Control of magnetic transition, metal-semiconductor transition, and magnetic anisotropy in noncentrosymmetric monolayer Cr$_2$Ge$_2$Se$_3$Te$_3$

TL;DR

This study uses first-principles calculations to explore a noncentrosymmetric monolayer Cr2Ge2Se3Te3, revealing its tunable magnetic and electronic properties under strain and electric fields, including magnetic phase transitions and anisotropy control.

Contribution

It introduces a Janus ferromagnetic monolayer with inversion symmetry breaking and demonstrates its tunable magnetic and electronic properties via strain and electric field.

Findings

Ferromagnetic-antiferromagnetic transition under strain

Metal-semiconductor transition under strain

Magnetocrystalline anisotropy energy modulated by electric field and strain

Abstract

Recent advances in two-dimensional materials have greatly expanded the family of ferromagnetic materials. The well-known 2D ferromagnets, such as CrI$_3$, Cr$_2$Ge$_2$Te$_6$, and Fe$_3$GeTe$_2$ 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, Cr$_2$Ge$_2$Se$_3$Te$_3$ 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 Te$_3$ atoms play a key role in determining the MAE, where contributions are primarily from $p_z / p_y$ and $p_x / p_y$ 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.