Atomic scale octahedral distortion and enhanced collective polarity underlying large polarization in ferroelectric perovskite oxides

Chemical doping represents a crucial and effective approach for controlling electricity and also many other properties, but the underlying mechanisms connecting dopant-induced structural evolutions to emergent functionalities remain incompletely understood. To address this knowledge gap, the atomic-level mechanism of the enhanced electric polarization in a typical perovskite ferroelectric oxide BiFeO 3 (BFO) is unveiled. B-site Mn-dopping, with bringing about atomic-level lattice and charge evolutions, clearly accelerates the local lattice distortion i.e. enhanced Fe/Mn displacement and (Fe/Mn)O 6 octahedral rotation. This facilitates large-scale polarization orientation alignment to create the enhanced collective polarity while manifesting an overall ferroelectric polarization of up to ∼160 μC/cm 2 . Local lattice distortion also promotes the Jahn-Teller effect because of the increasing proportion in Mn 3+ (3d 4 configuration) that could instigate symmetry-breaking stretching and bending distortions of (Fe/Mn)O 6 octahedra with showing improved magnetic moments. Our findings uncover the ferroelectricity-enhanced origination and offer a new paradigm for principally designing ferroelectric functions. • The atomic-scale mechanism shows clear correlations between dopant-induced lattice distortions and ferroelectric properties. • Mn doping enhances Fe/Mn off-centering and BO 6 octahedral rotation, boosting polarization to ∼160 μC/cm 2 . • Local Jahn-Teller distortions increase due to higher Mn 3+ content, leading to symmetry breaking and improved magnetic moments. • A framework for designing multifunctional ferroelectrics via B-site doping and lattice charge-spin coupling.