Computational dissection of single-layer intrinsic ferromagnetic semiconductor Mn2AX6 (A=Al, Ga; X=Cl, Br, I) with large magnetic anisotropy and high Curie temperature

Two-dimensional (2D) intrinsic ferromagnetic semiconductors (IFMS) have emerged as a pivotal research frontier in spintronics, uniquely enabling integration of semiconductor electronics with non-volatile magnetic storage at finite temperatures. Using first-principles calculations, we systematically investigated the structural stability, electronic, and magnetic properties of potential Mn2AX6 (A = Al, Ga; X = Cl, Br, I) materials with large-moment IFMS characteristics. Results confirm that these stable materials are indeed IFMS with an indirect bandgap ranging from 0.5 to 1.3 eV and a magnetization of 9 B/u.c. And their IFMS characteristics show exceptional resilience to strain. The semiconducting property transition to half-metal characteristic only when compressive strain exceeds 7% (as seen in Mn2AlCl6), while spin-polarized band inversion occurs when the strain shifts from compressive to tensile. Additionally, these monolayers consistently exhibit out-of-plane easy magnetization axes with magnetic anisotropy energy (MAE) of 0.028─2.1 meV and Curie temperatures (Tc) of 164─303 K. Further studies on magnetic mechanism reveal that their ferromagnetic ground states are predominantly governed by dxy─pxy─dxy superexchange interactions within Mn-X-Mn pathways near ~90°, with the concomitant high-Tc being attributable to the larger magnetic moments (~4.6 B) of Mn2+ and strong second- and third-nearest- neighbor Mn-Mn magnetic interactions compared to other transition metal (TM) dihalides. Collectively, these IFMS materials Mn2AX6, with advantages including strain-tunable spin flip and balanced magnetic properties, may exhibit greater potential than other TM halides for magnetic storage and magnetic sensor applications.