At hole concentrations below x=0.4, Ba_(1-x)K_xBiO_3 is non-metallic. At x=0, pure BaBiO3 is a Peierls insulator. Very dilute holes create bipolaronic point defects in the Peierls order parameter. Here we find that the Rice-Sneddon version of Peierls theory predicts that more concentrated holes should form stacking faults (two-dimensional topological defects, called slices) in the Peierls order parameter. However, the long-range Coulomb interaction, left out of the Rice-Sneddon model, destabilizes slices in favor of point bipolarons at low concentrations, leaving a window near 30% doping where the sliced state is marginally stable.
@article{arxiv.cond-mat/0203486,
title = {Topological (Sliced) Doping of a 3D Peierls System: Predicted Structure of Doped BaBiO3},
author = {Ilka B. Bischofs and Philip B. Allen and Vladimir N. Kostur and Rahul Bhargava},
journal= {arXiv preprint arXiv:cond-mat/0203486},
year = {2009}
}