Point defects at ferroelectric domain walls in hexagonal YMnO₃

Understanding how point defects influence the domain wall (DW) mobility and properties in ferroelectrics is desirable both to control the macroscopic ferroelectric properties and to develop DW-based nanoscale electronic circuitry. Here we use DFT calculations to study the interplay between neutral ferroelectric DWs in improper ferroelectric YMnO₃ and lattice imperfections like aliovalent dopant cations and oxygen defects like vacancies and interstitials. We find that the DW mobility and conductivity strongly couples to the defect chemistry of the material, and our simulations are supported by experimental reports. The overall aim of this study is to obtain chemical guidelines from first principles calculations for how to control the DW mobility and conductivity through defect chemistry. YMnO₃ displays great chemical flexibility, where donor and acceptor doping of both cation sublattices as well as both oxygen deficiency and excess is possible, making hexagonal manganites an ideal model system for this purpose.