Susceptibility and Effective Interaction in the Dilute Two Dimensional Hubbard Model

Abstract

(1) The wave number dependence of the static spin susceptibility χ(q) and (2) the effective interaction between quasiparticlesmediated by spin fluctuations in the dilute two dimensional Hubbard modelare investigated.The quantum Monte Carlo method (QMC) and the fluctuation exchange approximation (FLEX)are applied to this model.It is found that a maximum at wave number q=0 emerges and develops in χ(q) as the interaction U gets strong.It is also found that the most attractive component of the effective interaction mediated by spin fluctuationsis the p-wave component in the strong coupling region where a maximum at q=0 devolops in χ(q).