Electronic Raman scattering and photoluminescence from La${}_{0.7}$Sr${}_{0.3}$MnO${}_3$ exhibiting giant magnetoresistance

Abstract

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.

10 pages + 4 eps figures, Revtex 3.0, figures available on request