Momentum dependence of the spin and charge excitations in the two dimensional Hubbard model

TL;DR

This paper investigates how spin and charge excitations in the 2D Hubbard model depend on momentum, revealing behaviors consistent with high-temperature superconductor observations, especially near half filling.

Contribution

It provides a detailed analysis of the momentum dependence of spin and charge excitations in the 2D Hubbard model using RPA spectra derived from inhomogeneous mean field textures.

Findings

Spin excitations show a commensurate peak at half filling and incommensurate peaks near half filling.

Charge excitations are localized near (0,0) at half filling and fill the entire Brillouin Zone at higher doping.

Results align with experimental features of high-Tc superconductors.

Abstract

The low energy spin and charge excitations in the 2D Hubbard model near half filling are analyzed. The RPA spectra derived from inhomoheneous mean field textures are analyzed. Spin excitations show a commensurate peak at half filling, incommensurate peaks near half filling, and a broad background typical of a dilute Fermi liquid away from half filling. Charge excitations, near half filling, are localized near (0,0), and they occupy a small portion of the Brillouin Zone, in a way consistent with the existence of a small density of carriers, and a small Fermi surface. At higher hole densities, they fill the entire BZ, and can be understood in terms of a conventional Fermi liquid picture. The results are consistent with the observed features of the high-T$_c$ superconductors.