Charge and spin excitations of insulating lamellar copper oxides

Abstract

A consistent description of low-energy charge and spin responses of the insulating ${\mathrm{Sr}}_{2}$${\mathrm{CuO}}_{2}$${\mathrm{Cl}}_{2}$ lamellar system is found in the framework of a one-band Hubbard model which besides U includes hoppings up to third nearest neighbors. By combining mean-field calculations, exact diagonalization results, and quantum Monte Carlo simulations, we analyze both charge and spin degrees of freedom responses as observed by optical conductivity, angular-resolved photoemission spectroscopy Raman and inelastic neutron-scattering experiments. Within this effective model, long-range hopping processes flatten the quasiparticle band around (0,\ensuremath{\pi}). We calculate also the nonresonant ${\mathrm{A}}_{1\mathrm{g}}$ and ${\mathrm{B}}_{1\mathrm{g}}$ Raman profiles and show that the latter is composed by two main features, which are attributed to two- and four-magnon scattering.