Han Haojie, Zhang Qinghua, Li Wei, Liu Yiqun, Guo Jiasheng, Wang Yue, Li Qian, Gu Lin, Nan Ce-Wen, Ma Jing
State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Research (Wash D C). 2023 Jul 13;6:0191. doi: 10.34133/research.0191. eCollection 2023.
The oxygen octahedral rotation (OOR) forms fundamental atomic distortions and symmetries in perovskite oxides and definitely determines their properties and functionalities. Therefore, epitaxial strain and interfacial structural coupling engineering have been developed to modulate the OOR patterns and explore novel properties, but it is difficult to distinguish the 2 mechanisms. Here, different symmetries are induced in NaBiTiO (NBT) epitaxial films by interfacial oxygen octahedral coupling rather than epitaxial strain. The NBT film grown on the Nb:SrTiO substrate exhibits a paraelectric tetragonal phase, while with LaSrMnO as a buffer layer, a monoclinic phase and robust ferroelectricity are obtained, with a remanent polarization of 42 μC cm and a breakdown strength of 7.89 MV cm, which are the highest record among NBT-based films. Moreover, the interfacial oxygen octahedral coupling effect is demonstrated to propagate to the entire thickness of the film, suggesting an intriguing long-range effect. This work provides a deep insight into understanding the structure modulation in perovskite heterostructures and an important avenue for achieving unique functionalities.
氧八面体旋转（OOR）在钙钛矿氧化物中形成基本的原子畸变和对称性，并明确决定了它们的性质和功能。因此，人们已经开展了外延应变和界面结构耦合工程来调节OOR模式并探索新特性，但很难区分这两种机制。在此，通过界面氧八面体耦合而非外延应变在NaBiTiO（NBT）外延薄膜中诱导出不同的对称性。生长在Nb:SrTiO衬底上的NBT薄膜呈现顺电四方相，而以LaSrMnO作为缓冲层时，则获得单斜相和强铁电性，剩余极化强度为42 μC/cm²，击穿场强为7.89 MV/cm，这是基于NBT的薄膜中的最高记录。此外，界面氧八面体耦合效应被证明可传播至薄膜的整个厚度，表明存在一种有趣的长程效应。这项工作为理解钙钛矿异质结构中的结构调制提供了深刻见解，并为实现独特功能提供了一条重要途径。
