CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication , National Center for Nanoscience and Technology , Beijing 100190 , China.
State Key Laboratory of Electronic Thin Films and Integrated Devices , University of Electronic Science and Technology of China , Chengdu 610054 , China.
Nano Lett. 2019 Mar 13;19(3):2154-2161. doi: 10.1021/acs.nanolett.9b00386. Epub 2019 Feb 25.
Two-dimensional (2D) magnetic materials provide an ideal platform for the application in spintronic devices due to their unique spin states in nanometer scale. However, recent research on the exfoliated monolayer magnetic materials suffers from the instability in ambient atmosphere, which needs extraordinary protection. Hence the controllable synthesis of 2D magnetic materials with good quality and stability should be addressed. Here we report for the first time the van der Waals (vdW) epitaxial growth of one-unit-cell-thick air-stable ferrimagnet CrS semiconductor via a facile chemical vapor deposition method. Single crystal CrS with the domain size reaching to 200 μm is achieved. Most importantly, we observe the as grown CrS with a Néel temperature ( T) of up to 120 K and a maximum saturation magnetic momentum of up to 65 μemu. As the temperature decreases, the samples show a transition from soft magnet to hard magnet with the highest coercivity of 1000 Oe. The one-unit-cell-thick CrS devices show a p-type transfer behavior with an on/off ratio over 10. Our work highlights CrS monolayer as an ideal magnetic semiconductor for 2D spintronic devices. The vdW epitaxy of nonlayered magnets introduces a new route for realizing magnetism in 2D limit and provides more application potential in the 2D spintronics.
二维（2D）磁性材料由于其在纳米尺度上的独特自旋状态，为自旋电子器件的应用提供了理想的平台。然而，剥离的单层磁性材料的最近研究受到周围大气环境不稳定性的困扰，需要非凡的保护。因此，应该解决具有良好质量和稳定性的 2D 磁性材料的可控合成问题。在这里，我们首次通过简便的化学气相沉积方法报告了范德华（vdW）外延生长的具有一个单胞厚度的、空气稳定的亚铁磁 CrS 半导体。获得了尺寸达到 200 μm 的单晶 CrS。最重要的是，我们观察到所生长的 CrS 的尼尔温度（T）高达 120 K，最大饱和磁动量高达 65 μemu。随着温度的降低，样品表现出从软磁到硬磁的转变，最高矫顽力为 1000 Oe。具有一个单胞厚度的 CrS 器件表现出 p 型转移行为，开关比超过 10。我们的工作突出了 CrS 单层作为 2D 自旋电子器件的理想磁性半导体。非层状磁体的 vdW 外延为在 2D 极限中实现磁性提供了一条新途径，并为 2D 自旋电子学提供了更多的应用潜力。
