Charge and spin excitations of insulating lamellar copper oxides

TL;DR

This paper models the low-energy charge and spin responses of insulating Sr_2CuO_2Cl_2 using an extended Hubbard model, combining various computational methods to match experimental observations.

Contribution

It introduces a comprehensive one-band Hubbard model including up to third-nearest neighbor hoppings, analyzed through multiple computational techniques, to explain experimental data on insulating copper oxides.

Findings

Long-range hopping flattens the quasiparticle band around (0,π).

Calculated Raman profiles show features due to 2- and 4-magnon scattering.

Model successfully reproduces experimental charge and spin responses.

Abstract

A consistent description of low-energy charge and spin responses of the insulating Sr_2CuO_2Cl_2 lamellar system is found in the framework of a one-band Hubbard model which besides $U$ includes hoppings up to 3^{rd} nearest-neighbors. By combining mean-field calculations, exact diagonalization (ED) results, and Quantum Monte Carlo simulations (QMC), we analyze both charge and spin degrees of freedom responses as observed by optical conductivity, ARPES, Raman and inelastic neutron scattering experiments. Within this effective model, long-range hopping processes flatten the quasiparticle band around $(0,\pi)$. We calculate also the non-resonant A_{1g} and B_{1g} Raman profiles and show that the latter is composed by two main features, which are attributed to 2- and 4-magnon scattering.