Prediction of a multifunctional hexagonal Fe ₂ O ₃ monolayer with chiral antiferromagnetism and piezoelectricity

Two-dimensional (2D) materials that exhibit magnetism and piezoelectricity offer exciting opportunities for next-generation spintronic and multifunctional devices. The recently synthesized 2D hexagonal Fe2O3 provides a promising platform [Nat. Mater. 20, 1073 (2021)], yet its atomic structure remains unidentified. Herein, we report that high-throughput first-principles screening reveals a viable monolayer structure that can serve as a candidate for experimental realization. The proposed hexagonal Fe2O3 monolayer features a large direct band gap of 3.1 eV and hosts a robust chiral antiferromagnetic order stabilized by the interplay between triangular-lattice-induced geometric frustration and strong magnetic anisotropy. The absence of inversion symmetries gives rise to a pronounced in-plane piezoelectric response, with a d11 coefficient of −29.51 pm/V. Remarkably, these key electronic, magnetic, and piezoelectric properties remain robust under biaxial strain, highlighting the hexagonal Fe2O3 monolayer as a multifunctional candidate for piezoelectrically engineered spintronic applications.