Polarization Topology at the Nominally Charged Domain Walls in Uniaxial Ferroelectrics
Polarization Topology at the Nominally Charged Domain Walls in Uniaxial Ferroelectrics
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DOI：
10.1002/adma.202203028
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发表时间：
2022-10-07
影响因子：
29.4
通讯作者：
Luk'yanchuk, Igor
中科院分区：
文献类型：
--
作者：
Tikhonov, Yurii;Maguire, Jesi R.;Luk'yanchuk, Igor
铁电畴壁为新材料物理学提供了一个肥沃的环境。如果出现极化不连续性，它可以驱动电子载流子的重新分布和能带结构的变化，这通常会导致出现2D导电性。如果这种不连续性是不能容忍的，那么它的改善通常涉及到复杂的拓扑模式的形成，如通量封闭域，偶极涡，skyrmions，merons或Hopfions。这种模式的发展所需的自由度，其中偶极旋转是一个标志，很容易在多轴铁电体中找到。在单轴铁电体中，只有两个相反的极性取向是可能的，它已被假定为不连续性是不可避免的，当极化的反平行分量满足。这种看法已经证实了在系统中，如六方锰氧化物和锂的碳酸盐的带电导电畴壁的外观。在这里，实验和理论研究铅锗酸盐（Pb5Ge3O11）揭示，极性不连续性可以避免在头对头和尾对尾畴壁相互畴分支沿着两个不同的轴，创建一个特征的鞍点畴壁形态和相关的新的偶极拓扑结构，消除了需要屏蔽电荷积累和相关的导电性增强。
Ferroelectric domain walls provide a fertile environment for novel materials physics. If a polarization discontinuity arises, it can drive a redistribution of electronic carriers and changes in band structure, which often result in emergent 2D conductivity. If such a discontinuity is not tolerated, then its amelioration usually involves the formation of complex topological patterns, such as flux-closure domains, dipolar vortices, skyrmions, merons, or Hopfions. The degrees of freedom required for the development of such patterns, in which dipolar rotation is a hallmark, are readily found in multiaxial ferroelectrics. In uniaxial ferroelectrics, where only two opposite polar orientations are possible, it has been assumed that discontinuities are unavoidable when antiparallel components of polarization meet. This perception has been borne out by the appearance of charged conducting domain walls in systems such as hexagonal manganites and lithium niobate. Here, experimental and theoretical investigations on lead germanate (Pb5Ge3O11) reveal that polar discontinuities can be obviated at head-to-head and tail-to-tail domain walls by mutual domain bifurcation along two different axes, creating a characteristic saddle-point domain wall morphology and associated novel dipolar topology, removing the need for screening charge accumulation and associated conductivity enhancement.