Data storage units, as thin as a few strands of hair, may soon be on the cards. IBM and the German Center for Free-Electron Laser Science (CFEL) have come up with a new size of the byte and it’s the world’s smallest data storage unit. The storage unit – one bit – comprises just 12 atoms! The byte – or 8 bits – thus comprises just 96 atoms, far less than the 500 million atoms that normal hard drives of today take!
This amazing fabrication comes from the IBM Almaden research Center in San Jose, California. They made up two rows of iron atoms, each row being six atoms long. Each atom was placed carefully on the substrate using a Scanning Tunnelling Microscope (STM). This formed one byte. The team then made 8 such structures. Each byte covers just 4 nm x 16 nm area (nm = nanometer; 1 nm = One billionths of a meter).
Using Spin States
The storage is done using the spin states of the ferromagnetic iron atoms. The two states – 0 and 1 – representing on and off respectively, are simulated by the spin being either parallel or anti-parallel to a certain direction. The state can be changed using the STM, employing a tiny electric pulse. Thus data can be written into and also read out of these tiny atomic magnetic units. The electric pulse, only a few nano amperes strong, can only be stable at very low temperatures like 5 Kelvin or minus 268 degrees Celsius.
The revolutionary idea, as compared to the conventional storage devices, is the use of anti-ferromagnetic order of the adjacent iron atoms. This means that two neighboring toms will have two different states of spin – one will be ‘up’ and the other ‘down’. This will make the bulk material non-magnetic.
Building bottoms-up starting from single atoms is by no mean task! Only a very few research facilities in the world have been able to master the wizardry. But, why 12 atoms? Sebastian Loth, who migrated from IBM to CFEL and is the lead of the study explains it:
Beneath this threshold quantum effects blur the stored information.
There is a long way to go for these atomic devices to be made available for public use.
The paper highlighting this new fabrication appeared on Science (link) on 13th January, 2012.