Strain tuned spin excitations in Janus Cr₂I₃Cl₃ monolayer

The Dzyaloshinskii-Moriya interaction (DMI) plays a key role in stabilizing noncollinear spin textures. However, the nearest-neighbor DMI is usually prohibited in certain hexagonal lattice materials due to the presence of inversion symmetry (IS). In this work, we numerically studied a Cr₂I₃Cl₃ Janus monolayer with a hexagonal structure in which the IS is broken. We found that the nearest-neighbor DMI, the Heisenberg interaction, along with the anisotropic Kitaev interaction in this material, can be tuned by biaxial strain. Moreover, our results reveal that an in-plane to out-of-plane ferromagnetic order transition occurs under tensile strain, while a spin-flop order can be regulated by compressive strain. In addition to magnetic phase transitions, we also find topological phase transitions in the magnon bands. We believe that the Janus structure tuned by the strain can serve as an ideal platform to study the magnetic properties and topological properties of magnon excitations.