Multiferroic monolayers VOX (X = Cl, Br, I): Tunable ferromagnetism via charge doping and ferroelastic switching

The fascinating properties arising from the interaction between different ferroic states of two-dimensional (2D) materials have inspired tremendous research interest in the past few years. Under the first-principles calculations, we predict the coexistence of antiferromagnetic and ferroelastic states in VO X ( X = Cl, Br, I) monolayers. The results illustrate that the VO X monolayers exhibit indirect bandgap characteristics, i.e. , their gaps decrease with the halide elements changing from Cl to I. The ground states of all these VO X monolayers are antiferromagnetic (AFM) with the magnetic moments contributed by the V 3d electrons. Furthermore, the magnetic ground state changing from AFM to ferromagnetism (FM) can be realized by doping carriers. In addition, the moderate ferroelastic transition barrier and reversible switching signal ensure their high performances of nonvolatile memory devices. Our findings not only offer an ideal platform for investigating the multiferroic properties, but also provide candidate materials for potential applications in spintronics.