Chiral Molecular Intercalation Enables Light-Controlled 2D Multiferroic Heterostructures

Chiral materials and multiferroics offer symmetry-controlled electronic and magnetic functionalities, yet their integration in two-dimensional systems remains challenging due to the difficulty of simultaneously sustaining chirality, ferroelectricity, and ferromagnetism at practical temperatures. Here we introduce a chiral molecular intercalation strategy to construct chiral 2D multiferroics by inserting enantiomeric molecules into layered ferroelectric CuInP₂S₆ and ferromagnetic Fe₃GaTe₂. Molecular insertion reshapes the interfacial electrostatic environment, induces charge redistribution, and expands the interlayer spacing, resulting in enhanced ferroic order, including a 5-fold increase in magnetic anisotropy energy (0.35→1.6 meV/Fe) and strengthened ferroelectric polarization. The resulting chiral CIPS-FGT heterostructures exhibit robust room-temperature magnetoelectric coupling (∼4.8% magnetization modulation) and enable helicity-dependent control of ferroic states under circularly polarized light, producing a 54.4% resistance modulation. This work establishes molecular intercalation as a general strategy for engineering light-responsive 2D multiferroics for optically tunable magnetoelectric and spintronic devices.