Parametrization of optical conductivity of the prototypic high-T-c cuprateLa2-xSrxCuO4

With the aim to propose a description as general as possible of 'non-metall ic' conducting materials, including the class of high-T-c cuprate supercond uctors, we test a model based on the generalization of the Lyddane-Sachs-Te ller relationship on the prototype of the class. This is also an extension of the conventional Drude model. It is shown to fit closely with the infrar ed-visible-near ultraviolet reflection spectra of La2-xSrxCuO4 for all x va rying from 0 to 0.34. Polaron formation is highly suggested for low x and t he model makes it possible to discriminate the trapped polarons from the mo bile species. The two- to three-dimensional change of regime is accompanied by a diffusive non-Drude to conventional pseudo-Drude behavior of the mobi le charge carriers. (C) 2001 Elsevier Science B.V. All rights reserved.