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

ABSTRACT 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 NbB ₁₂ H ₆ monolayer as a representative example, in which the Jahn‐Teller effect drives the structural distortion. Crucially, reversing the ferroelectric polarization in the NbB ₁₂ H ₆ 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.