Two-dimensional (2D) ferromagnetic materials have been exhibiting promising potential in applications, such as spintronics devices. To grow epitaxial magnetic films on silicon substrate, in the single-layer limit, is practically important but challenging. In this study, we realized the epitaxial growth of MnSn monolayer on Si(111) substrate, with an atomically thin Sn/Si(111)-$2\sqrt{3}\times2\sqrt{3}$- buffer layer, and controlled the MnSn thickness with atomic-layer precision. We discovered the ferromagnetism in MnSn monolayer with the Curie temperature (Tc) of ~54 K. As the MnSn film is grown to 4 monolayers, Tc increases accordingly to ~235 K. The lattice of the epitaxial MnSn monolayer as well as the Sn/Si(111)-$2\sqrt{3}\times2\sqrt{3}$ is perfectly compatible with silicon, and thus an sharp interface is formed between MnSn, Sn and Si. This system provides a new platform for exploring the 2D ferromagnetism, integrating magnetic monolayers into silicon-based technology, and engineering the spintronics heterostructures.

中文翻译：

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硅衬底上外延生长的铁磁MnSn单层

二维 (2D) 铁磁材料在自旋电子器件等应用中表现出巨大的潜力。在单层限制下，在硅衬底上生长外延磁性薄膜实际上很重要但具有挑战性。在这项研究中，我们实现了 MnSn 单层在 Si(111) 衬底上的外延生长，具有原子级薄的 Sn/Si(111)-$2\sqrt{3}\times2\sqrt{3}$- 缓冲层，并控制具有原子层精度的 MnSn 厚度。我们发现了居里温度 (Tc) 为 ~54 K 的 MnSn 单层中的铁磁性。随着 MnSn 膜生长到 4 个单层，Tc 相应增加到 ~235 K。外延 MnSn 单层的晶格以及 Sn/ Si(111)-$2\sqrt{3}\times2\sqrt{3}$与硅完美兼容，因此在MnSn、Sn和Si之间形成了尖锐的界面。