Nonlinear phononic slidetronics

TL;DR

This paper demonstrates a novel method for switching ferroelectricity in bilayer hexagonal boron nitride using nonlinear phonon excitation, enabling ultrafast control of stacking order in van der Waals materials.

Contribution

It introduces a new approach to control ferroelectric states via nonlinear phononics, overcoming limitations of traditional excitation methods.

Findings

High-frequency intralayer phonons can tilt the interlayer potential energy landscape.

Conventional excitation methods like infrared absorption are insufficient for switching.

Nonlinear phonon excitation enables efficient and ultrafast stacking order control.

Abstract

Van der Waals ferroelectrics are conventionally switched by sliding the different layers between stacking orders with opposing electric polarizations. Ultrashort laser pulses have been proposed to launch shear modes and induce switching, with often unfeasible large pulse energies however. Here, we demonstrate switching of ferroelectricity in bilayer hexagonal boron nitride through nonlinearly excited phonons. We show that the efficiencies of conventional coherent phonon excitation mechanisms, including infrared absorption and Raman scattering techniques, are too low to overcome the energy barrier separating the two ferroelectric states. We demonstrate instead that excitation of high-frequency intralayer modes leads to a tilting of the interlayer potential-energy landscape that enables changing the stacking order. Our results provide an avenue towards efficient phononic slidetronics, enabling ultrafast control of the stacking order in van der Waals materials.