Room-temperature multiferroicity in all-van der Waals heterostructures.

Multiferroics host simultaneous and coupled ferroic orders, allowing disparate external stimuli to induce abrupt transformations in their structures and properties. Creating multiferroicity in two-dimensional (2D) van der Waals (vdW) platforms would add the elements of strong quantum confinement, enhanced quasiparticle excitations, and wide tunability to the capabilities of these systems. In this work, we constructed vdW heterostructures of ferromagnetic triiron gallium ditelluride (Fe3GaTe2) and ferroelectric copper indium thiophosphate (CuInP2S6) to integrate their respective orders. We observed strong interferroic coupling at room temperature by demonstrating ferroelectrically reconfigurable magnetic anisotropy of 2D Fe3GaTe2. The interferroic magnetoelectricity diminished with increasing Fe3GaTe2 thickness, revealing the interfacial nature of heterostructure multiferroicity. Our discovery of all-vdW heterostructure multiferroicity opens the door to the artificial assembly of vdW layers for designer 2D multiferroics.