RAMAN LINE-SHAPES FROM SPUTTERED THIN-FILMS OF Y(PR)BA2CU3O6- FINE-STRUCTURES AND OXYGEN ORDERING(DELTA )

A temperature dependence study of Raman line shapes taken from superco nducting and insulating Y(Pr)Ba2Cu3O6+delta thin films with well-chara cterized electrophysical properties and morphologies (a-axis or c-axis orientation) has been carried out using the excitation energies at 1. 83 eV and 2.41 eV. Ba and Cu bands show doublers, with 113-119 cm(-1) and 146-152 cm(-1) components and have been calculated using a Green's function model. The shapes of the 113 and 152 cm(-1) lines are well d escribed by Lorentzians whereas those of the other two components can be satisfactorily reproduced in the assumption that two phonons of bar e frequencies 119 and 146 cm(-1) interact with a common continuum of e xcitations. The temperature dependence of the phonon-continuum couplin g parameters allows us to ascribe the scattering continuum to low-ener gy electronic interband transitions. The model is able to explain qual itatively the overestimated mixing between pure Ba and plane Cu A(g) v ibrational modes found in previous first-principles calculations. We a lso find that for the 1.83 eV exciting line, the B-1g oxygen phonon at 335 cm(-1) presents a strong Fano effect and anomalous temperature de pendence. We link Raman features occuring at approximate to 220-240, 2 70-290, and 560-596 cm(-1) to the existence of local variations in oxy gen composition resulting from the conditions of deposition. These lin es could originate from chain defects and be activated by a coupling b etween A(g) and B-2g-B-3g modes. The presence of microphases of oxygen -depleted domains (ortho-II phase) reproducing macroscopic oxygen diso rder is proposed.