Transition metal oxides (TMOs) are an important class of materials that show a wide range of functionalities involving spin, charge, and lattice degrees of freedom. The strong correlation between electrons in d-orbitals and the multivalence nature give rise to a variety of exotic electronic states ranging from insulator to superconductor and cause intriguing phase competition phenomena. Despite a burst of research on the multifarious functionalities in TMOs, little attention has been paid to the formation and integration of an electret—a type of quasi-permanent electric field generator useful for nanoscale functional devices as an electric counterpart to permanent magnets. Here, we find that an electret can be created in LaMnO₃ thin films by tip-induced electric fields, with a considerable surface height change, via solid-state electrochemical amorphization. The surface charge density of the formed electret area reaches ~400 nC cm⁻² and persists without significant charge reduction for more than a year. The temporal evolution of the surface height, charge density, and electric potential are systematically examined by scanning probe microscopy. The underlying mechanism is theoretically analyzed based on a drift-diffusion-reaction model, suggesting that positively charged particles, which are likely protons produced by the dissociation of water, play crucial roles as trapped charges and a catalysis to trigger amorphization. Our finding opens a new horizon for multifunctional TMOs.

过渡金属氧化物（TMO）是一类重要的材料，具有多种功能，涉及自旋，电荷和晶格自由度。d轨道中的电子与多价性质之间的强相关性导致了从绝缘体到超导体的各种奇异电子态，并引起了令人感兴趣的相竞争现象。尽管对TMO的多种功能进行了大量研究，但驻极体的形成和集成却很少受到关注。驻极体是一种准永久性电场发生器，可用于纳米级功能器件，作为永磁体的电气替代物。在这里，我们发现可以在LaMnO _3中创建驻极体通过固态电化学非晶化，由尖端感应电场产生的薄膜，其表面高度有相当大的变化。形成的驻极体区域的表面电荷密度达到〜400 nC cm ^-2，并且在没有明显减少电荷的情况下持续了一年以上。通过扫描探针显微镜系统地检查了表面高度，电荷密度和电势的时间演变。理论上基于漂移-扩散-反应模型分析了其潜在机理，表明带正电的粒子（可能是水解离产生的质子）起着关键作用，如俘获电荷和催化触发非晶化的作用。我们的发现为多功能TMO开辟了新的视野。