Mechanisms for point defect-induced functionality in complex perovskite oxides

Perovskite oxides are an extremely versatile class of materials in which functionality can, besides other routes, also be engineered via the deliberate introduction of defects. In this focused review, we will specifically look at mechanistic details of ferroelectric and magnetic functionality introduced, altered, or reinforced by point defects. An ever-growing number of related studies start to provide a basis for the mechanistic understanding of different engineering routes to be exploited in future studies. Nevertheless, this review highlights that the effect of defects is not always easily predicted, given the delicate balance of lattice, charge, spin, and orbital degrees of freedom inherent to the perovskite structure. Systematic studies across various chemistries are thus still very much needed to obtain a more complete basis for defect-engineering ferroelectric and magnetic functionality in perovskite oxides.