Distinct spin-lattice and spin-phonon interactions in monolayer magnetic CrI3

Lucas Webster, Liangbo Liang, Jia An Yan

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Abstract

We apply the density-functional theory to study various phases (including non-magnetic (NM), anti-ferromagnetic (AFM), and ferromagnetic (FM)) in monolayer magnetic chromium triiodide (CrI3), a recently fabricated 2D magnetic material. It is found that: (1) the introduction of magnetism in monolayer CrI3 gives rise to metal-to-semiconductor transition; (2) the electronic band topologies as well as the nature of direct and indirect band gaps in either AFM or FM phases exhibit delicate dependence on the magnetic ordering and spin-orbit coupling; and (3) the phonon modes involving Cr atoms are particularly sensitive to the magnetic ordering, highlighting distinct spin-lattice and spin-phonon coupling in this magnet. First-principles simulations of the Raman spectra demonstrate that both frequencies and intensities of the Raman peaks strongly depend on the magnetic ordering. The polarization dependent A1g modes at 77 cm-1 and 130 cm-1 along with the Eg mode at about 50 cm-1 in the FM phase may offer a useful fingerprint to characterize this material. Our results not only provide a detailed guiding map for experimental characterization of CrI3, but also reveal how the evolution of magnetism can be tracked by its lattice dynamics and Raman response.

Original languageEnglish
Pages (from-to)23546-23555
Number of pages10
JournalPhysical Chemistry Chemical Physics
Volume20
Issue number36
DOIs
StatePublished - 2018

Funding

We thank Dr. Joshua C. H. Lui and Rui He for sharing their experimental Raman data of few-layer CrI3 prior to publication. This work used the Extreme Science and Engineering Discovery Environment (XSEDE) Comet at the SDSC through allocation TG-DMR160101 and TG-DMR160088. L. W. and J. A. Y. acknowledge support from the NSF grant DMR 1709781 and support from the Fisher General Endowment and SET grants from the Jess and Mildred Fisher College of Science and Mathematics at Towson University. A portion of this research (Raman scattering modeling) used the computational package developed at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. L. L. was supported by Eugene P. Wigner Fellowship at the Oak Ridge National Laboratory and by the Center for Nanophase Materials Sciences.

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