Quasiparticle approach to electronic Raman scattering in overdoped cuprates

High-Tc superconductors can be described as normal, though strongly correlated, metals in the overdoped regime. This implies that the conduction electrons in these materials can be viewed as independent quasiparticles with defined momenta and a certain lifetime. Here we explore the capability of this concept to explain the electronic Raman response in overdoped cuprates. The Raman response can be calculated in linear response theory using a generalized Kubo formula. Owing to the k-dependence of the Raman vertices, selected by the polarizations of the incoming and outgoing photons, different parts of the Brillouin zone can be projected out independently. In order to evaluate the Kubo formula one additionally needs the spectral function of the quasiparticles. In our model we assume a bandstructure and quasiparticle lifetimes as derived from ARPES experiments in order to calculate the Raman response for the B1g and B2g symmetries. Comparing model data and Raman spectra of La2-xSrxCO4 and Bi2Sr2CaCu2O8+δ, we find remarkable agreement concerning symmetry and temperature dependences in both material systems. This suggests that the quasiparticle approach is a reasonable starting point to explain carrier dynamics in overdoped cuprates. (orig.)