ELECTRONIC RAMAN-SCATTERING IN FILLING-CONTROLLED METALS - SR1-XLAXTIO3

Electronic Raman scattering has been investigated for metallic Sr1-xLaxTiO3 in which the 3d band filling (x) can be systematically changed from x = 0 (a band insulator) to x = 1 (a Mott-Hubbard insulator). The symmetry dependence of the scattering intensity can be accounted for in terms of the neutral carrier density fluctuation model. However, a systematic change of the spectral shape with the carrier density (congruent-to x) is observed. All the spectra can be reproduced by a relaxational function with an omega-dependent scattering rate (GAMMA). The omega dependence of GAMMA gets stronger with x, which is in accord with the x-dependent enhancement of the effective mass, due to the electron correlation effect.