Antiferromagnetic and Electric Polarized States in Two-Dimensional Janus Semiconductor Fe₂Cl₃I₃

Two-dimensional (2D) Janus semiconductors with mirror asymmetry exhibit novel properties, such as large spin-orbit coupling (SOC) and normal piezoelectric polarization, and have attracted great interest for their potential applications. Inspired by the recently fabricated 2D ferromagnetic (FM) semiconductor CrI3, a stable 2D (in x-y plane) antiferromagnetic (AFM) Janus semiconductor Fe2Cl3I3 with normal sublattice magnetization (mâ1z) is obtained using density functional theory calculations. By applying a tensile strain, the four magnetic states sequentially occur: AFM with mâ1z of the sublattice, AFM with mâ1xy of the sublattice, FM with mâ1xy, and FM with mâ1z. Such a novel magnetic phase diagram driven by strain can be well understood by the spin-spin interactions including the third nearest-neighbor hoppings with the single-ion anisotropy, in which the SOC of I atoms is found to play an essential role. In addition, the electric polarization of Fe2Cl3I3 is maintained under strain due to the broken inversion symmetry. Our results predict the rare Janus material Fe2Cl3I3 as an example of 2D semiconductors with both spin and charge polarizations and reveal the highly sensitive strain-controlled magnetic states and magnetization direction, which highlight the 2D magnetic Janus semiconductor as a new platform to design spintronic materials.