Ferroelectric Control of Spintronic and Valleytronic Properties in GdIBr/In2Se3 van der Waals Multiferroic Heterostructures.

Spin and valley degrees of freedom, as carriers of information in next-generation devices, remain a key focus for achieving controllable and nonvolatile electrical modulation. In this work, we design GdIBr/In2Se3 and GdBrI/In2Se3 van der Waals heterostructures that exhibit switchable bipolar magnetic semiconducting and quasi-half-metallic states under opposite ferroelectric polarizations. Notably, in the GdBrI/In2Se3 system, ferroelectric polarization switching enables reversible reorientation of the magnetic moment, transitioning from an in-plane alignment to a 45° canting. These effects originate from the built-in electric field and interfacial charge transfer modulated by ferroelectric polarization. Furthermore, both systems exhibit coexistence of valley polarizations that can be reversibly switched by ferroelectric polarization. This work positions these heterostructures as promising platforms for electrically tunable spintronic and valleytronic functionalities near room temperature.