含羞草视频 this event

In order to better understand localised magnetic behaviour of individual nanostructures, it is necessary to employ characterisation techniques that allow direct measurements of magnetic induction at high spatial resolution. Lorentz microscopy encompasses several techniques within the transmission electron microscope (TEM) that allow imaging of nano-scale magnetism approaching ~1 nm spatial resolution, including Fresnel imaging, electron holography and differential phase contrast (DPC) imaging. Further, combining in situ TEM experiments with these techniques allows for visualising dynamic magnetic events whilst under the influence of external stimuli; e.g. applying biasing or magnetic fields, controlled atmospheres, temperature, etc. In this context, several examples of the combining in situ TEM with magnetic imaging TEM methods will be presented. 1)Through combining electron holography with environmental TEM and in situ heating, the effects of oxidation and temperature on the magnetic behaviour of vortex-state Fe3O4 NPs are visualised successfully. 2) Fresnel, conventional and pixelated DPC imaging is combined with in situ heating and biasing to image directly the magnetostructural transition and domain wall motion in planar and cross-sectional FeRh films. 3) Electron holography and conventional / pixelated DPC imaging is combined with application of in situ magnetic fields to visualise switching between two stable degenerate target Skyrmion ground states (FeGe nanodisk) and Skyrmion symmetry lowering distortions (FeGe wedge), respectively.