Coherent translational motion of ferroelectric vortex pairs modulated by electrostatic screening

Controlling the motion of nanoscale topological structures in ferroelectric materials offers a pathway toward non-volatile, high-density, and energy-efficient information storage technologies. Here, two-dimensional phase-field simulations are employed to explore the translational dynamics of ferroelectric vortex pairs driven by a localized, moving electric field in epitaxial PbTiO3 thin films. We identify a finite range of electrostatic screening within which vortex pairs exhibit coherent co-propagation, functioning as mechanically and electrostatically bound states with preserved internal structure during transport. We clarify the physical origin of this window via a force-balance picture between a depolarization-field driving force and an elastic confining force, and we introduce a restoring potential that stabilizes a fixed inter-vortex spacing during motion. Outside this range, mobility is suppressed: insufficient screening stabilizes extended vortex arrays, while excessive screening leads to independent wall motion and defect annihilation. Temperature and epitaxial misfit strain act as secondary but significant parameters enabling gradual or nonlinear tuning of the inter-vortex spacing without compromising stability. This work demonstrates the feasibility of the controlled transport of ferroelectric vortex pairs, maps the multi-parameter phase space governing their stability and motion, and elucidates the interplay among electrostatic coupling, elastic confinement, and thermal effects. The findings provide design guidelines for racetrack-type ferroelectric devices, in which mobile topological textures can be precisely positioned, manipulated, and integrated into next-generation memory and logic architectures.