Polarized Inelastic Neutron Scattering study of TbMnO$_3$*

Low energy collective excitations in TbMnO$_3$ were examined using polarized inelastic neutron scattering. By probing spin flip and non-spin-flip excitations with a guide field along wave vector transfer, Q, we separated the magnetic and vibrational components of excitations at high symmetry points in the Brillouin zone. We report signatures of coupled magnon-phonon excitations in the ferroelectric-spiral state, which disappear in the paramagnetic phase. These results will be discussed in terms of current models of electromagnons in the \textit{R}MnO$_3$ multiferroic family.