The world’s smallest magnetic data storage unit from just 12 atoms for each bit and 96 atoms for 8 bits i.e. 1 byte was designed by German Center for Free-Electron Laser Science (CFEL) and IBM scientists.
A scanning tunneling microscope (STM) was used to fabricate the nanometer data storage unit one atom at a time at the San Jose, California-based Almaden Research Center of IBM. Regular iron atom patterns were built arranged in rows, each row comprising six atoms. One bit is formed by two rows and a byte is sixteen rows. The area used is just 4 x 16 nm. According to CFEL researcher and lead author of the paper, Sebastian Loth, the storage density is 100 times higher than that in a modern hard drive.
The STM enables writing and reading of data from the nano storage unit. The atom row pairs have two magnetic states representing 0 and 1 of a standard bit. The STM tip emits an electric pulse, which switches the magnetic configuration. The configuration can be read using a weaker pulse, although nanomagnets are presently stable only at -268ºC temperature. The researchers anticipate that 200 atoms will be stable at room temperature. To use atomic magnets for data storage may still take some more time.
The researchers used the phenomenon of antiferromagnetism for data storage, which differs from ferromagnetism. In this, the spin of adjacent atoms is aligned oppositely making the material neutral magnetically at a high-volume level. Hence antiferromagnetic atom rows can be placed very close to each other without any magnetic interference. Hence bits just 1 nm apart were packed together.
This research has not just helped form the smallest magnetic data storage unit, but also enabled a transition from standard to quantum physics. Loth felt that this will enable them to answer a number of questions about quantum magnets.
Source: http://www.cfel.mpg.de