Coupling between phonons and magnetic excitations in orthorhombic Eu1-xYxMnO3

In this work we present a detailed study of the structural and lattice-dynamic properties of Y-doped ${\text{EuMnO}}_{3}$ ceramics (${\text{Eu}}_{1\ensuremath{-}x}{\text{Y}}_{x}{\text{MnO}}_{3}$ with $0\ensuremath{\le}x\ensuremath{\le}0.5$). A thorough analysis toward the correlation between both structural and Raman modes parameters has been undertaken. Our results provide evidence for two main structural distortions of ${\text{MnO}}_{6}$ octahedra, arising from a cooperative Jahn-Teller and rotational distortions in these compounds. The temperature dependence of the ${\text{B}}_{1\text{g}}$ symmetric stretching mode of the ${\text{MnO}}_{6}$ units has revealed either a positive or negative shift regarding the pure anharmonic temperature dependence of the phonon frequency, which strongly depends on the Y concentration. This frequency renormalization is explained in terms of a competition between ferromagnetic and antiferromagnetic interactions. Frequency shifts observed well above the N\'eel temperature are likely associated with the coupling between phonons and electromagnons, which provides further grounds for the existence of strong spin-phonon coupling in this compound. Both polar and magnetoelectric properties ascertained for $x=0.2$ provide clear evidence of the central role played by spin-phonon coupling in yielding the physical behavior of the Y-doped ${\text{EuMnO}}_{3}$ system.