Jahn-Teller dynamics in charge-ordered manganites from Raman spectroscopy

The Raman spectra of the charge-ordered manganite Pr0.65Ca0.35MnO3 were stu died as functions of temperature and excitation energy and compared to magn etic moment and electrical conductivity behaviors. Both the charge ordering (T-co approximate to 225 K) and the antiferromagnetic transitions (T-N app roximate to 175 K) affect the spectral shape and intensity, indicating stro ng charge-lattice and spin-lattice couplings. Below T-co a transition from dynamic Jahn-Teller distortions to a collective static distortion takes pla ce. A change of the spectra is observed on increasing the excitation energy above 2.5 eV and it is attributed to a resonant polaron excitation.