Ferroelectric tunnel junctions (FTJs) are very promising as a new type of nonvolatile memory devices due to the tunneling electroresistance (TER) effect. In recent years, with the rise of two-dimensional (2D) materials, 2D ferroelectrics and their application in FTJs have attracted intensive attention, with the advantage of greatly reducing the FTJ based memory device sizes, as demanded by the ongoing device minituriazation in modern electronic circuits. However, all present schemes for realizing giant TER ratio with 2D FTJs are based on the polarization reversal of the whole ferroelectric layer upon an electrical field. In this work, we explore the quantum transport properties of the 2D FTJs with the partial reversal of polarization, namely, the formation of domain walls (DWs) by constructing two kinds of FTJs. One is in a uniform-polarization state and the other one is a state with domain walls. Structural relaxation confirms the stability of the domain-wall state. By quantum transport calculation, we obtain a TER ratio as high as 2.75 × 10⁴%. Further analysis of the electronic structure shows that there is charge accumulation or charge depletion at the two DWs. Such asymmetric interface polarization charges result in a built-in electrical field and thus affect the distribution of the effective potential along the transport direction. This leads to partial metal-insulator transition around the DWs and finally the giant TER ratio. Our results indicate that DWs may greatly affect the quantum transport and provide a new mechanism for realizing giant TER effect in 2D FTJs.

铁电隧道结（FTJ）由于隧穿电阻（TER）效应，作为一种新型的非易失性存储设备非常有前途。近年来，随着二维（2D）材料的兴起，二维铁电体及其在FTJ中的应用引起了广泛的关注，其优点是极大地减小了基于FTJ的存储设备的尺寸，这是当前现代设备最小化的要求。电子电路。然而，目前所有用于利用2D FTJ实现巨大TER比的方案都是基于整个铁电层在电场作用下的极化反转。在这项工作中，我们探索了量子输运极化部分反转的二维FTJ的特性，即通过构造两种FTJ形成畴壁（DW）。一个处于均匀极化状态，另一个处于具有畴壁的状态。结构弛豫证实了畴壁状态的稳定性。通过量子输运计算，我们得出的TER比高达2.75×10 ⁴％。对电子结构的进一步分析表明，在两个DW处存在电荷积累或电荷耗尽。这种不对称的界面极化电荷会产生内置电场，从而影响有效电位沿传输方向的分布。这导致DW周围的部分金属-绝缘体过渡，并最终达到巨大的TER比。我们的结果表明，DWs可能极大地影响量子传输，并为实现2D FTJ中的巨大TER效应提供了新的机制。