Wang Qing, Lu Qinwen, Zhang Xingmin, Xiang Liuzhi, Cheng Long, Li Xiaolong, Zhou Hua, Zhai Xiaofang
School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China.
High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei 230031, China.
ACS Appl Mater Interfaces. 2024 Dec 11;16(49):68197-68203. doi: 10.1021/acsami.4c14945. Epub 2024 Nov 25.
The water-liftoff fabrication of freestanding oxide membranes at nanometer-scale thickness marks a major breakthrough in expanding the family of soft electromagnetic materials. The structure reconstruction in the newly formed two-dimensional freestanding membrane due to the chemical liftoff provides an excellent opportunity to achieve applicable functionalities. In this report, we present the anisotropic relaxation of a LaMnO epitaxial film into a nearly wrinkle- and crack-free membrane, realized by high-temperature (160 °C)-treated PMMA as the protective layer during the water liftoff process. Remarkably, the resulting membrane exhibits a 2-fold uniaxial magnetic anisotropy, which is in stark contrast to the typical 4-fold biaxial magnetic anisotropy in biaxially strained epitaxial thin films. By performing half-order synchrotron X-ray diffraction experiments, the membrane is found to exhibit almost unvaried Mn-O bond lengths but uniaxially enlarged Mn-O-Mn bond angles, agreeing with the uniaxial magnetic anisotropy. Our study paves the way for engineering macroscopically high-quality membranes free of wrinkles and cracks, unlocking emergent electromagnetic properties that are essential for the integration and application of functional devices.
纳米级厚度的独立氧化物膜的水剥离制备标志着软电磁材料家族扩展方面的一项重大突破。由于化学剥离，新形成的二维独立膜中的结构重构为实现适用功能提供了绝佳机会。在本报告中，我们展示了通过在水剥离过程中使用高温（160°C）处理的聚甲基丙烯酸甲酯（PMMA）作为保护层，将LaMnO外延膜各向异性弛豫成几乎无皱纹和无裂纹的膜。值得注意的是，所得膜表现出2倍的单轴磁各向异性，这与双轴应变外延薄膜中典型的4倍双轴磁各向异性形成鲜明对比。通过进行半阶同步加速器X射线衍射实验，发现该膜的Mn - O键长几乎不变，但Mn - O - Mn键角单轴增大，这与单轴磁各向异性一致。我们的研究为制造宏观上高质量的无皱纹和无裂纹的膜铺平了道路，解锁了对于功能器件的集成和应用至关重要的新兴电磁特性。
