Reentrant electromagnons in multiferroic Eu$_{0.75}$Y$_{0.25}$MnO$_3$ in the H-T phase diagram

The electromagnon spectra of Eu$_{0.75}$Y$_{0.25}$MnO$_3$ has been measured as a function of magnetic field $H\| c$ up to 8 T and temperature between 5 and 300 K. Three magnetic induced electric dipole features reported earlier\footnote{Valdes Aguilar, et al. PRB \textbf{76}, 060404(R) (2007)} are observed to weaken simultaneously but not shift for increasing field. These electromagnon features all show reentrant behavior as a function of temperature for $H >$ 6 T, and track with the anomalies in the static dielectric constant, confirming their electromagnon origin. While the magnetic structure of Eu$_{0.75}$Y$_{0.25}$MnO$_3$ is unknown, it is assumed that it is a cycloidal magnet where the spins lie in the crystallographic \textit{a-b} plane, based on the behavior of the magnetic susceptibility and the direction of static polarization \textbf{P}. Therefore, it appears that the electromagnon selection rule, $e\|$\textit{a}, in all the multiferroic $R$MnO$_3$ manganites is independent of the spin plane and polarization direction. We will compare the phase diagrams of Eu$_{0.75}$Y$_{0.25}$MnO$_3$ and TbMnO$_3$ where similar anomalies are observed.