Evolution of the optical properties of single-crystal La1-xSrxMnO3

An ellipsometric method is used to study the dispersion of the real epsilon(1)(omega) and imaginary epsilon(2)(omega) parts of the complex dielectric permittivity of single-crystal La1-xSrxMnO3 (x = 0.1, 0.2, and 0.3) for energies from 100 meV to 5 eV at room temperature. It is found that, when lanthanum is replaced by strontium, the optical spectrum changes fundamentally. A shift in the main features of the spectrum of initial LaMnO3 at 1.9 and 4.7 eV to lower energies takes place, as well as a partial redistribution of the optical-conductivity spectral weight in the band gap region E < 1.7 eV. For compositions with x = 0.2 and 0.3, a fine structure of the interband absorption is observed against a background of non-Drude optical conductivity at low energies. (C) 1999 American Institute of Physics. [S1063-7834(99)01908-5].