Magnetic bubble memory consists of magnetic bubbles used to store data bits. These bubbles move in thin films of magnetic material. The bubbles are cylindrical magnetic domains having polarization opposite to that of the thin film in which they are embedded.
A thin film of magnetic garnet contains wavy strips of magnetic domains when an external magnetic field is applied perpendicular to the film and increased slowly, the wavy magnetization strips having magnetization opposite to the external field begin to narrow. At a certain value of field strength all these domains contract and look like small circular bubbles. These bubbles are tiny magnetic floating in an external field. These bubbles can be moved by applying a magnetic field parallel to the film. To control the direction of movement, special magnetic paths are created by depositing magnetically conductive material in the specific pattern on the film.
The main components of magnetic bubble memory are thin film memory chip, drive coils, permanently magnetized control electronics. Logical 1s and 0s are represented by presence or absence of bubbles respectively.
Applications of Magnetic Bubbles
It can store a large number of data bits. The storage is non-variable and is not erased if power is disconnected.
The only disadvantage of this memory is that access time is high. This is because of the reason that data has to be accessed serially. Random access is not possible.