Regensburg 2013 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 17: Correlated Electrons: Spin Systems, Itinerant Magnets 2

TT 17.4: Talk

Monday, March 11, 2013, 15:45–16:00, H19

Towards microscopic understanding of skyrmions in Cu₂OSeO₃: a DFT study — •Oleg Janson¹, Ioannis Rousochatzakis², Alexander Tsirlin^1,3, 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

Unlike most undoped cuprates, the S=1/2 Heisenberg magnet Cu₂OSeO₃ exhibits a ferrimagnetic ground state and a sizable magnetoelectric coupling. Furthermore, recent experimental studies reported magnetic-field-induced emergence of skyrmions in this insulating material. Based on extensive DFT band structure calculations, we evaluate the microscopic magnetic model, including isotropic (Heisenberg) and anisotropic (Dzyaloshinskii-Moriya) terms. We extract five relevant magnetic couplings that form a complex, but non-frustrated spin model which can be described as a pyrochlore lattice of magnetic tetrahedra. The model parameters are justified by quantum Monte-Carlo simulations and subsequent comparison to the experiments.