Spin-phonon coupling in multiferroic YbMnO(3) studied by Raman scattering.

Hexagonal YbMnO(3) bulk polycrystals were prepared and studied by Raman scattering in the temperature range of 15-300 K. A total of 15 phonon modes of A(1), E(1) and E(2) type were identified. Some E(2) phonon modes showed anomalous temperature variations in frequency at T(N)∼80 K, suggesting a coupling between the spin and phonon systems below T(N). As another evidence of spin-phonon coupling, softening of an A(1)-phonon mode for the O-Mn vibration was observed at ∼T(N). Substitution of Mn by Al suggests this view.