Direct observation of electric and magnetic fields of functional materials

• Published in: Materials science & engineering. R, Reports : a review journal Vol. 142; p. 100564
• Main Authors: Shindo, Daisuke, Akase, Zentaro
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.10.2020; Elsevier BV
• Subjects: Charging effect; Collective motion of electrons; Composite materials; Disturbance-free observation; Electric currents; Electric fields; Electromagnetic field; Electromagnetic fields; Electromagnetism; Electron holography; Electron spin; Functional materials; Holography; In situ experiment; Insulators; Magnetic fields; Magnetic materials; Magnetization; Polarization (spin alignment); Stationary orbits; Collective motion of electrons; In situ experiment; Magnetization; Electromagnetic field; Charging effect; Disturbance-free observation; Electron holography
• ISSN: 0927-796X; 1879-212X
• DOI: 10.1016/j.mser.2020.100564

Electron holography is a useful technique to directly visualize the electromagnetic fields in and around various functional materials at the nanometer scale. The precision and resolution of this technique have been drastically improved by using various specialized instruments. From in situ experiments applying electric current and voltage and using these specialized instruments, conductivity changes in composite materials can be understood through their microstructure changes and electric field variations. On the other hand, the magnetization processes of various functional magnetic materials can also be clarified by applying a magnetic field and changing the temperature. As an extension of electron holographic techniques, the stationary orbits and collective motions of electrons around various charged insulators can be directly observed by detecting the electric field fluctuation due to these motions. Furthermore, by applying an external magnetic field to the electrons around charged insulators, the electron spin polarization can be observed. Thus, by combining the electron behaviors and electromagnetic fields of advanced functional materials under the application of electric current and external magnetic fields, we expect the development of new features in sensing techniques for clarifying the interactions between electrons and material surfaces. These studies offer a promising contribution of novel approaches for both development and characterization of advanced functional materials and devices based on them.