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We present a rationalization of the Raman spectra of orthorhombic andrhombohedral, stoichiometric and doped, manganese perovskites. In particular westudy RMnO3 (R= La, Pr, Nd, Tb, Ho, Er, Y and Ca) and the different phases ofCa or Sr doped RMnO3 compounds as well as cation deficient RMnO3. The spectraof manganites can be understood as combinations of two kinds of spectracorresponding to two structural configurations of MnO6 octahedra andindependently of the average structure obtained by diffraction techniques. Themain peaks of compounds with regular MnO6 octahedra, as CaMnO3, highly Ca dopedLaMnO3 or the metallic phases of Ca or Sr doped LaMnO3, are bending and tiltMnO6 octahedra modes which correlate to R-O(1) bonds and Mn-O-Mn anglesrespectively. In low and optimally doped manganites, the intensity and width ofthe broad bands are related to the amplitude of the dynamic fluctuationsproduced by polaron hopping in the paramagnetic insulating regime. Theactivation energy, which is proportional to the polaron binding energy, is themeasure of this amplitude. This study permits to detect and confirm thecoexistence, in several compounds, of a paramagnetic matrix with latticepolaron together with regions without dynamic or static octahedron distortions,identical to the ferromagnetic metallic phase. We show that Raman spectroscopyis an excellent tool to obtain information on the local structure of thedifferent micro or macro-phases present simultaneously in many manganites.Comment: Submitted to PR

Raman phonons as a probe of disorder, fluctuations, and local structure in doped and undoped orthorhombic and rhombohedral manganites