Published June 25, 2021 | Version v1

Interfacial ferroelectricity by van der Waals sliding

Description

Despite their partial ionic nature, many-layered diatomic crystals avoid internal electric polarization
by forming a centrosymmetric lattice at their optimal 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 provide
intuitive insights to explore the interfacial polarization and its distinctive “slidetronics” switching
mechanism.

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