BiFeO₃, a single-phase multiferroic material, possesses several polymorphs and exhibits a strong sensitivity to strain. Recently, emergent strain engineering in BiFeO₃ thin films has attracted intense interest, which can overcome the confines of traditional strain engineering introduced through the mismatch between the film and substrate. In this review, we discuss emerging non-traditional strain engineering approaches to create new ground states and manipulate novel functionalities in multiferroic BiFeO₃ thin films. Through fabricating freestanding thin films, inserting an interface layer or utilizing thermal expansion mismatch, continuously tunable strain can be imposed beyond substrate limitations. Nanostructured evolution and defect introduction are discussed as efficient routes to introduce strain, promising for the development of new nanodevices. Ultrafast optical excitation, growth conditions and chemical doping driven strain are summarized as well. We hope this review will arouse the readers’ interest in this fascinating field.

BiFeO ₃是一种单相多铁性材料，具有几种多晶型物，并且对应变具有很强的敏感性。近来，BiFeO ₃薄膜中的紧急应变工程引起了人们的强烈兴趣，它可以克服由于薄膜与基底之间的不匹配而引入的传统应变工程的局限性。在这篇综述中，我们讨论了新兴的非传统应变工程方法，以创建新的基态并操纵多铁性BiFeO _3中的新颖功能。薄膜。通过制造独立的薄膜，插入界面层或利用热膨胀失配，可以施加超出基板限制的连续可调应变。讨论了纳米结构的演化和缺陷的引入，作为引入应变的有效途径，有望开发出新的纳米器件。还总结了超快光激发，生长条件和化学掺杂驱动的应变。我们希望这篇评论能引起读者对该领域的兴趣。