THEORETICAL-STUDY OF RAMAN-SPECTRA OF CUPRATE SYSTEMS IN NORMAL-STATE

Here we present a microscopic theory to explain different Raman phonon modes of the cuprates in normal state. We used the electronic Hamilto nian of Fulde in presence of anti-ferromagnetism. We added phonon inte raction to the hybridisation between the conduction electrons of the s ystem and the f-electrons. The spectral density is calculated by the G reen function technique of Zubarev at zero wave vector and low tempera ture limit. The spectral density is studied in detail by varying model parameters like position of f-level (epsilon(f)), the effective elect ron-phonon coupling strength (g), the staggered magnetic field (h) and the hybridisation parameter (V). Four Raman active modes are observed in addition to the original phonon peak. Then their softening and har dening behaviour and change in peak height are studied, These paramete rs influence the Raman modes substantially. (C) 1998 Elsevier Science Ltd. All rights reserved.