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.