Regensburg 2013 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 44: Surface Magnetism (jointly with O)

MA 44.11: Vortrag

Donnerstag, 14. März 2013, 18:00–18:15, H3

Complex Magnetism in Fe nanoclusters on Ir(111) — •David Bauer, Phivos Mavropoulos, Rudolf Zeller, and Stefan Blügel — Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, D-52425 Jülich

Recently, a square lattice of skyrmions of nanoscale dimension has been experimentally identified by spin-polarized scanning tunneling microscopy combined with first-principles calculations [1] as the magnetic ground state of an hexagonal Fe monolayer on the Ir(111) substrate. The magnetic structure is a result of a fine balance between the Heisenberg and biquadratic exchange, the four-spin interaction, magnetic anisotropy and the Dzyaloshinskii-Moriya interaction. This raises the question whether a single skyrmion is already encoded in a minimal hexagonal cluster of 7 atoms or e.g. in the next larger one of 19 atoms. To shed light onto this problem we apply our recently developed all-electron full-potential relativistic Korringa-Kohn-Rostoker Green-function method jointly with a model spin-dynamics code to study the non-collinear magnetism in finite nano-structures and clusters perfectly embedded in bulk materials or on surfaces.We find that the finite size of these clusters changes the balance between the magnetic interactions significa ntly. For example, also for the 19 atom cluster a strong non-collinear formation of spins was found, but qualitatively different to the skyrmion in the sense that most spins relax to an almost rectangular alignment with respect to their neighbors indicating that the Dzyaloshinskii-Moriya interaction determines the magnetic structure.

[1] S. Heinze et al. Nature Phys. 7, 713 (2011).