Interfacial ferroelectricity by van der Waals sliding

Despite their ionic nature, many layered diatomic crystals avoid internal electric polarization by forming a centrosymmetric lattice at optimal anti-parallel van-der-Waals stacking. Here, we report stable ferroelectric order emerging the interface between two naturally-grown flakes of hexagonal-boron-nitride, which are stacked together in metastable non-centrosymmetric parallel orientation. We observe alternating domains inverted normal polarization, caused lateral shift one site domains. Reversible switching coupled to sliding is achieved scanning biased tip above surface. Our calculations trace origin phenomenon subtle interplay charge redistribution and displacement, our minimal cohesion model predicts further venues explore unique "slidetronics" switching.