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Achievement
Achievement
Cryogenic four-dimensional scanning transmission electron microscopy (4D-STEM) imaging is a useful technique for studying quantum materials and their interfaces by simultaneously probing charge, lattice, spin, and chemistry on the atomic scale with the sample held at temperatures ranging from room to cryogenic. However, its applications are currently limited by the instabilities of cryo-stages and electronics. To overcome this challenge, we develop an algorithm to effectively correct the complex distortions present in atomic resolution cryogenic 4D-STEM data sets. This method uses nonrigid registration to identify localized distortions in a 4D-STEM and relate them to an undistorted experimental STEM image, followed by a series of affine transformations for distortion corrections. This method allows a minimum loss of information in both reciprocal and real spaces, enabling the reconstruction of sample information from 4D- STEM data sets. This method is computationally cheap, fast, and applicable for on-the-fly data analysis in future in situ cryogenic 4D-STEM experiments.
Stages of the 4DSTEM distortion correction algorithm. (a,b) The atomic columns in the STEM (a) and 4DSTEM (b) images are located and sorted so that a one-to-1 feature map can be acquired. (c) A mesh of triangles is created to localize any distortions. (d) The corrected 4DSTEM BF image demonstrates nonuniform sampling. (e) The weighted radial average algorithm returns the data set to a uniform sampling rate. (f) The final corrected image is constrained within the bounds of the recognized features and is visibly less distorted. Contrast is inverted to match the ADF STEM image.
Publication
Publication
J. Smith, Z. Huang, W. Gao, G. Zhang, M. Chi, Atomic resolution cryogenic 4D-STEM imaging robust distortion correction, ACS Nano, Vol 17, pp. 11327-11334, 2023. (DOI: 10.1021/acsnano.2c12777).
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