High-Resolution Field Mapping using Electron Ptychography

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Direct visualisation of atomic structures and ferroic orderings in materials at the atomically thin limit is exciting not only from a fundamental physics perspective but is also critical for the characteristics of ferroelectric and ferromagnetic materials used in applications that include information storage and logic technologies. With ultrafast direct detectors, a new emerging high-resolution phase imaging technique, so-called ptychography has attracted considerable interest from both X-ray and electron communities for its potential applications in super-resolution imaging. Ptychography is a phase recovery method based on scanning in-line holography, as originally proposed by Hoppe. This approach uses a radiation source to illuminate a sample and records a series of diffraction patterns as a function of the illumination position to recover the sample exit plane wavefunction using iterative algorithms. Electron ptychography can potentially enable high-sensitivity observations of the ferroic-orderings within functional materials (such as 2D ferroic thin films) at unprecedentedly high resolution and sensitivity at a low temperature. In this research project, we will develop a novel ordering field imaging using electron ptychography together with "big data" processing methods and exploit opportunities by accelerating its application in functional materials. The quantitative imaging of the magnetization configurations will be extracted by comparison with detailed image simulations. Combined with tomographic methods, the electromagnetic field mapping will be potentially extended into three-dimensional field mapping inside nanostructured materials. The success of this project can also lead to exciting opportunities in next-generation nanoscale devices.