Magnetic Excitations in the Low-Temperature Ferroelectric Phase of Multiferroic YMn2O5 Using Inelastic Neutron Scattering

We studied magnetic excitations in a low-temperature ferroelectric phase of the multiferroic YMn2O5 using inelastic neutron scattering (INS). We identify low-energy magnon modes and establish a correspondence between the magnon peaks observed by INS and electromagnon peaks observed in optical absorption [A. B. Sushkov et al., Phys. Rev. Lett. 98, 027202 (2007).]. Furthermore, we explain the microscopic mechanism, which results in the lowest-energy electromagnon peak, by comparing the inelastic neutron spectral weight with the polarization in the commensurate ferroelectric phase.