Hybrid Goldstone modes in multiferroics

By using polarized inelastic neutron scattering measurements, we show that the spin-lattice quantum entanglement in mutliferroics results in hybrid elementary excitations, involving spin and lattice degrees of freedom. These excitations can be considered as multiferroic Godstone modes. We argue that the Dzyaloshinskii-Moriya interaction could be at the origin of this hybridization.