Two-Dimensional Intrinsic Ferromagnetic Fe₃SSe₄ with Coexisting Half-Metallic and Quantum Anomalous Hall Effect

Two-dimensional (2D) topological half-metals (THMs) hold great potential for developing low-dissipation spintronics. Based on the structural derivation strategy inspired by experimentally synthesized quasi-2D kagome metals, we propose a promising 2D intrinsic ferromagnetic THM, the Fe₃SSe₄ monolayer, by first-principles calculations. Specifically, the stable Fe₃SSe₄ monolayer exhibits a robust ferromagnetic ground state with a Curie temperature of 210 K. It exhibits a sizable magnetic anisotropy energy of 3.72 meV per unit cell, significantly higher than that of several reported high-performance magnetic recording materials. Most strikingly, the calculated band structure reveals that the Fe₃SSe₄ system demonstrates coexisting half-metallicity and quantum anomalous Hall effect, characterized by a Chern number of C = 1. Furthermore, the Weyl cone is located very close to the Fermi level and is classified as type-I along the corresponding k path. The maximum Fermi velocity of 5.75 × 10⁵ m/s is higher than those of the 2D THMs reported to date. Our work would open up new opportunities for the design of other THMs.