Department of Materials Science and Engineering, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Department of Materials Science and Engineering, University of California , Berkeley, California 94720, United States.
Nano Lett. 2017 Apr 12;17(4):2246-2252. doi: 10.1021/acs.nanolett.6b04875. Epub 2017 Mar 8.
A novel mesoscale state comprising of an ordered polar vortex lattice has been demonstrated in ferroelectric superlattices of PbTiO/SrTiO. Here, we employ phase-field simulations, analytical theory, and experimental observations to evaluate thermodynamic conditions and geometric length scales that are critical for the formation of such exotic vortex states. We show that the stability of these vortex lattices involves an intimate competition between long-range electrostatic, long-range elastic, and short-range polarization gradient-related interactions leading to both an upper and a lower bound to the length scale at which these states can be observed. We found that the critical length is related to the intrinsic domain wall width, which could serve as a simple intuitive design rule for the discovery of novel ultrafine topological structures in ferroic systems.
在 PbTiO/SrTiO 铁电超晶格中已经证明了一种由有序极涡旋晶格组成的新型介观状态。在这里，我们采用相场模拟、解析理论和实验观察来评估对于形成这种奇异涡旋状态至关重要的热力学条件和几何长度尺度。我们表明，这些涡旋晶格的稳定性涉及到长程静电、长程弹性和短程极化梯度相关相互作用之间的密切竞争，从而导致这些状态可以观察到的长度尺度存在上限和下限。我们发现，临界长度与本征畴壁宽度有关，这可以作为在铁电系统中发现新型超细拓扑结构的简单直观设计规则。
