Control of magnetic transition, metal–semiconductor transition, and magnetic anisotropy in noncentrosymmetric monolayer Cr2Ge2Se3Te3

Recent advances in two-dimensional materials have greatly expanded the family of ferromagnetic materials. The well-known 2D ferromagnets, such as CrI3, Cr2Ge2Te6, and Fe3GeTe2 monolayers, are characterized by centrosymmetric crystal structures. In contrast, ferromagnetic ordering in 2D noncentrosymmetric materials remains an underexplored area. Here, we report a Janus ferromagnet, Cr2Ge2Se3Te3 with inversion symmetry breaking, through first-principles calculations. This monolayer can undergo a ferromagnetic–antiferromagnetic transformation and a metal–semiconductor transition under different strains. Additionally, the strength of magnetocrystalline anisotropy energy (MAE) can be modulated by electric field or strain. In particular, the magnetization easy axis can be altered from in-plane to out-of-plane under strain. We find that Te3 atoms play a key role in determining the MAE, where contributions are primarily from pz/py and px/py orbitals. This study of Janus ferromagnetic materials has provided a promising platform for the research on the control of magnetism by strain or electric field.