Superatom Distortion Induces Triferroicity and Spin Splitting in Two‐Dimensional Antiferromagnets

Triferroicity in two-dimensional (2D) materials provides an exceptional platform for multifunctional devices, yet combining a spin-splitting antiferromagnetic (AFM) state with ferroelectricity and ferroelasticity remains a formidable challenge. Here, we propose a general strategy to achieve concurrent ferroelectricity, AFM spin splitting, and ferroelasticity by incorporating superatoms into 2D lattices. We show that strong p-d orbital hybridization induces spontaneous symmetry-lowering distortions of superatoms, breaking inversion symmetry and stabilizing magnetic ordering. This mechanism enables the coexistence of these three ferroic orders-an effect that is difficult to achieve with conventional atomic building blocks. Using first-principles calculations, we identify the NbB12H6 monolayer as a representative example, in which the Jahn-Teller effect drives the structural distortion. Crucially, reversing the ferroelectric polarization in the NbB12H6 leads to a deterministic reversal of the AFM spin splitting, demonstrating robust magnetoelectric coupling. Moreover, this superatom-based multiferroic framework can be readily extended to a broad class of materials through the incorporation of alternative metals or superatomic motifs. Our findings establish superatom assembly as a powerful paradigm for designing 2D multiferroics with controllable spin degrees of freedom.