title: Temperature-dependent interplay of Dzyaloshinskii-Moriya interaction and single-ion anisotropy in multiferroic BiFeO3.
abstract: Low-energy magnon excitations in multiferroic BiFeO3 were measured in detail as a function of temperature around several Brillouin zone centers by inelastic neutron scattering experiments on single crystals. Unique features around 1 meV are directly associated with the interplay of the Dzyaloshinskii-Moriya interaction and a small single-ion anisotropy. The temperature dependence of these and the exchange interactions were determined by fitting the measured magnon dispersion with spin-wave calculations. The spectra best fit an easy-axis type magnetic anisotropy and the deduced exchange and anisotropy parameters enable us to determine the anharmonicity of the magnetic cycloid. We then draw a direct connection between the changes in the parameters of spin Hamiltonian with temperature and the physical properties and structural deformations of BiFeO3.
authors.affiliation: Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-747, Korea and Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea.
authors.forename: Jaehong
authors.initials: J
authors.lastname: Jeong
authors.affiliation: Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-747, Korea and Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea.
authors.forename: Manh Duc
authors.initials: MD
authors.lastname: Le
authors.affiliation: Laboratoire Léon Brillouin, CEA-CNRS, CEA-Saclay, F-91191 Gif-sur-Yvette, France.
authors.forename: P
authors.initials: P
authors.lastname: Bourges
authors.affiliation: Laboratoire Léon Brillouin, CEA-CNRS, CEA-Saclay, F-91191 Gif-sur-Yvette, France.
authors.forename: S
authors.initials: S
authors.lastname: Petit
authors.affiliation: Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Furukawa
authors.affiliation: Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon 305-353, Korea.
authors.forename: Shin-Ae
authors.initials: SA
authors.lastname: Kim
authors.affiliation: Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon 305-353, Korea.
authors.forename: Seongsu
authors.initials: S
authors.lastname: Lee
authors.affiliation: Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.
authors.forename: S-W
authors.initials: SW
authors.lastname: Cheong
authors.affiliation: Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-747, Korea and Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea.
authors.forename: Je-Geun
authors.initials: JG
authors.lastname: Park