Despite their ionic nature, many layered diatomic crystals avoid internal electric polarization by forming a centrosymmetric lattice at their optimal anti-parallel van-der-Waals stacking. Here, we report a stable ferroelectric order emerging at the interface between two naturally-grown flakes of hexagonal-boron-nitride, which are stacked together in a metastable non-centrosymmetric parallel orientation. We observe alternating domains of inverted normal polarization, caused by a lateral shift of one lattice site between the domains. Reversible polarization switching coupled to lateral sliding is achieved by scanning a biased tip above the surface. Our calculations trace the origin of the phenomenon to a subtle interplay between charge redistribution and ionic displacement, and our minimal cohesion model predicts further venues to explore the unique "slidetronics" switching.
@article{arxiv.2010.05182,
title = {Interfacial Ferroelectricity by van-der-Waals Sliding},
author = {Maayan Vizner Stern and Yuval Waschitz and Wei Cao and Iftach Nevo and Kenji Watanabe and Takashi Taniguchi and Eran Sela and Michael Urbakh and Oded Hod and Moshe Ben Shalom},
journal= {arXiv preprint arXiv:2010.05182},
year = {2021}
}