Electron–spin-fluctuation interaction in the 2D one-band Hubbard model

Abstract

We study numerically the renormalization of the electron–spin-fluctuation (el–sp) interaction or vertex in the two-dimensional one-band Hubbard model with spin-fluctuation momentum transfer q = (π, π). Our simulations are based on a new numerically exact technique to extract the vertex, which is especially important for the physically relevant case, i.e., strong correlations, which cannot be controlled perturbatively. We find that the el–sp vertex decreases quite generally with decreasing temperature at all doping densities. As a combination of two concurring effects, i.e., the decrease of the vertex and the increase of the spin susceptibility, the effective pairing interaction flattens off with lowering temperature. Our findings imply that in the high- T c cuprates the pairing mediated by antiferromagnetic spin fluctuations is substantially reduced due to vertex corrections.