Topological (Sliced) Doping of a 3D Peierls System: Predicted Structure of Doped BaBiO3

TL;DR

This paper predicts that in doped BaBiO3, topological stacking faults called slices can form at certain doping levels, influenced by Coulomb interactions, which modify the stability of bipolaronic defects.

Contribution

It introduces a topological defect model for doped BaBiO3, incorporating Coulomb effects to predict the formation of slices in the Peierls order.

Findings

Slices are predicted to form at around 30% doping.

Long-range Coulomb interactions destabilize slices at low doping.

Bipolarons remain stable at very dilute hole concentrations.

Abstract

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.