Quantum Monte Carlo simulations of the t-Jz model with stripes on the square lattice

We have performed finite temperature quantum Monte Carlo simulations on the t-Jz model on the square lattice. An on-site potential, representing the effect of external mechanisms, is used to stabilize a state of straight site-centered stripes. We show in the first place that various results of our simulations can be related to features observed in high-Tc superconductors giving validity to our model. In particular, it is shown that only below a certain temperature the spin regions between stripes are in anti-phase corresponding to an "incommensurate" magnetic order. Then, we examine the hole-hole correlations concluding that in the presence of this kind of stripes no sign of attraction of holes is seen at the lowest temperatures we can reach. The consequences for several theories regarding the relationship between stripes and superconductivity are discussed.