Novel spintronic device can store data in four stable states
Researchers from the University of Maryland, University of California, South Dakota School of Mines and Technology, East China Normal University, KAUST and other institutes recently reported all‑van der Waals multiferroic tunnel junctions (MFTJs) that combine ferromagnetism and ferroelectricity in a single nanoscale spintronic device, enabling four non‑volatile resistance states for multibit memory operation.
These multistate junctions are realized by vertically stacking three atomically thin crystals: two ferromagnetic electrodes and a ferroelectric tunnelling barrier, all obtained by mechanical exfoliation and then assembled into a clean, defect‑sparse heterostructure. In their prototypical structure, Fe3GeTe2/CuInP2S6/Fe3GeTe2, multilayer Fe3GeTe2 serves as the ferromagnetic electrodes, while CuInP2S6 (CIPS) provides a ferroelectric spacer with switchable polarization. Because the layers are coupled by van der Waals forces rather than epitaxial bonding, the stack avoids stringent lattice‑matching and chemical‑compatibility constraints that hinder oxide‑based MFTJs and is far less susceptible to interfacial defects and interdiffusion.