First-principles prediction of a room-temperature ferromagnetic and ferroelastic 2D multiferroic MnNX (X = F, Cl, Br, and I)

Two-dimensional (2D) multiferroic materials have great potential applications in multifunctional nanoelectronics devices. Here, we construct a series of stable and isolated monolayers as 2D manganese nitrohalides MnNX (X = F, Cl, Br, and I) and systematically investigate the structural, electronic and magnetic properties using first-principles and Monte Carlo simulations. We find that ground states simultaneously show in-plane ferroelasticity and room-temperature ferromagnetic properties. We also reveal that the in-plane magnetic anisotropy can be tunable by the uniaxial ferroelastic strain. Our results will provide significant implications for future experiments and the design of new functional materials at the nanoscale.