Outline
For observing and analyzing emergent matter phenomena, we use advanced electron microscopy, especially electron holography. Electron holography is a leading-edge observation technology that utilizes interference effects of electron waves and visualizes electromagnetic fields on the nanometer scale. By developing multifunctional transmission electron microscope-specimen holders equipped with plural probes, changes in the electromagnetic fields in and around specimens under applied voltages and magnetic fields are quantitatively investigated. By improving resolutions and precisions of these observation technologies, we can extensively study mechanisms of emergent matter phenomena in newly designed specimens for investigating many-body systems with multiple degrees of freedom.
Research Fields
Materials Science, Physics, Engineering
Keywords
Imaging
Electron microscopy
Lorentz microscopy
Flux quantum
Electron holography
Nanomagnetism
Results
In situ observation of accumulation and collective motion of electrons
Comprehensive understanding of electromagnetic fields requires their visualization both inside and outside of materials. Since electromagnetic fields originate from various motions of electrons, comprehensive study of motions of electrons is of vital importance as well as of significant interest for understanding various emergent phenomena. The purpose of this study is to extend electron holography technology to visualize motions of electrons. By detecting electric field variations through amplitude reconstruction processes for holograms, we have succeeded in visualizing collective motions of electrons around various insulating materials. The lower right figures below show one of our experimental results of visualization of the collective motions of electrons around microfibrils of sciatic nerve tissue. In these reconstructed amplitude images, the bright yellow regions indicate the area where electric field fluctuates due to the motions of electrons. At the initial state (top figure),the electric field variations are not prominent. When the electron irradiation continues, however, bright yellow regions appear and the position of the regions changes gradually between the two branches as indicated by black arrows in the lower figures. These results indicate that the collective motions of electrons can be detected through electric field variation and can be visualized through amplitude reconstruction process for holograms.
Reconstructed amplitude images around microfibrils of sciatic nerve tissue (green).The bright yellow regions indicate the area where electric field fluctuates due to motions of electrons.
Electrical pulses shift the boundaries between magnetic patterns
