A model study of CDW and SDW mixed mode exciton peak in Raman scattering of high-Tc superconductors

Abstract

We present the results of a model study of Raman scattering of the spin density wave (SDW) and charge density wave (CDW) ordered high-Tc systems in normal state. The system is described by the interplay of the SDW and CDW orders in under-doped region. Though the SDW state is not normally coupled to the lattice, we calculate the phonon response of the system with a view to examine the possibility of observing the SDWmode due to the presence of CDW interaction. The CDW and SDW order parameters are calculated by Zubarev's Green's function technique and are solved self-consistently. The Raman scattering intensity is calculated from the imaginary part of the phonon Green's function assigning a arbitrary spectral width. The spectral density function display two mixed modes of excitation peaks at energies 2(ΔCDW + ΔSDW) and 2(ΔCDW − ΔSDW) besides a phonon momentum transfer energy excitation peak at very low energies.