Lattice and charge excitations in La1-xSrxMnO3

We employ inelastic Light scattering to study the dependence of the lattice and charge excitations in La1-xSrxMnO3 compounds on doping and temperature. The phonons reveal strong local lattice distortions in the paramagnetic state, which gradually vanish below the ferromagnetic transition. We identify charge excitations in the metallic state. They exhibit a dependence on the doping level and symmetry selection rules typical for a plasmonlike excitation. Their energy scale of 100 meV requires a low-carrier-density component of the plasma outlining the importance of electronic interactions in La1-xSrxMnO3.