Using the density matrix renormalization group, we study domain wall
structures in the t-J model at a hole doping of x=1/8. We find that the domain
walls are composed of d_{x^2-y^2} pairs and that the regions between the domain
walls have antiferromagnetic correlations that are pi phase shifted across a
domain wall. At x=1/8, the hole filling corresponds to one hole per two domain
wall unit cells. When the pairs in a domain wall are pinned by an external
field, the d_{x^2-y^2} pairing response is suppressed, but when the pinning is
weakened, d_{x^2-y^2} pair-field correlations can develop.Comment: 11 pages, with 3 Postscript figure