Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 17: Correlated Electrons: Spin Systems, Itinerant Magnets 2
TT 17.3: Vortrag
Montag, 11. März 2013, 15:30–15:45, H19
Towards microscopic understanding of skyrmions in Cu2OSeO3: an effective theory description — Oleg Janson1, •Ioannis Rousochatzakis2, Alexander Tsirlin3, Ulrich Rössler2, Jeroen van den Brink2, and Helge Rosner1 — 1Max Planck Institute for Chemical Physics of Solids, Dresden, Germany — 2Leibniz Institute for Solid State and Materials Research, Dresden, Germany — 3National Institute of Chemical Physics and Biophysics, Tallinn, Estonia
We present a quantitative physical picture for the spin 1/2 ferrimagnetic helimagnet Cu2OSeO3 based on a DFT-based microscopic magnetic model. Besides clarifying the relevant low-energy magnetic degrees of freedom, the main successes of the theory are the following:
(i) it reveals an intimate connection between Cu2OSeO3 (an insulating ferrimagnet) and MnSi (a metallic ferromagnet);
(ii) it clarifies which Dzyaloshinskii-Moriya terms are responsible for the long-wavelength twisting, and gives a helix period of 58 nm, in very good agreement to the one (∼50 nm) reported by Lorentz transmission electron microscopy by Seki et al [1];
(iii) it predicts the presence of a small antiferromagnetic canting which is tied to the long-wavelength twisting;
(iv) it reveals the mechanism for the reduction of the Cu moments as observed by Bos et al [2].
[1] S. Seki, X. Z. Yu, S. Ishiwata, Y. Tokura, Science 336, 198 (2012)
J.-W. G. Bos, C. Colin, T. Palstra, Phys. Rev. B 78, 094416 (2008).