Nanosecond electric pulse-induced local domain switching in BaTiO₃ nano-thin films

Domain switching between bistable remanent polarization states in ferroelectric thin film capacitors constitutes the fundamental storage mechanism of ferroelectric random access memory. Systematic understanding of the dynamics of local domain evolution under nanosecond electric pulses remains limited owing to the experimental difficulty of resolving local domain behavior with adequate spatiotemporal resolution. In this work, the phase-field approach governed by a second-order time-dependent Ginzburg-Landau equation is used to examine the dependence of domain switching behavior of varying domain region sizes on pulse durations and amplitudes. The characteristic response of domain switching in epitaxial single-crystalline BaTiO₃ thin films with a thickness of 20 nm is taken to be the equilibrium length of the switched domain and the time-dependent fraction of switched domains. Electric pulses with durations of 1–20 ns and amplitudes of 1–10 V are applied through the top and bottom electrodes to domains of different sizes. The results show that for larger domain regions of 50 and 100 nm, increasing pulse duration produces a logarithmic growth of the switched domain length. For a domain size of 20 nm, however, the voltage rising rate exerts stronger control over the switched domain length than the total pulse duration. The rapid voltage rise further induces inertial effects, leading to oscillations during polarization switching and transient domain instabilities. For pulse amplitudes, the switched domain length rises rapidly up to 1.7 V and then shows a slight reduction between 1.7 and 3 V due to inertial reversal dynamics. At higher voltages (>3 V), domain growth proceeds more rapidly, while the fraction of switched domains exhibits pronounced oscillations shortly after the pulse rise. This behavior can be attributed to the field-induced modification of the free-energy landscape, which evolves from a double-well to a single-well potential at high amplitudes.