Topological Phase Transitions, Phase Diagrams, and Dielectric Properties of Pb(Zr0.7Ti0.3)O3-Based Superlattices

Abstract

Ferroelectric/paraelectric superlattices, created through the periodic stacking of their constituent materials, exhibit intricate phase diagrams that reveal a variety of polar topologies and properties not found in any of the individual components. In this study, the phase-field simulations are utilized to systematically calculate the phase diagrams of Zr-rich Pb(Zr, Ti)O₃/SrTiO₃ superlattices with varying periodicity, strain, and temperature. A rhombohedral-type labyrinth domain is observed, which is oriented along the [110] direction under relatively low compressive strain. Meanwhile, higher compressive strains lead to the formation of polar skyrmions with shorter periodicities. Notably, a high dielectric permittivity of 1700 is found at room temperature for the polar skyrmion phase with a periodicity of 6 when grown on a DyScO₃ substrate, which is double the value for the skyrmion phase in a PbTiO₃/SrTiO₃ superlattice. Moreover, a phase transition from skyrmion, vortex/labyrinth states to a cubic phase at elevated temperatures is discovered, accompanied by a significant reduction in dielectric responses. It is hoped that the work will inspire further exploration into the design of intriguing polar topologies with superior properties.