Continuously Tuning Negative Capacitance via Field-Driven Polar Skyrmions in Ferroelectric Trilayer Wrinkled Films.

Polar topological structures have emerged as a frontier in research due to their significant potential in nanoscale electronic devices. The periodic and ordered arrangement, as well as the dynamic control mechanisms, are essential for their practical applications. Here, we present theoretical phase-field simulations that reveal the periodic and ordered arrangement of skyrmions and in-plane vortices within (SrTiO)/(PbTiO)/(SrTiO) checkerboard-patterned wrinkled trilayer films. Each skyrmion wall exhibits a stable negative capacitance that significantly enhances the effective dielectric permittivity. The negative capacitance results from polarization reversal at the domain walls under small electric field perturbations, closely linked to the depolarization field. The direction of the external electric field can determine the location of the negative capacitance region, which is not strictly confined to the original domain walls but exhibits a shift. These topologically protected structures undergo reversible phase transitions from skyrmion and vortex states to a uniform ferroelectric state under the influence of electric fields and strain, accompanied by highly tunable permittivity. This interplay between topological structures and dielectric characteristics in flexible ferroelectric films offers the opportunity to simultaneously manipulate both topological and dielectric properties through external stimuli, thereby broadening the design possibilities for flexible electronic materials.