Antiferromagnetic ferroelastic multiferroics in single-layer VOX (X = Cl, Br) predicted from first-principles

The realization of antiferromagnetic multiferroics is of great significance both for fundamental perspective and for potential use in nanoscale devices. Although almost all the known multiferroics in three-dimensional systems are antiferromagnetic, antiferromagnetic multiferroics is rarely explored in 2D lattice. Here, using first-principles calculations, we report the identification of 2D antiferromagnetic ferroelastic multiferroics in single-layer transition-metal oxyhalides VOX (X = Cl, Br). Both systems are robust antiferromagnetic semiconductors with a wide bandgap and exhibit an in-plane magnetization orientation. Also they possess extraordinary ferroelasticity with high ferroelastic transition signal and moderate switching barrier. Moreover, the antiferromagnetic and ferroelastic orders in them can be coupled together, leading to the exotic ferroelastic control of in-plane magnetic anisotropy. These phenomena and insights are useful for the fundamental research in antiferromagnetic multiferroics and would enable a wide range of applications in nanodevices.