Superconductivity from domain wall fluctuations in sliding ferroelectrics

Abstract

Bilayers of two-dimensional van der Waals materials that lack an inversion centre can show a novel form of ferroelectricity, where certain stacking arrangements of the two layers lead to an interlayer polarization. Under an external out-of-plane electric field, a relative sliding between the two layers can occur accompanied by an inter-layer charge transfer and a ferroelectric switching. We show that the domain walls that mediate ferroelectric switching are a locus of strong attractive interactions between electrons. The attraction is mediated by the ferroelectric domain wall fluctuations, effectively driven by the soft interlayer shear phonon. We comment on the possible relevance of this attraction mechanism to the recent observation of an interplay between sliding ferroelectricity and superconductivity in bilayer $\text{T$_d$-MoTe}_2$. We also discuss the possible role of this mechanism in the superconductivity of moir\'e bilayers.