Structural Monoclinicity and Its Coupling to Layered Magnetism in Few-Layer CrI3

Xiaoyu Guo, Wencan Jin, Zhipeng Ye, Gaihua Ye, Hongchao Xie, Bowen Yang, Hyun Ho Kim, Shaohua Yan, Yang Fu, Shangjie Tian, Hechang Lei, Adam W. Tsen, Kai Sun, Jia An Yan, Rui He, Liuyan Zhao

Research output: Contribution to journalArticlepeer-review

Abstract

Using polarization-resolved Raman spectroscopy, we investigate layer number, temperature, and magnetic field dependence of Raman spectra in one- to four-layer CrI3. Layer-number-dependent Raman spectra show that in the paramagnetic phase a doubly degenerated Eg mode of monolayer CrI3 splits into one Ag and one Bg mode in N-layer (N > 1) CrI3 due to the monoclinic stacking. Their energy separation increases in thicker samples until an eventual saturation. Temperature-dependent measurements further show that the split modes tend to merge upon cooling but remain separated until 10 K, indicating a failed attempt of the monoclinic-to-rhombohedral structural phase transition that is present in the bulk crystal. Magnetic-field-dependent measurements reveal an additional monoclinic distortion across the magnetic-field-induced layered antiferromagnetism-to-ferromagnetism phase transition. We propose a structural change that consists of both a lateral sliding toward the rhombohedral stacking and a decrease in the interlayer distance to explain our experimental observations.

Original languageEnglish
Pages (from-to)10444-10450
Number of pages7
JournalACS Nano
Volume15
Issue number6
DOIs
StatePublished - Jun 22 2021

Keywords

  • 2D magnets
  • CrI
  • Raman spectroscopy
  • magnetic phase transition
  • spin-lattice coupling
  • stacking order

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