Two-dimensional (2D) intrinsic half-metal materials facilitate spin filtering, low-energy dissipation, and enhanced signal integrity, making them highly desirable for next-generation nanoelectronics and quantum technologies. In this work, we constructed two novel 2D half-metallic materials, α1-ScSi2N4 and α2-ScSi2N4, with unconventional ferromagnetism originating from N atoms rather than the transition metal Sc. First-principles calculations confirm their dynamic and thermal stability, as well as their intrinsic half-metallicity. We further demonstrate that their electronic and optical properties can be effectively tuned via strain, atomic adsorption, and external electric fields. A half-metal-to-metal transition occurs under compressive strain (α1: 10%; α2: 6–10%), while H/F adsorption induces a metallic state in α1, and H adsorption does so in α2. Furthermore, α1 becomes metallic at electric fields of −0.2 to −0.5 V/Å and 0.2 to 0.5 V/Å, while α2 undergoes a similar transition at electric fields of −0.3 to −0.5 V/Å and 0.3 to 0.5 V/Å. Both materials exhibit strong deep-ultraviolet absorption, indicating their potential in optoelectronic applications. Symmetry breaking, charge transfer, and energy level shifting may serve as tunable mechanisms driving the transition from half-metal to metal. These findings not only expand the family of two-dimensional half-metals with nonmetal-dominated magnetism but also potentially open new avenues for the design of tunable magnetic materials in reconfigurable electronic, spintronic, and photonic devices.
Liu et al. (Mon,) studied this question.