Monte Carlo study of the pairing interaction in the two-leg Hubbard ladder

Monte Carlo calculations of the irreducible particle-particle interaction on a two-leg Hubbard ladder doped near half-filling are reported. As the temperature is lowered, this interaction develops structure in momentum space similar to the magnetic susceptibility chi(q) and reflects the development of strong short-range antiferromagnetic correlations. Using this interaction, the eigenfunction of the leading singlet pair eigenvalue is found to have d(x2-y2)-like symmetry. The single-particle spectral weight is also shown to peak near (pi,0) and (0,pi) when the ratio of the inter- to intra-chain hopping t(perpendicular to)/t approximate to 1.5, leading to an increased tendency for pairing. (C) 1997 Elsevier Science B.V.