Spectra of dipole-active optical phonons in La0.7Ca0.3MnO3 epitaxial films

The reflectance of La_0.7Ca_0.3MnO₃ epitaxial films on perovskite substrates with a range of lattice constants is studied in the frequency range 50–5000 cm⁻¹. The results derived by modeling the spectra indicate that the internal optical phonon modes of the MnO₆ octahedra are strongly affected by the substrate-induced lattice distortion standing for the strong electron-phonon interaction in this system.