Jin Zhitong, Ji Zijie, Zhong Yunlei, Jin Yunmin, Hu Xianyu, Zhang Xingxing, Zhu Lijing, Huang Xianhui, Li Tao, Cai Xinghan, Zhou Lin
School of Chemistry and Chemical Engineering, Frontiers Science Centre for Transformative Molecules, Shanghai Jiao Tong University, Shanghai 200240, China.
National Key Laboratory of Science and Technology on Micro/Nano Fabrication, Department of Micro/Nano Electronics, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
ACS Nano. 2022 May 24;16(5):7572-7579. doi: 10.1021/acsnano.1c11018. Epub 2022 Apr 20.
Two-dimensional (2D) magnetic materials provide an ideal platform for spintronics, magnetoelectrics, and numerous intriguing physical phenomena in 2D limits. Moiré superlattices based on 2D magnets offer an avenue for controlling the spin degree of freedom and engineering magnetic properties. However, the synthesis of high-quality, large-grain, and stable 2D magnets, much less obtaining a magnetic moiré superlattice, is still challenging. We synthesize 2D ferromagnets (trigonal CrTe) with controlled thickness and robust stability through chemical vapor deposition. Single-unit-cell-thick flakes with lateral sizes of tens of micrometers are obtained. We observe the layer-by-layer growth mode for the crystal formation in non-van der Waals CrTe. The robust anomalous Hall signal confirms that CrTe of varying thickness have a long-range ferromagnetic order with an out-of-plane easy axis. There is no obvious change of the Curie temperature when the thickness of CrTe decreases from 52.1 to 7.2 nm. Here, we construct diverse 2D non-van der Waals/van der Waals vertical heterostructures (CrTe/graphene, CrTe/h-BN, CrTe/MoS). A uniform moiré superlattice is formed in the heterostructure through a lattice mismatch. The successful growth of 2D CrTe and a related moiré superlattice introduces 2D non-van der Waals ferromagnets into moiré superlattice research, thus highlighting prospects for property investigation of a non-van der Waals magnetic moiré superlattice and massive applications which require a scalable approach to magnetic moiré superlattices.
二维（2D）磁性材料为自旋电子学、磁电学以及二维极限下众多引人入胜的物理现象提供了一个理想平台。基于二维磁体的莫尔超晶格为控制自旋自由度和设计磁性能提供了一条途径。然而，高质量、大晶粒且稳定的二维磁体的合成，更不用说获得磁性莫尔超晶格，仍然具有挑战性。我们通过化学气相沉积合成了具有可控厚度和强稳定性的二维铁磁体（三角CrTe）。获得了横向尺寸为几十微米的单胞厚度薄片。我们观察到非范德华CrTe晶体形成的逐层生长模式。强反常霍尔信号证实，不同厚度的CrTe具有沿面外易轴的长程铁磁序。当CrTe的厚度从52.1纳米减小到7.2纳米时，居里温度没有明显变化。在此，我们构建了多种二维非范德华/范德华垂直异质结构（CrTe/石墨烯、CrTe/h-BN、CrTe/MoS）。通过晶格失配在异质结构中形成了均匀的莫尔超晶格。二维CrTe和相关莫尔超晶格的成功生长将二维非范德华铁磁体引入到莫尔超晶格研究中，从而突出了对非范德华磁性莫尔超晶格进行性能研究以及对需要可扩展方法制备磁性莫尔超晶格的大量应用的前景。
