Maze and bubble domains in magnetic garnet film (QuickTime Movie 2.4 MB)

     The bubble memories, which utilize magnetic garnet film, stores the information by creating, annihilation, and moving the bubble domains in the garnet. The bubble memories are non-volatile solid state mamories and robust compared to HDD since the momories have no mechanical components, so that the bubble memories and related materials had been extensively studied from 1967 to 1980s. Prof. Iwata also studied the domain dynamics in the magnetic garnet films in 1970s.
    The downloadable file on this page is the movie of the domain structure on the magnetic garnet taken by using the polarized optical microscope. First, the maze domain structure is seen, and then upward magnetic domains expand when the upward magnetic field is applied. If the large field enough to saturate the magnetization is applied, the magnetic domains disappear from the screen.
    If upward field is kept at a certain value and inductive field is applied from the current pulse flowing in the conductive lines located upper and lower part of the screen (two black bands can be seen on the screen), the stripe domains are cut by the inductive field. Further increase of the inductive field results in the formation of the bubble domains. The bubble domains can be moved by the field gradient created by the current in the conductive lines.