Engineering Antiferroelectric Domains in Multiferroic Films by Epitaxial Strain

Antiferroelectric (AFE) materials offer great potential for diverse applications, yet achieving deterministic control over their domains remains a grand challenge. Here, using La-doped BiFeO₃ (LBFO) as a model, we demonstrate selective control over the different variants of AFE domains. This is inherently correlated to the orthorhombic structure of AFEs, which exhibits long and short axes of the unit cell. When growing on substrates with lattice larger than the long axis, tensile strain promotes a single structural domain with AFE order within the film plane. In contrast, compressive strain, imposed by substrates with lattice smaller than the short axis, stabilizes a two-domain state with AFE order inclined toward the out-of-plane direction. For substrates with intermediate lattice, the coexistence of multiple domain variants is realized. Our findings establish a general strain-based strategy to manipulate AFE domains, offering fundamental insights and a viable pathway to enhance the performance of AFE-based functional devices.