INCOMMENSURATE SPIN FLUCTUATIONS IN THE 2-DIMENSIONAL T-T'-U MODEL

Magnetic properties of the two-dimensional t-t'-U model are investigat ed by studying the static spin magnetic susceptibility as a function o f momentum for various temperatures. The calculations are performed by means of the composite operator method in the static approximation. B y increasing the value of the t' parameter, the magnetic scattering in the reciprocal space evolves to an isotropic structure. It is shown t hat the results are in qualitative agreement with the experimental sit uation observed in LSCO and YBCO compounds. (C) 1998 Elsevier Science B.V.