  In this work we present a detailed study of the structural and lattice
dynamic properties of Y-doped EuMnO3 ceramics (Eu1-xYxMnO3, with 0<x<0.55). A
thorough analysis towards the correlation between both structural and Raman
modes parameters has been undertaken. Our results provide evidence for two main
structural distortions of MnO6 octahedra, arising from a cooperative
Jahn-Teller and rotational distortions in these compounds. The temperature
dependence of the B1g symmetric stretching mode of the MnO6 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 ferro and antiferromagnetic interactions. The pronounced
frequency renormalization of the symmetric stretching mode for x=0.2 evidences
the predominance of the ferromagnetic interactions against the
antiferromagnetic ones, which is in good correlation with the spontaneous
magnetization measured in this compound. The emerging of the shifts referred
well above the Neel temperature is likely associated with the coupling between
phonons and dynamical fluctuations of the magnetic system, which provides
further grounds for the existence of strong spin-phonon coupling in this
compound.
