Mp. Lopezsancho et al., MOMENTUM DEPENDENCE OF THE SPIN AND CHARGE EXCITATIONS IN THE 2-DIMENSIONAL HUBBARD-MODEL, Zeitschrift fur Physik. B, Condensed matter, 101(2), 1996, pp. 283-288
The low energy spin and charge excitations in the 2D Hubbard model nea
r half filling are analyzed. The RPA spectra derived from inhomoheneou
s mean field textures are analyzed. Spin excitations show a commensura
te peak at half filling, incommensurate peaks near half filling, and a
broad background typical of a dilute Fermi liquid away from half fill
ing. Charge excitations, near half filling, are localized near (0,0),
and they occupy a small portion of the Brillouin Zone, in a way consis
tent with the existence of a small density of carriers, and a small Fe
rmi surface. At higher hole densities, they fill the entire BZ, and ca
n be understood in terms of a conventional Fermi liquid picture. The r
esults are consistent with the observed features of the high-T-c super
conductors.