Nonlinear phononic slidetronics

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.