CHARGE AND SPIN STRUCTURES IN THE ONE-DIMENSIONAL T-J MODEL

The physics of the one-dimensional t-J model may be determined at J/t --> 0 (i.e., the U/t --> infinity limit of the repulsive Hubbard model) and at J/t = 2 with the use of the Bethe ansatz. To get a full understanding of the charge and spin correlation functions for all values of J/t, one has to resort to numerical methods. We have used two numerical methods (the world-line quantum Monte Carlo algorithm and the quantum transfer-matrix algorithm) to get information on charge and spin static structure factors, pairing correlations, and critical exponents. The (1 + 1)-dimensional classical system corresponding to the one-dimensional t-J model, on which the Monte Carlo technique is used, is identified to a fifteen-vertex model. We show that the t-J model undergoes phase separation at large values of J/t. Before phase separation, both critical exponents and pairing correlations in the extended s-wave channel favor the onset of superconductivity. For low values of J/t, the model shows a U/t --> infinity Hubbard-like character.