SINGLET STRIPE PHASES IN THE PLANAR T-J MODEL

The dimensional crossover of coupled t-J ladders to a planar model is examined using a mean-field approach with coupling constants determined by numerical diagonalization. Having a finite spin gap, uncoupled ladders belong to the Luther-Emery class in one-dimensional fermion systems, leading to a different crossover from coupling chains. For a wide region around J/t1 the hole-hole correlations in a single ladder are found to be predominantly charge-density-wave type, but an attraction between hole pairs on adjacent ladders leads to a stripe phase. A quantum-mechanical melting of the hole lines at J/t1 leads to a Bose condensate of hole pairs, i.e., a superconducting phase. © 1995 The American Physical Society.