Li Hao, Yang Yali, Deng Shiqing, Zhang Linxing, Cheng Sheng, Guo Er-Jia, Zhu Tao, Wang Huanhua, Wang Jiaou, Wu Mei, Gao Peng, Xiang Hongjun, Xing Xianran, Chen Jun
Beijing Advanced Innovation Center for Materials Genome Engineering, and Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China.
Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China.
Sci Adv. 2022 Apr;8(13):eabm8550. doi: 10.1126/sciadv.abm8550. Epub 2022 Apr 1.
The orthorhombic rare-earth manganates and ferrites multiferroics are promising candidates for the next generation multistate spintronic devices. However, their ferroelectric polarization is small, and transition temperature is far below room temperature (RT). The improvement of ferroelectricity remains challenging. Here, through the subtle strain and defect engineering, an RT colossal polarization of 4.14 μC/cm is achieved in SmFeO films, which is two orders of magnitude larger than its bulk and is also the largest one among the orthorhombic rare-earth manganite and ferrite family. Meanwhile, its RT magnetism is uniformly distributed in the film. Combining the integrated differential phase-contrast imaging and density functional theory calculations, we reveal the origin of this superior ferroelectricity in which the purposely introduced oxygen vacancies in the Fe-O layer distorts the FeO octahedral cage and drives the Fe ion away from its high-symmetry position. The present approach can be applied to improve ferroelectric properties for multiferroics.
正交晶系稀土锰酸盐和铁氧体多铁性材料是下一代多态自旋电子器件的有前途的候选材料。然而，它们的铁电极化较小，转变温度远低于室温（RT）。铁电性的改善仍然具有挑战性。在此，通过精细的应变和缺陷工程，在SmFeO薄膜中实现了4.14 μC/cm的室温巨极化，这比其体材料大两个数量级，也是正交晶系稀土锰酸盐和铁氧体家族中最大的。同时，其室温磁性在薄膜中均匀分布。结合积分差分相衬成像和密度泛函理论计算，我们揭示了这种优异铁电性的起源，即Fe-O层中特意引入的氧空位使FeO八面体笼畸变，并驱使Fe离子离开其高对称位置。目前的方法可用于改善多铁性材料的铁电性能。
