Stacking ferroelectricity (SFE) has been discovered in a wide range of van der Waals materials and holds promise for applications, including photovoltaics and high-density memory devices. We show that the microscopic origin of out-of-plane stacking ferroelectric polarization can be generally understood as a consequence of a nontrivial Berry phase borne out of an effective Su-Schrieffer-Heeger model description with broken sublattice symmetry, thus elucidating the quantum-geometric origin of polarization in the extremely nonperiodic bilayer limit. Our theory applies to known stacking ferroelectrics such as bilayer transition-metal dichalcogenides in $3R$ and $T_{\mathrm{d}}$ phases, as well as general $AB$-stacked honeycomb bilayers with staggered sublattice potential. Our explanatory and self-consistent framework based on the quantum-geometric perspective establishes quantitative understanding of out-of-plane SFE materials beyond symmetry principles.

中文翻译：

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面外堆叠铁电性的量子几何起源

堆叠铁电性 (SFE) 已在多种范德华材料中被发现，并有望在光伏和高密度存储设备等领域得到广泛应用。我们表明，面外堆叠铁电极化的微观起源通常可以理解为非平凡 Berry 相的结果，该 Berry 相源自有效的 Su-Schrieffer-Heeger 模型描述，具有破缺的亚晶格对称性，从而阐明了量子几何极端非周期性双层极限中的极化起源。我们的理论适用于已知的堆叠铁电体，例如双层过渡金属二硫属化物$3右$和${\mathrm{时间}}_{\mathrm{d}}$阶段以及一般$A乙$-具有交错亚晶格势的堆叠蜂窝状双层。我们基于量子几何视角的解释性和自洽框架建立了对超越对称原理的面外超临界流体材料的定量理解。