Two-Dimensional Spin-Antiferroelectric Altermagnets with Giant Spin Splitting: From Model to Material Realization.

The realization of multiferroic altermagnets featuring giant intrinsic spin splitting holds great promise for next-generation spintronics. In this work, based on the recently proposed concept of spin-antiferroelectricity (spin-AFE), we construct a class of two-dimensional (2D) multiferroic altermagnets, termed 2D spin-antiferroelectric altermagnets (2D spin-AFEAMs), enabling electrical control of spin polarization via a gate field. Furthermore, we propose a general design strategy for constructing 2D spin-AFEAMs with large intrinsic spin splitting. Guided by this strategy, we predict monolayer (CoCl)2Te and its family materials as potential candidates of 2D spin-AFEAM. We uncover a highly tunable transport regime in monolayer (CoCl)2Te, where the spin current can be switched via the in-plane electric field angle when hole-doped and via the gate field polarity when electron-doped. Our work enriches the family of 2D multiferroics and provides a blueprint for realizing high-performance, electrically switchable altermagnetic spintronic devices.