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arXiv · 2604.00483

Revealing buried ferroelectric topologies by depth-resolved electron diffraction imaging

Ting-Ran Liu·Koushik Jagadish·Xiangwei Guo·Maya Ramesh·Peter Meisenheimer·Harish Kumarasubramanian·Sajid Husain·Ann V. Ngo·Amir Avishai·Jayakanth Ravichandran·Darrell G. Schlom·Ramamoorthy Ramesh·Yu-Tsun Shao
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Abstract

Nanoscale topological polar textures promise new functionalities for ferroelectric memories and logic, yet their three-dimensional structure and mesoscale organization remain experimentally inaccessible. Here we introduce depth-resolved electron diffraction imaging (DREDI), a fast, non-destructive, method that maps polarization with <50 nm lateral and <10 nm depth sensitivity within fraction of a second. Its high acquisition speed enables the first continuous polarization mapping across six orders of magnitude in length scale, from nanometers to millimeters. Using epitaxial BiFeO3 films, DREDI reveals a hidden depth evolution of polar textures: surface 71-degree stripes evolve into subsurface flux-closure vortices that bifurcate into three-fold vertices near the bottom interface. Cross-sectional multi-slice electron ptychography and phase-field modeling confirm these buried configurations and attribute them to strain heterogeneity and ferroelastic twinning in the SrRuO3 electrode. Large-area analysis further shows that vertex-like frustration forms a mesoscale percolating network above a critical length scale of 4 um. DREDI enables real-time, volumetric studies of buried topological textures in ferroic nanomaterials.

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Ting-Ran Liu, Koushik Jagadish, Xiangwei Guo, Maya Ramesh, Peter Meisenheimer, Harish Kumarasubramanian, Sajid Husain, Ann V. Ngo, Amir Avishai, Jayakanth Ravichandran, Darrell G. Schlom, Ramamoorthy Ramesh, Yu-Tsun Shao. 2026-04-01. Revealing buried ferroelectric topologies by depth-resolved electron diffraction imaging. https://arxiv.org/abs/2604.00483

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