  To enhance the efficiency of next-generation ferroelectric (FE) electronic
devices, new techniques for controlling ferroelectric polarization switching
are required. While most prior studies have attempted to induce polarization
switching via the excitation of phonons, these experimental techniques required
intricate and expensive terahertz sources and have not been completely
successful. Here, we propose a new mechanism for rapidly and efficiently
switching the FE polarization via laser-tuning of the underlying dynamical
potential energy surface. Using time-dependent density functional calculations,
we observe an ultrafast switching of the FE polarization in BaTiO3 within 200
fs. A laser pulse can induce a charge density redistribution that reduces the
original FE charge order. This excitation results in both desirable and highly
directional ionic forces that are always opposite to the original FE
displacements. Our new mechanism enables the reversible switching of the FE
polarization with optical pulses that can be produced from existing 800 nm
experimental laser sources.
