Two-dimensional ferroelectrics can maintain vertical polarization up to room temperature, and are, therefore, promising for next-generation nonvolatile memories. Although natural two-dimensional ferroelectrics are few, moir\'{e} superlattices provide us with a generalized method to construct ferroelectrics from non-ferroelectric parent materials. We report a realization of ferroelectric hysteresis in a AB-BA stacked twisted double bilayer graphene (TDBG) system. The ferroelectric polarization is prominent at zero external displacement field and reduces upon increasing displacement fields. TDBG in the AB-BA configuration possesses a superlattice of non-centrosymmetric domains, exhibiting alternatively switchable polarities even without the assistance of any boron nitride layers; however, in the AB-AB stacking case, the development of polarized domains necessitates the presence of a second superlattice induced by the adjacent boron nitride layer. Therefore, twisted multilayer graphene systems offer us a fascinating field to explore two-dimensional ferroelectricity.
@article{arxiv.2404.18059,
title = {Ferroelectricity in twisted double bilayer graphene},
author = {Renjun Du and Jingkuan Xiao and Di Zhang and Xiaofan Cai and Siqi Jiang and Fuzhuo Lian and Kenji Watanabe and Takashi Taniguchi and Lei Wang and Geliang Yu},
journal= {arXiv preprint arXiv:2404.18059},
year = {2024}
}