Superconductivity from domain wall fluctuations in sliding ferroelectrics

TL;DR

This paper explores how fluctuations in ferroelectric domain walls in bilayer van der Waals materials can induce attractive interactions between electrons, potentially leading to superconductivity, especially relevant in sliding ferroelectric systems.

Contribution

It introduces a novel mechanism where ferroelectric domain wall fluctuations mediate electron attraction, linking ferroelectricity and superconductivity in layered materials.

Findings

Domain walls are centers of strong electron attraction.

Ferroelectric fluctuations are driven by soft interlayer shear phonons.

Possible relevance to superconductivity observed in bilayer T$_d$-MoTe$_2$.

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.