Rafal E. Dunin-Borkowski: Model-based characterisation of magnetic moments and charge densities in the transmission electron microscope
YUCOMAT & WRTCS 2022
YUCOMAT & WRTCS 2022
Herceg Novi, Montenegro, 2022
YUCOMAT & WRTCS 2022
Openning
YUCOMAT & WRTCS 2022
Ana Senos lecture
YUCOMAT & WRTCS 2022
Hamish L. Fraser lecture
YUCOMAT & WRTCS 2022
Poster Session
YUCOMAT & WRTCS 2022
Competition : : Best Poster Presentation
YUCOMAT & WRTCS 2022
Prof Uskokovic Welcome speech
YUCOMAT & WRTCS 2022
Herceg Novi, Montenegro, 2022
YUCOMAT & WRTCS 2022
Herceg Novi, Montenegro, 2022
YUCOMAT & WRTCS 2022
Board members
YUCOMAT & WRTCS 2022
Herceg Novi, Montenegro, 2022
YUCOMAT & WRTCS 2022
Audience
YUCOMAT & WRTCS 2022
Discussion
YUCOMAT & WRTCS 2022
Boat Trip
YUCOMAT & WRTCS 2022
Poster Session
YUCOMAT & WRTCS 2022
Vladimir Torchilin lecture
YUCOMAT & WRTCS 2022
Discussion
YUCOMAT & WRTCS 2022
Darya Farrokhnemoun
YUCOMAT & WRTCS 2022
MRS Serbia
YUCOMAT & WRTCS 2022
Discussion
YUCOMAT & WRTCS 2022
Herceg Novi, Montenegro
YUCOMAT & WRTCS 2022
Desk
YUCOMAT & WRTCS 2022
Dušan Tripković
YUCOMAT & WRTCS 2022
Herceg Novi, Montenegro
YUCOMAT & WRTCS 2022
Boat Trip
YUCOMAT & WRTCS 2022
Audience
YUCOMAT & WRTCS 2022
Yury Gogotsi lecture
YUCOMAT & WRTCS 2022
IISS

Rafal E. Dunin-Borkowski, Jan Caron, Patrick Diehle, Fengshan Zheng, Vadim Migunov and András Kovács

 

Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germanys

 

Off-axis electron holography is a powerful technique, which can be used to record the phase shift of an electron wave that has passed through an electron-transparent specimen in a transmission electron microscope. The phase shift is sensitive to local variations in electromagnetic potential, which are in turn dependent on nanoscale properties of a specimen of interest, such as magnetization or charge density.

We have developed a model-based iterative reconstruction technique, which can be used to retrieve the projected in-plane magnetization distribution from the magnetic contribution to a recorded phase image, or alternatively the three-dimensional magnetization distribution from a set of at least two tilt series of magnetic phase images [1]. The technique is based on the optimized implementation of a forward model, which maps a given magnetization distribution onto one or more phase images. The ill-posed problem is tackled by first replacing the original problem by a least squares minimization, which is augmented by regularization techniques to find a unique solution for the reconstructed magnetization distribution. We are also using the same model-based approach for reconstructing the projected or three-dimensional charge density distributions inside specimens from phase images. Just as for reconstructing magnetic moments, this approach allows the incorporation of a priori information, such as the shape of the object (i.e.,  the region in which charge can be located), as well as the use of a confidence mask to exclude regions containing artefacts from the analysis. Examples will be presented from the characterisation of magnetic moments in nanoscale grains and charge density distributions in electrically biased needle-shaped specimens [2].

 

[1] J. Caron, Model-Based Reconstruction of Magnetisation Distributions in Nanostructures from Electron Optical Phase Images, Ph.D. thesis, RWTH Aachen University, 2017. http://juser.fz-juelich.de/record/851773.

[2] The authors thank M Beleggia, G Pozzi, Z-A Li, J Ungermann, M Riese and M Farle for contributions to this work.

Plenary lectures - YUCOMAT 2019

member since 2008