On electrically tunable stacking domains and ferroelectricity in moiré superlattices

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It is well known that stacking domains form in moir'e superlattices due to the competition between the interlayer van der Waals forces and intralayer elastic forces, which can be recognized as polar domains due to the local spontaneous polarization in bilayers without centrosymmetry. We propose a theoretical model which captures the effect of an applied electric field on the domain structure. The coupling between the spontaneous polarization and field leads to uneven relaxation of the domains, and a net polarization in the superlattice at nonzero fields, which is sensitive to the moir'e period. We show that the dielectric response to the field reduces the stacking energy and leads to softer domains in all bilayers. We then discuss the recent observations of ferroelectricity in the context of our model.


Funder: Cambridge Commonwealth, European and International Trust (Cambridge Commonwealth, European & International Trust); doi: https://doi.org/10.13039/501100003343

cond-mat.mes-hall, cond-mat.mes-hall
Journal Title
npj 2D Materials and Applications
Conference Name
Journal ISSN
Volume Title
Springer Science and Business Media LLC
EPSRC (1948657)
Engineering and Physical Sciences Research Council (EP/L015552/1)
D. B would like to thank E. Artacho and I. Lebedeva for helpful discussions. D. B acknowledges funding from the EPSRC Centre for Doctoral Training in Computational Methods for Materials Science under grant number EP/L015552/1. B. R gratefully acknowledges support from the Cambridge International Trust.