Crossover of Spin Correlations in the One-Dimensional Hubbard Model

The crossover of the spin correlation function from a non-half-filled to a half-filled band is investigated for the one-dimensional Hubbard model in the ground state. For the on-site interaction U→∞, it has the form at distance r, [formula omitted] where δ is the doping concentration away from half-filling. This form determines the crossover from the asymptotic behavior ∼ 1/r1.5 away from half-filling to ∼ 1/r at half-filling. At finite U, Monte Carlo results show that the peak of the equal-time spin structure factor S (Q) scales as S (Q)∝ - 1n δ leading to the same type of crossover. A unified description of the critical exponent of the antiferromagnetic spin correlation near half-filling in one- and two-dimensional Hubbard models is given.