Electronic Raman scattering and photoluminescence from   La$_{0.7}$Sr$_{0.3}$MnO$_3$ exhibiting giant magnetoresistance
  Raman and Photoluminescence (PL) experiments on correlated metallic La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ have been carried out using different excitation wavelengths as a function of temperature from 15 K to 300 K. Our data suggest a Raman mode centered at 1800 cm$^{-1}$ and a PL band at 2.2 eV. The intensities of the two peaks decrease with increasing temperature. The Raman mode can be attributed to a plasmon excitation whose frequency and linewidths are consistent with the measured resistivities. The PL involves intersite electronic transitions of the manganese ions. 
Rajeev Gupta, A.K. Sood, R. Mahesh and C.N.R. Rao