425 research outputs found
Observation of thermally-induced magnetic relaxation in a magnetite grain using off-axis electron holography
A synthetic basalt comprising magnetic Fe3O4 grains (~ 50 nm to ~ 500 nm in diameter) is
investigated using a range of complementary nano-characterisation techniques. Off-axis electron
holography combined with in situ heating allowed for the visualisation of the thermally-induced
magnetic relaxation of an Fe3O4 grain (~ 300 nm) from an irregular domain state into a vortex state at
550˚C, just below its Curie temperature, with the magnetic intensity of the vortex increasing on cooling
Wigner Distribution Deconvolution Adaptation for Live Ptychography Reconstruction
We propose a modification of Wigner Distribution Deconvolution (WDD) to
support live processing ptychography. Live processing allows to reconstruct and
display the specimen transfer function gradually while diffraction patterns are
acquired. For this purpose we reformulate WDD and apply a dimensionality
reduction technique that reduces memory consumption and increases processing
speed. We show numerically that this approach maintains the reconstruction
quality of specimen transfer functions as well as reduces computational
complexity during acquisition processes. Although we only present the
reconstruction for Scanning Transmission Electron Microscopy (STEM) datasets,
in general, the live processing algorithm we present in this paper can be
applied to real-time ptychographic reconstruction for different fields of
application
Focused Electron-Beam Induced Deposition, In Situ TEM And Off-Axis Electron Holography Investigation of Bi-Magnetic Core-Shell Nanostructures
No abstract available
A single slice approach for simulating two-beam electron diffraction of nanocrystals
[EN] A simple computational method that can be used to simulate TEM image contrast of an electron beam diffracted
by a crystal under two-beam dynamical scattering conditions is presented. The approach based on slicing the
shape factor is valid for a general crystal morphology, with and without crystalline defects, avoids the column
approximation, and provides the complex exit wave at the focal and the image planes also under weak-beam
conditions. The approach is particularly efficient for large crystals and the 3D model required for the calculations
can be measured experimentally using electron tomography. The method is applied to show that the shape of a
diffracted spot can be affected by shifts, broadening and secondary maxima of appreciable intensity, even for a
perfect crystal. The methodology is extended for the case of electron precession diffraction, and to show how can
be used to improve nanometrology from diffraction patterns. The method is used also to perform simulations of
simple models of crystalline defects. The accuracy of the method is demonstrated through examples of experimental
and simulated dark-field images of MgO and ZrO2 nanocrystals and thin layers of CeO2
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