Micromagnetometry of two-dimensional ferromagnets
Micromagnetometry of two-dimensional ferromagnets
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DOI：
10.1038/s41928-019-0302-6
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发表时间：
2019-10-01
影响因子：
34.3
通讯作者：
Geim, A. K.
中科院分区：
文献类型：
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作者：
Kim, M.;Kumaravadivel, P.;Geim, A. K.
对原子级薄铁磁晶体的研究发现了不寻常的磁性行为，并提供了对大块材料磁性的深入了解。然而，用于探索此类材料中铁磁性的实验技术无法直接探测磁场。在这里，我们表明，弹道霍尔微磁学可用于测量单个二维铁磁体的磁化强度。我们的设备是由货车的范德华组装在这样一种方式，即研究的铁磁晶体被放置在一个多终端霍尔棒由封装的石墨烯制成的顶部。本文用微磁技术研究了原子级三溴化铬（CrBr_3）。我们发现，该材料仍然是铁磁性的单层厚度，并表现出较强的面外各向异性。我们还发现，CrBr 3的磁响应随层数变化不大，其温度依赖性不能用二维铁磁性的简单伊辛模型来描述。
The study of atomically thin ferromagnetic crystals has led to the discovery of unusual magnetic behaviour and provided insight into the magnetic properties of bulk materials. However, the experimental techniques that have been used to explore ferromagnetism in such materials cannot probe the magnetic field directly. Here, we show that ballistic Hall micromagnetometry can be used to measure the magnetization of individual two-dimensional ferromagnets. Our devices are made by van der Waals assembly in such a way that the investigated ferromagnetic crystal is placed on top of a multi-terminal Hall bar made from encapsulated graphene. We use the micromagnetometry technique to study atomically thin chromium tribromide (CrBr3). We find that the material remains ferromagnetic down to monolayer thickness and exhibits strong out-of-plane anisotropy. We also find that the magnetic response of CrBr3 varies little with the number of layers and its temperature dependence cannot be described by the simple Ising model of two-dimensional ferromagnetism.