title: Electromagnon dispersion probed by inelastic X-ray scattering in LiCrO2.
abstract: Inelastic X-ray scattering with meV energy resolution (IXS) is an ideal tool to measure collective excitations in solids and liquids. In non-resonant scattering condition, the cross-section is strongly dominated by lattice vibrations (phonons). However, it is possible to probe additional degrees of freedom such as magnetic fluctuations that are strongly coupled to the phonons. The IXS spectrum of the coupled system contains not only the phonon dispersion but also the so far undetected magnetic correlation function. Here we report the observation of strong magnon-phonon coupling in LiCrO2that enables the measurement of magnetic correlations throughout the Brillouin zone via IXS. We find electromagnon excitations and electric dipole active two-magnon excitations in the magnetically ordered phase and heavily damped electromagnons in the paramagnetic phase of LiCrO2. We predict that several (frustrated) magnets with dominant direct exchange and non-collinear magnetism show surprisingly large IXS cross-section for magnons and multi-magnon processes.
authors.affiliation: Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, 5232 Villigen, Switzerland.|Laboratory for Quantum Magnetism, Institute of Physics, EPFL, 1015 Lausanne, Switzerland.
authors.forename: Sándor
authors.initials: S
authors.lastname: Tóth
authors.affiliation: Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, 5232 Villigen, Switzerland.|Department of Quantum Matter Physics, University of Geneva, 1211 Genève, Switzerland.
authors.forename: Björn
authors.initials: B
authors.lastname: Wehinger
authors.affiliation: Laboratory for Scientific Developments and Novel Materials, Paul Scherrer Institute, 5232 Villigen, Switzerland.
authors.forename: Katharina
authors.initials: K
authors.lastname: Rolfs
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.|Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.
authors.forename: Turan
authors.initials: T
authors.lastname: Birol
authors.affiliation: Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, 5232 Villigen, Switzerland.
authors.forename: Uwe
authors.initials: U
authors.lastname: Stuhr
authors.affiliation: Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan.|Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takatsu
authors.affiliation: Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Kimura
authors.affiliation: Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Kimura
authors.affiliation: Laboratory for Quantum Magnetism, Institute of Physics, EPFL, 1015 Lausanne, Switzerland.
authors.forename: Henrik M
authors.initials: HM
authors.lastname: Rønnow
authors.affiliation: Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, 5232 Villigen, Switzerland.|Department of Quantum Matter Physics, University of Geneva, 1211 Genève, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Rüegg