Anionic Strategy-Modulated Magnetic Ordering in Super-elongated Multiferroic Epitaxial Films

Magnetic ordering of perovskite ferroelectric oxides is crucial for enhancing their stability and minimizing energy losses in magnetoelectric devices. However, inducing a transition from a magnetically disordered state to an ordered one remains a formidable challenge. Here, we propose a chemical sulfurization method that significantly enhances the magnetic ordering of multiferroic super-tetragonal phase BiFeO₃ thin film. The out-of-plane and in-plane magnetization significantly increases after sulfurization, accompanied by a rotation of the magnetic easy axis. X-ray absorption spectroscopy and spherical aberration transmission electron microscopy reveal the reconfiguration of local electronic hybridization states, restructuring Fe-O hybridization from pyramid-like FeO₅ to octahedral FeO₆ geometries. This transformation is considered the root cause of the observed magnetic transition in the films. This sulfur-induced strategy for electronic hybridization reconfiguration is expected to break new ground, offering innovative methodologies for modulating perovskite oxides, two-dimensional ferroelectric films, and other ferromagnetic functional thin films.