Enhanced d -wave pairing in the two-dimensional Hubbard model with periodically modulated hopping amplitudes.

Utilizing determinant quantum Monte Carlo algorithm, the evolution of the-wave pairing in the Hubbard model on the square lattice tuned by the periodically modulated hopping amplitudes is studied. The hopping amplitudes are homogeneous in thexˆ-direction, while in theyˆ-direction the hopping amplitudes are modulated with period, wherety=t+dt,ty'=t-(P-1)dt, and the modulation periodequals 2, 3 and 4 lattice spacings. The latter two modulation periods are motivated by the observation of period-3 and period-4 stripe order in cuprate superconductors. For all the periods, we find that the modulated hopping inhomogeneity enhances the-wave pairing and an optimal inhomogeneity exists.