Cluster study of thet-Jmodel: Chiral fluctuations

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Abstract
Uniform and staggered chiral order are investigated in the two-dimensional t-J model at arbitrary doping fractions. Equal-time and dynamical correlations are calculated on a 4×4 cluster by using a Lanczos algorithm. We found that static uniform correlations are suppressed with increasing doping and t/J while static staggered correlations seem enhanced, in agreement with previous mean-field studies. The plaquette-plaquette correlation function falls off rapidly with distance, and, thus, we obtain an upper bound on the plaquette order parameter, which is very small. However, our numerical results show that doping for t/J≥1 induces large chiral fluctuations at low energy, which may become important even in the absence of long-range order. The staggered order parameter exhibits low-energy fluctuations of energy ∼2J, while for the uniform case fluctuations also occur at a higher energy ∼2t.