Phase diagram of the one-dimensional t-J model with long-range dipolar interactions

We study systematically the effect of long-range dipolar interactions on the groundstate phase diagram of the one-dimensional t-J model by means of the density matrix renormalization group. While the basic phases described by the Luttinger parameter K_ρ, namely, the repulsive Luttinger liquid (metallic phase, K_ρ < 1), attractive Luttinger liquid (superconducting phase, K_ρ > 1), and the phase separation (K_ρ →∞), are similar to those of the conventional t-J model, the presence of the long-range dipolar interactions leads to significant differences. i) At high-density regime, the phase boundaries of these three phases are even pushed to the large-J region; ii) at low-density regime, these phase boundaries shift toward the small-J region and, most importantly, iii) the spin-gap region spreads across the boundary of K_ρ = 1, suggesting an exotic metallic phase with spin-gap, which is absent in the conventional t-J model. The result indicates that the long-range dipolar interactions have a significant influence on the ground-state properties of the one-dimensional t-J model. Its implication on the pseudogap phenomenon of the hole-doped cuprates is briefly discussed.