Year: 2026
Type: preprint
Abstract: Polar topologies in complex oxides gives rise to a rich spectrum of emergent functionalities and are fundamentally governed by three-dimensional (3D) atomic structures. However, direct experimental determination of buried 3D polar configurations remains a longstanding challenge because conventional (scanning) transmission electron microscopy ((S)TEM) provides primarily projected structural information with limited depth sensitivity. Here, we combine depth-sectioning low-angle annular dark-field (LAADF) STEM, high-angle ADF (HAADF) STEM, and multislice electron ptychography (MEP) to directly visualize the depth-dependent atomic structure and polarization topology in a PTO/STO superlattice. Depth-sectioning STEM reveals pronounced focal-depth-dependent contrast variations and apparent splitting of Pb atomic columns, indicating significant structural heterogeneity along the beam direction. MEP reconstruction simultaneously resolves the Pb, Ti, and O sublattices with nanometer-scale depth resolution, enabling quantitative mapping of atomic displacements throughout the reconstructed volume. The resulting 3D atomic model reveals substantial depth-dependent displacements of Pb, Ti, and O atoms and a corresponding evolution of the polarization topology. Vortex-like polarization structures are observed near the specimen surfaces but become strongly suppressed within the interior, where distinct polarization configurations emerge. These findings show that polarization patterns observed in conventional projection images can arise from the superposition of multiple depth-dependent polar states and may obscure the underlying 3D polarization texture. Our findings establish a direct experimental link between local atomic displacements and depth-dependent polarization topology, opening new opportunities for investigating and engineering buried functional states in complex oxide nanostructures.
Source: arXiv (Cornell University)
Institutions: Institut Català de Nanociència i Nanotecnologia, Barcelona Institute of Science and Technology, Forschungszentrum Jülich, Ernst Ruska Centre, Centro Singular de Investigación en Química Biológica y Materiales Moleculares, University of Wisconsin–Madison, Beijing Institute of Technology, Chinese Academy of Sciences, Fujian Institute of Research on the Structure of Matter, Institució Catalana de Recerca i Estudis Avançats
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, U.S. Department of Energy, Gordon and Betty Moore Foundation, University of Wisconsin-Madison, Centres de Recerca de Catalunya, Institut Català de Nanociència i Nanotecnologia, European Commission, Deutscher Akademischer Austauschdienst, National Natural Science Foundation of China, Generalitat de Catalunya, Forschungszentrum Jülich, China Scholarship Council, Ministerio de Ciencia e Innovación, Xunta de Galicia, Office of Science, European Regional Development Fund, Agencia Estatal de Investigación, Office of Naval Research, Basic Energy Sciences
Awards: G1059279500, G1119546765, G1175115578, G1204740081, G1206670709, G120905174, G1272927172, G1301230144, G1303726027, G1370960138, G1401168639, G1458792852, Collaborative Research: DMREF: NSF-BSF: Moire-Engineered Oxide Membrane Heterostructures by Design, G1785621623, G1855990336, G1911915008, G1938383553, G200216835, G2064873908, G2138380992, G222768804, G2262748287, G2291644657, G2309174360, G2316327515, G24120701, GROWTH AND CHARACTERIZATION OF ATOMIC LAYER CONTROLLED MGB2 THIN FILMS, G2462415295, G252646220, G2601397997, G2660406951, G2745972340, G294895050, G2988934680, G3005324705, G300979063, GROWTH AND CHARACTERIZATION OF ATOMIC LAYER CONTROLLED MGB2 THIN FILMS, G3264770651, G3480869486, G348919436, G3518538256, G3546882995, G354764522, G357246561, G363809202, G3681454997, G3847472936, G387506447, G3876637791, G3956782466, G4042783231, G410571670, G4228227490, G425668148, G430777504, G4353487559, G4503428130, G451917667, G464105488, G4642345579, G478805231, G503941229, G5046955865, G5080475149, G5148776692, G5166420213, G5195188938, G523076202, G5241663416, G531036588, G5338730000, G5353516086, G5417250019, G5421974903, G5442265231, G5539308778, G5590387194, G5648016710, G5662792045, G5922099756, G5958277091, G5967599077, G5989518409, G6011688299, G6033112984, G6295457465, G6441290718, G6605876378, G6656126374, G6762955466, G67688110, G676985872, G677611228, G6818627905, G7016589888, G7084143925, G7420629364, G7434936867, G745419941, G7764612811, G787121397, G7953654833, G8006577219, G8207841777, G8345352404, Chang-Beom Eom Materials Synthesis Investigator, G8522095481, G8546142835, G8575141037, G8876996369, G8920660035, G8966434229, G99296377
OpenAlex ID: W7204500075
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