Designing unconventional ferroelectrics in van der Waals heterostructures

Achieving atomically thin ferroelectric materials for the use in ferroelectric non-volatile memory remains a significant challenge in materials science, primarily due to the depolarization effects in ultra-thin scales. To address this challenge, we present a novel approach to engineer atomically thin ferroelectrics using van der Waals heterostructures. Our method involves artificially inducing ferroelectricity by manipulating the stacking angle of non-ferroelectric materials such as bilayer boron nitride and bilayer transition metal dichalcogenides. This technique enables us to produce one of the thinnest out-of-plane ferroelectrics that operates as a non-volatile memory at room temperature.



We specifically highlight its device performance as a ferroelectric field effect transistor. The artificial ferroelectrics offers atomically-thin devices that enables ultrafast and high-endurance switching, which outperforms some of the traditional constraints. This exceptional performance stems from the unique ferroelectric mechanism, where the polarization is switched by the interlayer sliding motion between the van der Waals layers.



Additionally, we introduce the novel concept of moiré ferroelectrics achieved by twisting the two layers. This results in a unique ferroelectric state characterized by an alternating out-of-plane polarization network. We further discuss the utility of moiré ferroelectrics as substrates to modulate the band structure of 2D materials in momentum space.