Dresden 2011 – scientific programme

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MA: Fachverband Magnetismus

MA 63: Poster II (Surface Magnetism/ Magnetic Imaging/ Topological Insulators/ Spin Structures and Magnetic Phase Transitions/ Graphene/ Magnetic Thin Films/ Magnetic Semiconductors/ Magnetic Half-metals and Oxides/ Spin-dependent Transport/ Spin Excitations and Spin Torque/ Spin Injection and Spin Currents in Heterostructures/ Spintronics/ Magnetic Storage and Applications)

MA 63.9: Poster

Friday, March 18, 2011, 11:00–14:00, P2

Thermal magnetization reversal of small Fe-nanoislands on W(110) — •Andreas Sonntag, Anika Schlenhoff, Gabriela Herzog, Stefan Krause, and Roland Wiesendanger — Institute of Applied Physics, University of Hamburg, Germany

Spin-polarized scanning tunneling microscopy (SP-STM) has been proven to be a powerful technique for investigating magnetic nanostructures [1]. Recently it has been applied to probe the thermal switching behavior of superparamagnetic Fe/W(110) nanoislands [2]. It turned out that the magnetization reversal of islands that consist of more than approx. 30 atoms takes place via the nucleation and propagation of a domain wall. The smallest island investigated in the study showed a significantly different behavior which could not be explained within this model.

In our experiments we studied very small iron islands using variable temperature SP-STM. The thermal switching of individual islands was characterized at various temperatures by measuring the mean lifetime between two consecutive switching events. The characteristic parameters as the energy barrier and attempt frequency can be calculated by matching the results with the Néel-Brown law. The results are discussed with regard to the elongation of the islands along special crystallographic axes in order to clarify what kind of processes play a role in the magnetization reversal.

[1] R. Wiesendanger, Rev. Mod. Phys. 81, 1495 (2009).

[2] S. Krause et al., Phys. Rev. Lett. 103, 127202 (2009).