The Mechanism of Strain Tunable Magnetic Anisotropy and Electronic Properties Ofbilayer Cri3

The bilayer CrI3 is of great interest for spintronics applications due to its unique interlayer antiferromagnetic ordering. In this study, we investigated the phase transition and magnetic anisotropy of bilayer CrI3 under both biaxial strain and uniaxial strain, ranging from compression to stretch. We found that interlayer coupling can be ferromagnetic (FM) or antiferromagnetic (AFM), depending crucially on applied strains. Under tensile strain, the interlayer AFM is enhanced across various strains, however, the phase transition point from AFM to FM varies for different compressive strains. Our comprehensive analysis of electronic structures reveals that both stretching and compression lead to a direct to indirect band gap transition. Additionally, our examination of magnetic anisotropic energy (MAE) indicates an out-of-plane easy axis for the entire range of strains, with perpendicular MAE mainly arising from iodine (I) atoms in an orbital and site-dependent manner. Finally, our investigation into magnetic moments and geometric structures confirms that the Cr-I-Cr angle smaller than 90 degree favors interlayer FM. These findings may have important implications for the development of novel 2D spintronic devices.