Reversible control over the distribution of chemical inhomogeneities in multiferroic BiFeO₃

Despite the appeal of flawless order, semiconductor technology has demonstrated that implanting inhomogeneities into single-crystalline materials is pivotal for modern electronics. However, the influence of the local arrangement of chemical inhomogeneities on the material's functionalities is underexplored. In this work, we control the distribution of chemical inhomogeneities in La³⁺-substituted ferroelectric BiFeO₃ thin films. By means of a stress- and composition-driven phase transition, we trigger the formation of a lattice of La³⁺-rich and La³⁺-poor layers. This ordering correlates with the emergence of an antipolar phase. An electric field restores the original ferroelectric phase and re-randomizes the distribution of the La³⁺ inhomogeneities. Leveraging these insights, we tune the polar/antipolar phase coexistence to set the net polarization of La_0.15Bi_0.85FeO₃ to any desired value between its saturation limits. Finally, we control the net polarization response in device-compliant capacitor heterostructures to show that inhomogeneity-distribution control is a valuable tool in the design of functional oxide electronics.