McCreary Amber, Mai Thuc T, Utermohlen Franz G, Simpson Jeffrey R, Garrity Kevin F, Feng Xiaozhou, Shcherbakov Dmitry, Zhu Yanglin, Hu Jin, Weber Daniel, Watanabe Kenji, Taniguchi Takashi, Goldberger Joshua E, Mao Zhiqiang, Lau Chun Ning, Lu Yuanming, Trivedi Nandini, Valdés Aguilar Rolando, Hight Walker Angela R
Nanoscale Device Characterization Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA.
Department of Physics, The Ohio State University, Columbus, OH, 43210, USA.
Nat Commun. 2020 Aug 3;11(1):3879. doi: 10.1038/s41467-020-17320-3.
The discovery of 2-dimensional (2D) materials, such as CrI, that retain magnetic ordering at monolayer thickness has resulted in a surge of both pure and applied research in 2D magnetism. Here, we report a magneto-Raman spectroscopy study on multilayered CrI, focusing on two additional features in the spectra that appear below the magnetic ordering temperature and were previously assigned to high frequency magnons. Instead, we conclude these modes are actually zone-folded phonons. We observe a striking evolution of the Raman spectra with increasing magnetic field applied perpendicular to the atomic layers in which clear, sudden changes in intensities of the modes are attributed to the interlayer ordering changing from antiferromagnetic to ferromagnetic at a critical magnetic field. Our work highlights the sensitivity of the Raman modes to weak interlayer spin ordering in CrI.
二维（2D）材料（如CrI）在单层厚度时仍保持磁有序性的发现，引发了二维磁性领域纯理论研究和应用研究的热潮。在此，我们报告了一项关于多层CrI的磁拉曼光谱研究，重点关注光谱中在磁有序温度以下出现的另外两个特征，这两个特征先前被归因于高频磁振子。相反，我们得出结论，这些模式实际上是区域折叠声子。我们观察到，随着垂直于原子层施加的磁场增加，拉曼光谱发生了显著演变，其中模式强度的明显突然变化归因于在临界磁场下，层间有序从反铁磁转变为铁磁。我们的工作突出了拉曼模式对CrI中弱层间自旋有序的敏感性。
