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Spin wave and electromagnon dispersions in multiferroic MnWO4 as observed by neutron spectroscopy Isotropic Heisenberg exchange versus anisotropic Dzyaloshinskii Moriya interaction

By Y. Xiao, C.M.N. Kumar, S. Nandi, Y. Su, W.T. Jin, Z. Fu, E. Faulhaber, A. Schneidewind and Th Brückel

Abstract

High resolution inelastic neutron scattering reveals that the elementary magnetic excitations in multiferroic MnWO4 consist of low energy dispersive electromagnons in addition to the well known spin wave excitations. The latter can well be modeled by a Heisenberg Hamiltonian with magnetic exchange coupling extending to the 12th nearest neighbor. They exhibit a spin wave gap of 0.61 1 meV. Two electromagnon branches appear at lower energies of 0.07 1 and 0.45 1 meV at the zone center. They reflect the dynamic magnetoelectric coupling and persist in both the collinear magnetic and paraelectric AF1 phase and the spin spiral ferroelectric AF2 phase. These excitations are associated with the Dzyaloshinskii Moriya exchange interaction, which is significant due to the rather large spin orbit couplin

Topics: MnWO4, electromagnon, spin wave, dispersion
Publisher: 'American Physical Society (APS)'
Year: 2016
DOI identifier: 10.1103/PhysRevB.93.214428
OAI identifier: oai:helmholtz.HZB:89505
Provided by: HZB Repository

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