Across-Layer Sliding Ferroelectricity in Graphene-Based Heterolayers: Asymmetry of Next Neighbor Interlayer Couplings

TL;DR

This paper introduces a model for across-layer sliding ferroelectricity in graphene-based heterolayers, explaining recent experimental observations and proposing potential applications in high-density data storage.

Contribution

It proposes a novel model based on asymmetry of next neighbor interlayer couplings to explain sliding ferroelectricity in symmetric 2D heterolayers.

Findings

Vertical polarizations can be switched via multilayer sliding.

Ferroelectric hysteresis in graphene bilayer intercalated with h-BN is explained.

Potential for high-density data storage using molecular layers.

Abstract

Although most two-dimensional (2D) materials are non-ferroelectric with highly symmetric lattices, symmetry breaking may take place in their bilayers upon certain stacking order, giving rise to so-called sliding ferroelectricity where the vertical polarizations can be electrically reversed via interlayer translation. However, it is not supposed to appear in systems like graphene bilayer with centro-symmetry at any stacking configuration, and the origin of the recently reported ferroelectricity in graphene bilayer intercalated between h-BN (Nature 2020, 588, 71) is still unclear. Here we propose a model of across-layer sliding ferroelectricity that arises from the asymmetry of next neighbor interlayer couplings. The vertical polarizations in intercalated centro-symmetric 2D materials like graphene bilayer can be switched via multilayer sliding, and the observed ferroelectric hysteresis can be clarified. Moreover, such ferroelectricity can exist in a series of other heterolayers with quasi-degenerate polar states, like graphene bilayer or trilayer on BN substrate, or even with a molecule layer on surface where each molecule can store 1 bit data independently, resolving the bottleneck issue of sliding ferroelectricity for high-density data storage.