Terahertz spectroscopy of electromagnons inEu1−xYxMnO3

Dielectric permittivity spectra of yttrium-doped $\mathrm{Eu}\mathrm{Mn}{\mathrm{O}}_3$ in the composition range $0⩽x⩽0.5$ have been investigated in the terahertz frequency range. Magnetoelectric contributions to the permittivity were observed in all compositions for ac electric fields parallel to the crystallographic $a$ axis. Well-defined electromagnons exist for $x⩾0.2$ close to $\nu \sim 20{\mathrm{cm}}^{-1}$ and with dielectric strength strongly increasing on doping. In addition to electromagnons, a broad contribution of magnetoelectric origin is observed for all compositions. For ${\mathrm{Eu}}_{0.8}{\mathrm{Y}}_{0.2}\mathrm{Mn}{\mathrm{O}}_3$, the electromagnons can be suppressed by external magnetic fields which induce a canted antiferromagnetic phase. Magnetoelectric effects in the different doping regimes are discussed in detail.