Magnetic holographic memory

"Purpose"
Photopolymer that is a type of write-once material is the famous material used as a hologram medium. write-once type medium. A type of rewritable medium will be desired because of the enlargement of information. Presently, LiNbO3 is widely known as a good photorefractive material for rewritable media; however, we focus on magnetic media that have an ability of strage, essentially.

Principle
The process to fabricate the magnetichologram is similar to one of thermomagnetic writing. When the pulse laser goes to the saturated magnetic medium, interference pattern (hologram) is made in the medium corresponding to temperature distribution (Fig.1 (a)). The point where temperature is over the Curie temp. is demagnetized (Fig. 1(b); in the process of decreasing of temp., magnetization direction is reversed and the domain corresponding to hologram is wrote.


Fig.1 Principle of formation for magnetic hologram memory.
Present and future
We already verified recording and reading of magnetic hologram memory in experiments. In Fig. 2, the domain wrote by interference system is observed using a polized light microscope. The domain was erased when the applied field was on.  In the next step, we will evaluate detail of the magnetic hologram method and search material proper to hologram memory.

Fig.2 Magnetic hologram image

Fig.3 Magnetic hologram image
(applied field)