Stacking-engineered ferroelectricity in bilayer boron nitride

Two-dimensional (2D) ferroelectrics with robust polarization down to atomic thicknesses provide building blocks for functional heterostructures. Experimental realization remains challenging because of the requirement of a layered polar crystal. Here, we demonstrate a rational design approach to engineering 2D ferroelectrics from a nonferroelectric parent compound by using van der Waals assembly. Parallel-stacked bilayer boron nitride exhibits out-of-plane electric polarization that reverses depending on the stacking order. The polarization switching is probed through the resistance of an adjacently stacked graphene sheet. Twisting the boron nitride sheets by a small angle changes the dynamics of switching because of the formation of moire ferroelectricity with staggered polarization. The ferroelectricity persists to room temperature while keeping the high mobility of graphene, paving the way for potential ultrathin nonvolatile memory applications.

Automated summary

In this research, ferroelectricity is achieved in two-dimensional boron nitride through van der Waals assembly, demonstrating the phenomenon that polarization can be changed by twisting the angle. This discovery paves the way for potential applications in ultrathin nonvolatile memory, while maintaining the high mobility of graphene.