TopoTEM: A Python Package for Quantifying and Visualizing Scanning Transmission Electron Microscopy Data of Polar Topologies

The exotic internal structure of polar topologies in multi-ferroic materials offers a rich landscape for materials science research. As the spatial scale of these entities are often sub-atomic in nature, aberration corrected transmission electron microscopy (TEM) is the ideal characterisation technique. Software to quantify and visualise the slight shifts in atomic placement within unit cells is of paramount importance due to the now routine acquisition of images at such resolution. In the previous ~decade since the commercialisation of aberration corrected TEM, many research groups have written their own code to visualise these polar entities. More recently, open access Python packages have been developed for the purpose of TEM atomic position quantification. Building on these packages, we introduce the TEMUL Toolkit: a Python package for analysis and visualisation of atomic resolution images. Here, we focus specifically on the TopoTEM module of the toolkit where we show an easy to follow, streamlined version of calculating the atomic displacements relative to the surrounding lattice and thus polarisation plotting. We hope this toolkit will benefit the rapidly expanding field of topology based nano-electronic and quantum materials research, and we invite the electron microscopy community to contribute to this open access project.
22 pages, 9 figures