Stripe stability in doped antiferromagnets

In the framework of the t-J(chi) we discuss localized spin polarons for var ious original hole arrangements in different spin backgrounds. According to the so-called string picture we assume that local destruction in the magne tic structure caused by hole motion tends to localize holes and acts on the m as a kind of well potential. We concentrate on the case of the hole conce ntration 1/8 for which stripes are experimentally observed. We explicitly t ake into account interaction between holes and consider several possible co nfigurations, that represent: holes homogeneously distributed in the antife rromagnetic background, hole pairs (which correspond to spin bipolarons) ho mogeneously distributed in the antiferromagnetic background, hole pairs whi ch form the stripe structure in the perfect antiferromagnetic background, a nd eventually holes in stripes which separate antiferromagnetic domains wit h alternating direction of the staggered magnetization. Spin potarons are c onstructed by means of some computer algebra. It turns out that lowest eige nenergy has a state that represents a single hole polaron at the anti-phase domain wall (ADW). On the other hand, the stripe phase is exposed to keen competition from holes binding in the antiferromagnetic background and the energy margin by which stripes win is small.