Studies on Phonon spectra of high Temperature Superconductors

The role of superconductivity can be understood by the assignments of spectral features to lattice vibrations. Raman and infrared studies have contributed significantly to the explication of high Tc mechanics. In the present work, normal coordinate calculations have been carried out to study the vibrational analysis of perovskite like antiferromagnetic compound YBaCuFeO5. It is important to have knowledge of phonon frequency spectrum for the interpretation of physical properties such as thermal, elastic, infrared, etc., which can be achieved by means of theoretical models of lattice dynamics. A three-body force shell model (TBSM) which takes into account many body interactions is applied to study the lattice dynamics of high Tc infrared and Raman spectrum, the phonon frequencies at the centre of Brillouin zone are presented and vibrational assignments are discussed. The calculations yield not only the phonon frequencies at the centre, but also throughout the Brillouin zone.