Magneto–Electric–Optical Coupling in Multiferroic BiFeO₃‐Based Films

Abstract Manipulating ferroic orders and realizing their coupling in multiferroics at room temperature are promising for designing future multifunctional devices. Single external stimulation has been extensively proved to demonstrate the ability of ferroelastic switching in multiferroic oxides, which is crucial to bridge the ferroelectricity and magnetism. However, it is still challenging to directly realize multi‐field‐driven magnetoelectric coupling in multiferroic oxides as potential multifunctional electrical devices. Here, novel magneto–electric–optical coupling in multiferroic BiFeO₃‐based thin films at room temperature mediated by deterministic ferroelastic switching using piezoresponse/magnetic force microscopy and aberration‐corrected transmission electron microscopy are shown. Reversible photoinduced ferroelastic switching exhibiting magnetoelectric responses is confirmed in BiFeO₃‐based films, which works at flexible strain states. This work directly demonstrates room‐temperature magneto–electric–optical coupling in multiferroic films, which provides a framework for designing potential multi‐field‐driven magnetoelectric devices such as energy conservation memories.