Fully Electrically Controlled Generation and Switching of Spin-Polarized Currents in van der Waals Multiferroic Heterostructures.

Achieving full electrical control of spin-polarized transport at the nanoscale remains a key challenge for spintronic technologies. Here, we demonstrate that integrating a ferroelectric layer into a ferromagnetic semiconductor sandwich structure enables nonvolatile generation and reversible switching of spin-polarized currents. Taking the Cr2Si2Te6/Sc2CO2/Cr2Ge2Te6 van der Waals multiferroic heterostructure as an example, our first-principles calculations show that by reversing the polarization direction of the intermediate ferroelectric layer, the heterostructure system can flexibly switch between spin-up and spin-down half-metallic states. This functionality originates from polarization-induced band shifts and interfacial charge transfer. Accordingly, the proposed multiferroic device exhibits a fully spin-polarized current with electrically switchable spin orientations and a perfect spin-filtering efficiency. Furthermore, we validated the effectiveness of this strategy in several other lattice-matched multiferroic heterostructures, thereby providing a new class of multiferroic systems with electrically switchable half-metallicity.