Shao Jian, Liu Hao, Zhang Kai, Yu Yang, Yu Weichao, Lin Hanxuan, Niu Jiebin, Du Kai, Kou Yunfang, Wei Wengang, Lan Fanli, Zhu Yinyan, Wang Wenbin, Xiao Jiang, Yin Lifeng, Plummer E W, Shen Jian
State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China; Department of Physics, Fudan University, Shanghai 200433, China;
State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China; Department of Physics, Fudan University, Shanghai 200433, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China;
Proc Natl Acad Sci U S A. 2016 Aug 16;113(33):9228-31. doi: 10.1073/pnas.1609656113. Epub 2016 Aug 1.
In complex oxides systems such as manganites, electronic phase separation (EPS), a consequence of strong electronic correlations, dictates the exotic electrical and magnetic properties of these materials. A fundamental yet unresolved issue is how EPS responds to spatial confinement; will EPS just scale with size of an object, or will the one of the phases be pinned? Understanding this behavior is critical for future oxides electronics and spintronics because scaling down of the system is unavoidable for these applications. In this work, we use La0.325Pr0.3Ca0.375MnO3 (LPCMO) single crystalline disks to study the effect of spatial confinement on EPS. The EPS state featuring coexistence of ferromagnetic metallic and charge order insulating phases appears to be the low-temperature ground state in bulk, thin films, and large disks, a previously unidentified ground state (i.e., a single ferromagnetic phase state emerges in smaller disks). The critical size is between 500 nm and 800 nm, which is similar to the characteristic length scale of EPS in the LPCMO system. The ability to create a pure ferromagnetic phase in manganite nanodisks is highly desirable for spintronic applications.
在诸如锰氧化物这样的复杂氧化物体系中，电子相分离（EPS）作为强电子关联的一个结果，决定了这些材料奇异的电学和磁学性质。一个基本但尚未解决的问题是EPS如何响应空间限制；EPS仅仅会随着物体尺寸缩放，还是其中一个相会被固定？理解这种行为对于未来的氧化物电子学和自旋电子学至关重要，因为对于这些应用而言，系统缩小是不可避免的。在这项工作中，我们使用La0.325Pr0.3Ca0.375MnO3（LPCMO）单晶盘来研究空间限制对EPS的影响。以铁磁金属相和电荷有序绝缘相共存为特征的EPS态似乎是体材料、薄膜和大尺寸圆盘的低温基态，而在较小的圆盘中出现了一种之前未被识别的基态（即单一铁磁相态）。临界尺寸在500纳米到800纳米之间，这与LPCMO体系中EPS的特征长度尺度相似。在锰氧化物纳米圆盘中形成纯铁磁相的能力对于自旋电子学应用来说是非常可取的。
