title: Magnon spectrum of the helimagnetic insulator Cu2OSeO3.
abstract: 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. Here we employ state-of-the-art inelastic neutron scattering 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 neutron spectroscopy 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.
authors.affiliation: Institut für Festkörperphysik, TU Dresden, Helmholtzstraße 10, D-01069 Dresden, Germany.
authors.forename: P Y
authors.initials: PY
authors.lastname: Portnichenko
authors.affiliation: Max Planck Institute for Solid State Research, Heisenbergstraße 1, D-70569 Stuttgart, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Romhányi
authors.affiliation: Institut für Festkörperphysik, TU Dresden, Helmholtzstraße 10, D-01069 Dresden, Germany.
authors.forename: Y A
authors.initials: YA
authors.lastname: Onykiienko
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, D-01187 Dresden, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Henschel
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, D-01187 Dresden, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schmidt
authors.affiliation: Institut für Festkörperphysik, TU Dresden, Helmholtzstraße 10, D-01069 Dresden, Germany.
authors.forename: A S
authors.initials: AS
authors.lastname: Cameron
authors.affiliation: Institut für Festkörperphysik, TU Dresden, Helmholtzstraße 10, D-01069 Dresden, Germany.
authors.forename: M A
authors.initials: MA
authors.lastname: Surmach
authors.affiliation: Institut für Festkörperphysik, TU Dresden, Helmholtzstraße 10, D-01069 Dresden, Germany.
authors.forename: J A
authors.initials: JA
authors.lastname: Lim
authors.affiliation: Heinz Maier-Leibnitz Zentrum (MLZ), TU München, Lichtenbergstraße 1, D-85747 Garching, Germany.
authors.forename: J T
authors.initials: JT
authors.lastname: Park
authors.affiliation: Jülich Centre for Neutron Science (JCNS), Forschungszentrum Jülich GmbH, Outstation at Heinz Maier-Leibnitz Zentrum (MLZ), Lichtenbergstraße 1, D-85747 Garching, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Schneidewind
authors.affiliation: Quantum Condensed Matter Division, Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee 37831, USA.
authors.forename: D L
authors.initials: DL
authors.lastname: Abernathy
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, D-01187 Dresden, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Rosner
authors.affiliation: Leibniz Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstraße 20, D-01069 Dresden, Germany.
authors.forename: Jeroen
authors.initials: J
authors.lastname: van den Brink
authors.affiliation: Institut für Festkörperphysik, TU Dresden, Helmholtzstraße 10, D-01069 Dresden, Germany.
authors.forename: D S
authors.initials: DS
authors.lastname: Inosov