Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 21: Invited Talk Stefan Blügel

O 21.1: Invited Talk

Tuesday, February 26, 2008, 09:30–10:15, HE 101

Electrons at Surfaces Taking an Unexpected Turn — •Stefan Blügel — Institut für Festkörperforschung, Forschungszentrum Jülich, D-52425 Jülich, Germany

Electrons in the vicinity of surfaces are in a space asymmetric environment. This causes a number of interesting phenomena, like the Rashba spin-orbit effect [1], spin-depending scattering [2] and spin-polarized electrons [3] at non-magnetic surfaces, which little attention had been paid to in the past. For electrons at magnetic surfaces, thin films and nanostructures also time-inversion symmetry is broken. This can give rise to an unidirectional exchange interaction, known as Dzyaloshinsky-Moriya (DM) interaction. Although this interaction, favoring spatially rotating spin structures, is known for nearly 50 years, its consequences for the magnetic structure in low-dimensional magnets remained basically unexplored. We show by ab initio calculations that the DM interaction can cause homochiral magnetic phases at achiral surfaces – phases, which had been overlooked during the past 20 years – but have been observed recently in terms of a left rotating cycloidal spiral for Mn on W(110) [4]. Theoretical models [5] display a rich phase diagram of possible magnetic phases. At the end, I will present arguments motivating the search for the existence of a lattice of nano-skyrmions.

[1] Yu. M. Koroteev et al., Phys. Rev. Lett. 93, 046403 (2004).

[2] J.I. Pascual et al., Phys. Rev. Lett. 93, 196802 (2004).

[3] T. Hirahara et al., Phys. Rev. Lett. 97, 146803 (2006).

[4] M. Bode et al., Nature 447, 190 (2007).

[5] M. Heide et al., submitted to Phys. Rev. B.