Department of Electronic Systems, NTNU - Norwegian University of Science and Technology, 7491, Trondheim, Norway.
Department of Materials Science and Engineering, NTNU - Norwegian University of Science and Technology, 7491, Trondheim, Norway.
Sci Rep. 2017 Jun 29;7(1):4386. doi: 10.1038/s41598-017-04103-y.
Perovskite oxides are known for their strong structure property coupling and functional properties such as ferromagntism, ferroelectricity and high temperature superconductivity. While the effect of ordered cation vacancies on functional properties have been much studied, the possibility of tuning the functionality through anion vacancy ordering has received much less attention. Oxygen vacancies in ferromagnetic LaSrMnO thin films have recently been shown to accumulate close to interfaces and form a brownmillerite structure (ABO). This structure has alternating oxygen octahedral and tetrahedral layers along the stacking direction, making it a basis for a family of ordered anion defect controlled materials. We use density functional theory to study how structure and properties depend on oxygen stoichiometry, relying on a block-by-block approach by including additional octahedral layers in-between each tetrahedral layer. It is found that the magnetic and electronic structures follow the layers enforced by the ordered oxygen vacancies. This results in spatially confined electronic conduction in the octahedral layers, and decoupling of the magnetic sub-lattices in the octahedral and tetrahedral layers. These results demonstrate that anion defect engineering is a promising tool to tune the properties of functional oxides, adding a new avenue for developing functional oxide device technology.
钙钛矿氧化物以其强烈的结构-性能耦合和功能特性而闻名，如铁磁性、铁电性和高温超导性。虽然有序阳离子空位对功能特性的影响已经得到了广泛的研究，但通过阴离子空位有序来调整功能的可能性却受到了较少的关注。最近发现，铁磁 LaSrMnO 薄膜中的氧空位会在界面附近聚集并形成尖晶石结构（ABO）。这种结构沿堆积方向交替存在氧八面体和四面体层，为一系列有序阴离子缺陷控制材料提供了基础。我们使用密度泛函理论研究了结构和性质如何依赖于氧化学计量，通过在每个四面体层之间添加额外的八面体层来采用分块的方法。结果发现，磁性和电子结构遵循有序氧空位所施加的层。这导致了在八面体层中空间受限的电子传导，并在八面体和四面体层中的磁子晶格解耦。这些结果表明，阴离子缺陷工程是调整功能氧化物性质的一种很有前途的工具，为开发功能氧化物器件技术开辟了新途径。
