Magnetocrystalline Anisotropy Engineering of Magnon-Phonon Coupling in CrI₃ Monolayer

Abstract

The nonlinear magnon-phonon coupling enables magnetic materials promising platforms for fabricating phonon combs that are powerful tools for sensing, imaging, and quantum information applications. However, magnetocrystalline anisotropy, crucial for stabilizing two-dimensional (2D) magnetic materials, has been largely overlooked in magnon-phonon coupling studies. In this work, we incorporate magnetocrystalline anisotropy to evaluate the strength of magnon-phonon coupling in monolayer CrI₃. We find that the A_1u mode at ~157.75 cm^-1 exhibits the strongest magnon-phonon coupling (~2.6 cm^-1) arising from the large parallel movements along the out-of-plane direction (z-axis) of two magnetic Cr³⁺ ions. This mode corresponds to a large frequency shift of ~86.23 cm^-1 between the nonmagnetic and ferromagnetic phases. More interestingly, magnetocrystalline anisotropy exhibits mode-dependent effects on magnon-phonon coupling. Specifically, it enhances the coupling strength of the A_1u mode by 22.02%, while suppressing that of {\text{A}}_{1\text{g}}^2, {\text{A}}_{2\text{g}}^2 and {\text{E}}_{\text{g}}^2 modes by 69.68%, 55.9%, and 19.17%, respectively. These results identify magnetocrystalline anisotropy as a previously unexplored, symmetry-selective control knob for magnon-phonon coupling in 2D magnets.

Keywords

Magnon-phonon coupling / Magnetocrystalline anisotropy / 2D magnets / CrI₃ monolayer

RIGHTS & PERMISSIONS

Higher Education Press 2026

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