Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 34: Correlated Electrons: Frustrated Magnets - Chiral Magnets & RuCl₃

TT 34.4: Vortrag

Dienstag, 8. März 2016, 14:45–15:00, H20

Magnon spectrum of the helimagnetic insulator Cu₂OSeO₃ — P. Y. Portnichenko¹, J. Romhányi², Y. A. Onykiienko¹, A. Henschel³, M. Schmidt³, A. S. Cameron¹, M. A. Surmach¹, J. A. Lim¹, J. T. Park⁴, A. Schneidewind⁵, D. L. Abernathy⁶, H. Rosner³, J. van den Brink⁷, and •D. S. Inosov¹ — ¹TU Dresden — ²MPI-FKF, Stuttgart — ³MPI-CPfS, Dresden — ⁴MLZ, Garching — ⁵JCNS, Jülich — ⁶ORNL, Oak Ridge — ⁷IFW Dresden

Complex low-temperature ordered states in chiral magnets are typically governed by a competition between multiple magnetic interactions. The chiral-lattice multiferroic Cu₂OSeO₃ became the first insulating helimagnetic material in which a long-range order of topologically stable spin vortices known as skyrmions was established. We employed state-of-the-art inelastic neutron scattering (INS) to comprehend the full three-dimensional spin excitation spectrum of Cu₂OSeO₃ over a broad range of energies. Distinct types of high- and low-energy dispersive magnon modes separated by an extensive energy gap are observed in excellent agreement with the previously suggested microscopic theory based on a model of entangled Cu₄ tetrahedra. The comparison of our INS data with model spin-dynamical calculations based on these theoretical proposals enables an accurate quantitative verification of the fundamental magnetic interactions in Cu₂OSeO₃ that are essential for understanding its abundant low-temperature magnetically ordered phases.