Intrinsic Multiferroic in VNI Monolayer

Two-dimensional (2D) multiferroic materials, exhibiting both ferromagnetism and ferroelasticity, have promising applications in the miniaturization of quantum devices, such as high-density data storage and spintronic devices. Using first-principles calculations, we propose a 2D material, a ternary, vanadium–nitride–halide compound VNI. Its dynamic, mechanical, and thermal stabilities are confirmed by phonon spectrum, elastic modulus, and molecular dynamics simulations. The VNI monolayer is a robust ferromagnetic metal with a sizable in-plane magnetic anisotropic energy (153 μeV per V atom). Meanwhile, the monolayer has a moderate ferroelastic switching barrier of 100.66 meV/atom, which would facilitate the fast ferroelastic dynamics under external stress. Notably, the magnetic anisotropy axis of the VNI monolayer can be adjusted from the a-axis to the b-axis through reversible ferroelastic strain, exhibiting the characteristics of magnetoelastic coupling. These results shed light on the design of nonvolatile-memory devices.