Diagnostics of "colossal" magnetoresistance manganite films by Raman spectroscopy

Polarized Raman scattering by phonons is used to characterize thin films prepared by laser ablation of La1-xCaxMnO3 targets. It was found that, in the temperature range from 6 to 300 K, phonon spectra of La0.7Ca0.3MnO3 films exhibit observable differences from those in bulk materials (microcrystalline ceramics and single crystals). A significant difference was found in the spectra of "as-grown" films compared to those annealed in oxygen at 800°C. The observed Raman peaks and their linewidths exhibit an irregular temperature dependence near Tc. A correlation of Raman data with magnetization of the sample was also found. © 1998 American Institute of Physics.