Interfacial work-function engineering for giant tunneling electroresistance in a Sc 2 CO 2 /Y 2 CO 2 van der Waals ferroelectric tunnel junction

Abstract Van der Waals ferroelectric tunnel junctions (FTJs) based on two-dimensional (2D) materials offer a promising platform for next-generation nonvolatile memory, yet achieving ultrahigh tunneling electroresistance (TER) remains a critical challenge. This work demonstrates a giant TER effect of 5.83 × 10 9 % in a vertically stacked FTJ comprising out-of-plane ferroelectric monolayers Sc 2 CO 2 and Y 2 CO 2 . First-principles calculations and quantum transport simulations reveal that the TER originates from interfacial work-function engineering. In the P ↓↓ state, a substantial work-function difference (Δ W = 2.35 eV) drives significant charge transfer and yielding high conductance. Conversely, the P ↓↑ configuration exhibits a smaller Δ W (0.85 eV), insufficient to overcome the Sc 2 CO 2 band gap. These findings not only propose Sc 2 CO 2 /Y 2 CO 2 as an exceptional candidate for high-performance memory devices but also establish a general interfacial design strategy for achieving colossal TER in low-dimensional ferroelectric systems.