Magnetic Nanostructure Analysis Using Electron Holography: A Review of Recent Studies of Phase Separation and Planar Defects in Crystals

This article reviews recent electron holography (EH) studies that examined the relationship between complex crystallographic and magnetic microstructures in alloys and other compounds. Such studies have determined the magnetic flux distributions in the mixed-phase states of a hole-doped manganite exhibiting colossal magnetoresistance. Studies of interface magnetism using EH have also demonstrated the generation of antiphase boundaries (a type of planer defect) in which ferromagnetic spin order is developed, in contrast to observations of other ordered crystals. In addition, EH has been used to accurately determine the magnetic flux density in a narrow grain boundary produced in a sintered magnet and accordingly has provided useful information related to the improvement of coercivity.