# Parallel mode differential phase contrast in transmission electron microscopy

, , and Togawa, Y. (2021) Parallel mode differential phase contrast in transmission electron microscopy. arXiv, (Unpublished)

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Publisher's URL: https://arxiv.org/abs/2104.06769

## Abstract

The ability to map electro- and magneto-static fields in transmission electron microscopy (TEM) has been critical to fundamental research into materials and their applications. Here, we outline the parallel mode of differential phase contrast (TEM-DPC), which uses real-space distortion of Fresnel images to quantify the phase gradient of samples with some degree of structural contrast. Through numerical simulations, we compare the technique to the widely used transport-of-intensity (TIE) method for phase recovery, and discuss the relative advantages and limitations of each. The TEM-DPC technique is particularly suitable for \textit{in-situ} studies of samples with significant structural contrast and, as such, complements the TIE method since this property usually hinders the former, but is an essential feature that enables the latter. We use the TEM-DPC technique on cryo-TEM images of a thin lamella of a low temperature two-dimensional (2-D) ferromagnetic material, K$_2$CuF$_4$. By tracking the induction as the sample is driven through a phase transiti on by heating, we extract estimates for the critical temperature and critical exponent of the ordering parameter that are consistent with the 2-D XY class.

Item Type: Articles Unpublished No Togawa, Dr Yoshihiko and Macauley, Mr Gavin and Paterson, Dr Gary and McVitie, Professor Stephen College of Science and Engineering > School of Physics and Astronomy arXiv

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
190883Consortium for advanced materials based on spin chiralityStephen McVitieEngineering and Physical Sciences Research Council (EPSRC)EP/M024423/1P&S - Physics & Astronomy