Wang Peng, Wen Yao, Zhao Xiaoxu, Zhai Baoxing, Du Ruofan, Cheng Mo, Liu Zheng, He Jun, Shi Jianping
The Institute for Advanced Studies, Wuhan University, Wuhan 430072, China.
Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China.
ACS Nano. 2022 May 24;16(5):8301-8308. doi: 10.1021/acsnano.2c02267. Epub 2022 Apr 25.
Two-dimensional (2D) iron chalcogenides (FeX, X = S, Se, Te) are emerging as an appealing class of materials for a wide range of research topics, including electronics, spintronics, and catalysis. However, the controlled syntheses and intrinsic property explorations of such fascinating materials still remain daunting challenges, especially for 2D nonlayered FeS with mixed-valence states and high conductivity. Herein, we design a general and temperature-mediated chemical vapor deposition (CVD) approach to synthesize ultrathin and large-domain FeS nanosheets on mica substrates, with the thickness down to ∼4.4 nm (2 unit-cell). Significantly, we uncover a quadratic-dependent unsaturated magnetoresistance (MR) with out-of-plane anisotropy in 2D FeS, thanks to its ultrahigh crystalline quality and high conductivity (∼2.7 × 10 S m at room temperature and ∼1.7 × 10 S m at 2 K). More interestingly, the CVD-synthesized 2D FeS nanosheets maintain robust environmental stability for more than 8 months. These results hereby lay solid foundations for synthesizing 2D nonlayered iron chalcogenides with mixed-valence states and exploring fascinating quantum phenomena.
二维铁硫族化合物（FeX，X = S、Se、Te）正成为一类极具吸引力的材料，适用于广泛的研究主题，包括电子学、自旋电子学和催化。然而，对于这类迷人材料的可控合成和本征性质探索仍然是艰巨的挑战，特别是对于具有混合价态和高导电性的二维非层状FeS。在此，我们设计了一种通用的、温度介导的化学气相沉积（CVD）方法，在云母衬底上合成超薄且大尺寸的FeS纳米片，其厚度低至约4.4 nm（2个晶胞）。值得注意的是，由于其超高的晶体质量和高导电性（室温下约为2.7×10 S m，2 K时约为1.7×10 S m），我们在二维FeS中发现了具有面外各向异性的二次依赖非饱和磁电阻（MR）。更有趣的是，通过CVD合成的二维FeS纳米片在超过8个月的时间里保持了强大的环境稳定性。这些结果为合成具有混合价态的二维非层状铁硫族化合物和探索迷人的量子现象奠定了坚实的基础。
