Jahn-teller dynamics in charge-ordered manganites from raman spectroscopy
The Raman spectra of the charge-ordered manganite Pr0.65Ca0.35MnO3 were studied as functions of temperature and excitation energy and compared to magnetic moment and electrical conductivity behaviors. Both the charge ordering ( T(co) approximately 225 K) and the antiferromagnetic transitions ( T(N) approximately 175 K) affect the spectral shape and intensity, indicating strong charge-lattice and spin-lattice couplings. Below T(co) a transition from dynamic Jahn-Teller distortions to a collective static distortion takes place. 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.
Dediu
V
Istituto di Spettroscopia Molecolare, CNR, via Gobetti 101, 40129 Bologna, Italy.
Ferdeghini
C
Matacotta
FC
Nozar
P
Ruani
G