Keithley Award: Turning Diffraction into Measurement: Quantitative 3D Atomic and Vector-Field Metrology
ORAL · Invited
Abstract
Coherent electron and X-ray diffraction combined with computational reconstruction has evolved from an imaging technique into a quantitative metrology framework that unifies key principles of microscopy and crystallography, enabling the determination of three-dimensional structure and fields across length scales. In this talk, I will highlight two measurement frontiers that arise from this diffraction-to-metrology transformation. First, I will present ptychographic atomic electron tomography (pAET), which achieves the first 3D localization of individual light atoms with picometer-level precision. Using twisted bilayer graphene as a model system, pAET determines the 3D coordinates of 6,649 carbon atoms with an overall precision of ~11 pm, quantifies moiré-driven corrugation and interlayer spacing, and uncovers chiral lattice distortions with meron-, anti-meron-, and anti-skyrmion-like textures. Incorporating the experimentally measured atomic coordinates into DFT calculations reveals an asymmetric ~22 meV bandgap absent in relaxed models, demonstrating that picometer-scale structural metrology directly alters the inferred electronic landscape. Second, I will describe soft-X-ray vector ptycho-tomography, which determines the 3D magnetization vector field of a ferromagnetic meta-lattice with 10 nm spatial resolution, sufficient to resolve features at the magnetic exchange length. This enables quantitative identification of 138 topological magnetic monopoles and anti-monopoles and measurement of their interaction statistics, revealing separation distances of 18.3 ± 1.6 nm for TMM–anti-TMM pairs and larger separations for like-charged pairs. Together, these advances establish coherent diffraction with algorithmic reconstruction as a unified and quantitative platform for 3D atomic and 3D vector-field metrology, opening new opportunities for addressing fundamental questions in condensed matter physics, quantum materials, and materials science broadly.
*I acknowledge support from STROBE: a National Science Foundation Science and Technology Center under award DMR 1548924; the US Department of Energy, Office of Science, Basic Energy Sciences, Division of Materials Sciences and Engineering under award DE-SC0010378; the US Air Force Office Multidisciplinary University Research Initiative (MURI) program under award FA9550-23-1-0281; and the US Army Research Office MURI program under award. W911NF-18-1-0431.
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Publication:1. J. Miao, "Computational microscopy with coherent diffractive imaging and ptychography", Nature 637, 281–295 (2025). 2. N. Y. Kim, H. Zhong, J. Zhang, C. M. O'Leary, Y. Liao, J. Zou, H. Sha, M. Pham, W. Li, Y. Yuan, J.-H. Park, D. Kim, H. Jiang, J. Kong, M. Chi, and J. Miao, "Three-dimensional imaging of individual carbon atoms", arXiv:2504.08228, submitted. 3. A. Rana, C.-T. Liao, E. Iacocca, J. Zou, M. Pham, X. Lu, E.-E. Cating Subramanian, Y. H. Lo, S. A. Ryan, C. S. Bevis, R. M. Karl Jr, A. J. Glaid, J. Rable, P. Mahale, J. Hirst, T. Ostler, W. Liu, C. M. O'Leary, Y.-S. Yu, K. Bustillo, H. Ohldag, D. A. Shapiro, S. Yazdi, T. E. Mallouk, S. J. Osher, H. C. Kapteyn, V. H. Crespi, J. V. Badding, Y. Tserkovnyak, M. M. Murnane and J. Miao, "Three-dimensional topological magnetic monopoles and their interactions in a ferromagnetic meta-lattice", Nat. Nanotechnol. 18, 227–232 (2023).
