A unified theory of spin and charge excitations in high-$T_c$ cuprates: Quantitative comparison with experiment and interpretation

Abstract

We provide a unified interpretation of both paramagnon and plasmon modes in high-Tc copperoxides, and verify it quantitatively against available resonant inelastic x-ray scattering (RIXS) data across the hole-doped phase diagram. Three-dimensional extended Hubbard model, with included long-range Coulomb interactions and doping-independent microscopic parameters for both classes of quantum fluctuations, is used. Collective modes are studied using VWF+1/N f approach which extends variational wave function (VWF) scheme by means of an expansion in inverse number of fermionic flavors (1/N f ). We show that intense paramagnons persist along the anti-nodal line from the underdoped to overdoped regime and undergo rapid overdamping in the nodal direction. Plasmons exhibit a three-dimensional character, with minimal energy corresponding to anti-phase oscillations on neighboring CuO2 planes. The theoretical spin-and charge excitation energies reproduce semi-quantitatively RIXS data for (Bi, Pb)2(Sr, La)2CuO 6+δ . The present VWF+1/N f analysis of dynamics and former VWF results for static quantities combine into a consistent description of the principal properties of hole-doped high-Tc cuprates as strongly correlated systems.