💫 PRL发表记录：铁电螺旋🧬

💫 PRL发表记录：铁电螺旋🧬 | First PRL Paper Accepted

旋转零能模式 —— 偶极螺旋中的偶极子可以自由旋转而不消耗能量，这是我在 PRL 工作中最激动人心的发现。对物理系学生而言，PRL 是顶刊的圆满；而 Editor’s Suggestion 的额外认可，更让这份圆满多了一抹金色。

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📄 论文信息

• 标题：Giant Piezoelectric Effects of Topological Structures in Stretched Ferroelectric Membranes
• 期刊：Physical Review Letters, 133, 046802 (2024) (🔖Editor’s Suggestion)
• DOI：10.1103/PhysRevLett.133.046802
• 发表日期：26 July 2024（Received 2 February 2024; accepted 18 June 2024）
• 关键发现：在拉伸的 PbTiO₃ 薄膜中发现了 偶极螺旋（dipole spiral） 结构，该结构具有 旋转零能模式（rotational zero-energy mode），使得偶极子可以集体、相干地自由旋转，并产生巨大的压电响应（>320 pC/N）。

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从第一性原理计算到深度势能分子动力学，从发现偶极螺旋到揭示其零能旋转模式，一言以蔽之，帅。PRL 的 acceptance 是对我们工作的最高认可，而 Editor’s Suggestion 更意味着编辑认为这项工作具有特别的重要性或广泛的兴趣。

感谢导师的指导与合作者的讨论，也感谢西湖大学提供的计算资源。

PHYSICAL REVIEW LETTERS 133, 046802

Editors' Suggestion

Giant Piezoelectric Effects of Topological Structures in Stretched Ferroelectric Membranes

Yihao Hu, Jiyuan Yang, and Shi Liu

Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University
Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, China

1. Introduction & Methodology

Freestanding ferroelectric oxide membranes emerge as a promising platform for exploring the interplay between topological polar ordering and dipolar interactions that are continuously tunable by strain.

Methodological Breakthrough: We combined density functional theory (DFT) and deep-learning-assisted molecular dynamics (DPMD) simulations.

This allows us to construct phase diagrams at finite temperatures, advancing beyond the single-domain assumption often used to reduce computational costs in traditional first-principles approaches.

2. Finite-Temperature Domain Evolution

DFT calculations indicate a tensile-strain-driven morphotropic phase boundary (MPB) with competing monoclinic phases. However, our DPMD simulations demonstrate that these features behave differently in thermally active environments.

• The flat potential energy landscape results in diverse domain structures at room temperatures.
• These structures feature continuous distributions of dipole orientations and mobile domain walls.

3. Dynamic Mechanism of Enhanced d₃₃

Detailed analysis of dynamic structures reveals the true origin of the enhanced piezoelectric response observed in stretched PbTiO₃ membranes.

The enhancement results from collective and coordinated small-angle rotations of dipoles at domain walls.

This dynamic coordination is distinct from the conventional polarization rotation mechanism and adaptive phase theory inferred from static structures. Stretching the membrane activates spontaneous and stochastic oscillations of 90° domain walls, pushing d₃₃ to ~250 pC/N (3 times that of a single domain).

4. Discovery: The Dipole Spiral

We identify a novel ferroelectric topological structure, termed the "dipole spiral".

• Characterized by canted dipoles that progressively rotate around the out-of-plane direction.
• The dynamic structure is highly vibrant, where dipoles rotate collectively, coherently, and stochastically.

5. Giant Piezoelectricity & Zero-Energy Mode

The collective response of the dipole spiral to external stimuli is achieved via small-angle rotations.

Giant Intrinsic Piezoelectric Response

> 320 pC/N

Crucially, this helical structure possesses a rotational zero-energy mode. Strongly correlated dipoles can rotate freely without energy cost.

6. Conclusion & Outlook

Our findings establish that dynamic structure dictates functional properties.

• We propose a feasible experimental approach to realize the dipole spiral using all-ferroelectric superlattices composed of alternating layers of PbTiO₃ and Pb_0.5Sr_0.5TiO₃.
• This structure unlocks new possibilities for exploring chiral phonon dynamics and dipolar Dzyaloshinskii-Moriya-like interactions.

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📌 下一步：（靠师弟）继续探索 chiral phonon dynamics 与 dipolar Dzyaloshinskii-Moriya-like interaction。