Magnetic anisotropy (MA) is a material preference that involves magnetization aligned along a specific direction and provides a basis for spintronic devices. Here we report the first observation of strong MA in a cobalt–molybdenum disulfide (Co/MoS₂) heterojunction. Element-specific magnetic images recorded with an X-ray photoemission electron microscope (PEEM) reveal that ultrathin Co films, of thickness 5 monolayers (ML) and above, form micrometer (μm)-sized domains on monolayer MoS₂ flakes of size tens of μm. Image analysis shows that the magnetization of these Co domains is oriented not randomly but in directions apparently correlated with the crystal structure of the underlying MoS₂. Evidence from micro-area X-ray photoelectron spectra (μ-XPS) further indicates that a small amount of charge is donated from cobalt to sulfur upon direct contact between Co and MoS₂. As the ferromagnetic behavior found for Co/MoS₂ is in sharp contrast with that reported earlier for non-reactive Fe/MoS₂, we suggest that orbital hybridization at the interface is what makes Co/MoS₂ different. Our report provides micro-magnetic and micro-spectral evidence that consolidates the knowledge required to build functional heterojunctions based on two-dimensional (2D) materials.

中文翻译：

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超薄Co / MoS2异质结中的自发感应磁各向异性。

磁各向异性（MA）是一种材料偏爱，它涉及沿特定方向排列的磁化强度，并为自旋电子器件提供了基础。在这里，我们报告了在钴-钼二硫化物（Co / MoS ₂）异质结中首次观察到强MA的现象。用X射线光发射电子显微镜（PEEM）记录的特定于元素的磁图像显示，厚度为5个单层（ML）以上的超薄Co膜在尺寸为10微米的单层MoS ₂薄片上形成了微米（μm）大小的畴。微米 图像分析表明，这些Co畴的磁化不是随机取向的，而是明显与下面的MoS ₂晶体结构相关的方向。来自微区X射线光电子能谱（μ-XPS）的证据进一步表明，在Co和MoS ₂直接接触时，钴中的少量电荷被带给了硫。由于发现Co / MoS ₂的铁磁行为与先前报道的非反应性Fe / MoS ₂的铁磁行为形成鲜明对比，我们建议界面处的轨道杂化是使Co / MoS ₂不同的原因。我们的报告提供了微磁和微光谱证据，巩固了基于二维（2D）材料构建功能异质结所需的知识。