Distinct magneto-Raman signatures of spin-flip phase transitions in CrI3
Amber D. McCreary, Thuc T. Mai, Franz Utermohlen, Jeffrey R. Simpson, Kevin F. Garrity, Xiaozhou Feng, Dmitry Shcherbakov, Yanglin Zhu, Jin Hu, Daniel Weber, Kenji Watanabe, Takashi Taniguchi, Joshua Goldberger, Zhiqiang Mao, Chun Ning Lau, Yuanming Lu, Nandini Trivedi, Rolando Valdes Aguilar, Angela R. Hight Walker
The discovery of 2-dimensional (2D) materials, such as CrI3, that retain magnetic ordering down to monolayer thickness, and even more have layer-dependent magnetic properties has led to a plethora of research in 2D magnetism. Here, we report a magneto-Raman spectroscopy study on multilayered CrI3, especially focusing on two new modes which appear below the magnetic ordering temperature and have been previously attributed to magnons. Fascinatingly, we observe a striking evolution of the Raman spectra with applied magnetic field, with some modes disappearing and others appearing with increased magnetic field. Distinct jumps in the intensities of the modes follow jumps in recent magneto-tunneling measurements attributed to the interlayer exchange interaction changing from antiferromagnetic to ferromagnetic at a critical magnetic field. Our work highlights that Raman modes are highly sensitive to weak interlayer exchange coupling in CrI3, proving a diffraction-limited and non-contact technique to probe these spin-flip phase transitions. In addition, we offer potential origins for the new modes, which we deduce are not, in fact, magnons.