Liquid-crystal-like dynamic transition in ferroelectric/dielectric superlattices

Abstract

Nanostructured ferroelectrics display exotic multidomain configurations resulting from the electrostatic and elastic boundary conditions they are subject to. While the ferroelectric domains appear frozen in experimental images, atomistic second-principles studies suggest that they may become spontaneously mobile upon heating, with the polar order {\sl melting} in a liquid-like fashion. Here we run molecular dynamics simulations of model systems (PbTiO${}_3$/SrTiO${}_3$ superlattices) to study the unique features of this transformation. Most notably, we find that the multidomain state looses its translational and orientational orders at different temperatures, resembling the behavior of liquid crystals and yielding an intermediate hexatic-like phase. Our simulations reveal the mechanism responsible for the melting and allow us to characterize the stochastic dynamics in the hexatic-like phase: we find evidence that it is thermally activated, with domain reorientation rates that grow from tens of gigahertzs to terahertzs in a narrow temperature window.

7 pages, 4 figures

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Cited by in corpus (5)

• Dynamical manipulation of polar topologies from acoustic phonon pumping
• Topological phase transitions in perovskite superlattices driven by temperature, electric field, and doping
• Inhomogeneous Electric Fields for Precise Control and Displacement of Polar Textures
• Creating currents of electric bubbles
• Switchable Topological Polar Textures in Freestanding Ultrathin Ferroelectric Oxides