructures grown by self-assembly at surfaces are ideal model systems to explore the ultimate density limit of magnetic recording. While is it generally accepted that the magnetic ground state of nanostructures with a size of a few thousand atoms or less is monodomain, i.e., all spins are ferromagnetically aligned to a single domain, the transition state reached upon thermally activated magnetization reversal as a function of the island size and shape is debated [1,2]. This state lasts only ps and there are no techniques to image it at this time scale with the required spatial resolution of sub-nm. Therefore it can only be inferred indirectly. Our combined magneto-optical Kerr effect (MOKE) and STM measurements reveal for Co islands on Pt(111) a shape-dependent transition from the coherent rotation of all spins to the nucleation and propagation of a domain wall, going from compact to fractal islands.

References: [1] M. Bode et al. PRL 92 067201 (2004)

[2] S. Krause et al. PRL 103 127202 (2009)