90th CEMS Colloquium

Title

Electron Holographic Visualization of Electromagnetic Fields and Electron Behavior

Abstract

Recent progress in electron holography is reviewed [1]. Thanks to drastic improvements of precisions and resolutions of special observation instruments [2], it has become possible to quantitatively analyze both electric [3] and magnetic [4] fields in advanced materials at a nanometer scale. Distributions and orbits of emitted secondary electrons around charged insulator surfaces have been observed by detecting electric field variations due to electron motions [1]. By applying magnetic fields to these secondary electrons, the magnetic fields created by electron spin polarizations were also observed (Fig. 1) and analyzed by using simulation. These findings are expected to lead to developments of new technologies for manipulating electrons and for visualizing electron interactions with advanced materials.

Fig. 1 ：In situ observation of electron spin polarization around charged mica surface

[1] D. Shindo and Z. Akase, “Direct observation of electric and magnetic fields of functional materials”, Materials Science and Engineering: R., 142, 100564-1-54 (2020).
[2] D. Shindo et al., “Advanced electron holography applied to electromagnetic field study in materials science”,  Advanced Materials, 29, 1602216-1-15 (2017).
[3] M. Nakamura et al., “Spontaneous polarization and bulk photovoltaic effect driven by polar discontinuity in LaFeO₃/SrTiO₃ heterojunctions”, Physical Review Letters, 116(15), 156801-1-5 (2016).
[4] H.S. Park et al.,“Observation of the magnetic flux and three-dimensional structure of skyrmion lattices by electron holography”, Nature Nanotechnology, 9, 337-342(2014).