We develop a phase-field model for the simultaneous evolution dynamics of electronic carriers and ferroelectric domains. As an illustrative example, we simulate the transient response of the most common 90° twin domains in a PbTiO₃ crystal with electron-hole pairs excited by an ultrafast above-bandgap light pulse which demonstrates a two-stage carrier relaxation coupled with multi-component structural responses across ps-ns timescales. The theoretical framework for predicting and manipulating carrier-related ultrafast dynamics of ferroelectric domains is expected to stimulate future experiments on the rich coupled evolution dynamics of domains, domain walls, and electronic charge carriers. In collaboration with Argonne National Lab and UC Berkeley, we are currently applying this model to understand the influence of the light-excited electronic carriers on the formation of a mesoscale 3-dimensional supercrystal in ferroelectric heterostructures.

Figure. (a) Three types of common 90° twin domains in a PbTiO₃ crystal possessing different bound charge densities at equilibria. (b) Strain evolution of the three types of domains upon an above-bandgap excitation showing the domain and domain wall dynamics mediated by electronic charge carriers.