Averyanov Dmitry V, Sokolov Ivan S, Taldenkov Alexander N, Parfenov Oleg E, Tokmachev Andrey M, Storchak Vyacheslav G
National Research Center "Kurchatov Institute", Kurchatov Sq. 1, Moscow 123182, Russia.
Nanoscale. 2022 Sep 2;14(34):12377-12385. doi: 10.1039/d2nr02777a.
2D magnetic materials are at the forefront of research on fundamentals of magnetism; they exhibit unconventional phases and properties controlled by external stimuli. 2D magnets offer a solution to the problem of miniaturization of spintronic devices. A technological target of materials science is to find suitable magnetic materials and scale their thickness down as much as possible, a single monolayer being a natural limit. However, magnetism does not halt at one monolayer - it may persist beyond this boundary, to sparse but regular lattices of magnetic atoms. Here, we report 2D magnetic phases of Eu on the Ge(110) surface. We synthesized two submonolayer structures Eu/Ge(110) employing molecular beam epitaxy. The phases, identified by electron diffraction, differ in the surface density of Eu atoms. At low temperature, they exhibit magnetic ordering with magnetic moments lying in-plane. Strong dependence of the effective magnetic transition temperature on weak magnetic fields points at the 2D nature of the observed magnetism. The results are set against those on the Eu/Si system. The study of Eu/Ge(110) magnets demonstrates that a variety of substrates of different structure and symmetry can host submonolayer 2D magnetic phases, suggesting the phenomenon to be rather general.
二维磁性材料处于磁学基础研究的前沿；它们展现出由外部刺激控制的非常规相和特性。二维磁体为自旋电子器件的小型化问题提供了解决方案。材料科学的一个技术目标是找到合适的磁性材料并尽可能减小其厚度，单个单层是自然极限。然而，磁性并不止于一个单层——它可能会越过这个边界，延伸到稀疏但规则的磁性原子晶格。在此，我们报道了Eu在Ge(110)表面的二维磁相。我们采用分子束外延合成了两种亚单层结构的Eu/Ge(110)。通过电子衍射确定的这些相，在Eu原子的表面密度上有所不同。在低温下，它们表现出磁有序，磁矩位于平面内。有效磁转变温度对弱磁场的强烈依赖性表明所观察到的磁性具有二维特性。将这些结果与Eu/Si体系的结果进行了对比。对Eu/Ge(110)磁体的研究表明，各种不同结构和对称性的衬底都可以承载亚单层二维磁相，这表明该现象相当普遍。
