Meng Meng, Sun Yuanwei, Li Yuehui, An Qichang, Wang Zhenzhen, Lin Zijian, Yang Fang, Zhu Xuetao, Gao Peng, Guo Jiandong
Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, China.
International Center for Quantum Materials, and Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, China.
Nat Commun. 2021 Apr 27;12(1):2447. doi: 10.1038/s41467-021-22790-0.
The d-band-filling of transition metals in complex oxides plays an essential role in determining their structural, electronic and magnetic properties. Traditionally, at the oxide heterointerface, band-filling control has been achieved via electrostatic modification in the structure of field-effect transistors or electron transfer, which is limited to the quasi-two-dimension at the interface. Here we report a three-dimensional (3D) band-filling control by changing the local lattice coordination in a designed oxide heterostructure. At the LaCoO/LaTiO heterointerface, due to the Fermi level mismatch, electrons transfer from LaTiO to LaCoO. This triggers destabilisation of the CoO octahedrons, i.e. the formation of lattice configurations with a reduced Co valence. The associated oxygen migration results in the 3D topotactic phase transition of LaCoO. Tuned by the thickness of LaTiO, different crystalline phases and band-fillings of Co occur, leading to the emergence of different magnetic ground states.
过渡金属在复合氧化物中的d带填充在决定其结构、电子和磁性特性方面起着至关重要的作用。传统上，在氧化物异质界面处，通过场效应晶体管结构中的静电修饰或电子转移来实现能带填充控制，这仅限于界面处的准二维情况。在此，我们报告了通过改变设计的氧化物异质结构中的局部晶格配位来实现三维（3D）能带填充控制。在LaCoO/LaTiO异质界面处，由于费米能级失配，电子从LaTiO转移到LaCoO。这引发了CoO八面体的不稳定，即形成了Co价态降低的晶格构型。相关的氧迁移导致LaCoO的三维拓扑相变。通过LaTiO的厚度进行调节，会出现不同的Co晶相和能带填充，从而导致不同的磁基态出现。
