IBM scientists have stored a memory bit on 12 atoms of magnetic material at low temperature. They have also fabricated a device utilising eight 12 atom bits to make a memory byte.
IBM believes that a device which would be stable at room temperatures would require 150 to 200 atoms.
A scanning tunnelling microscope was used to arrange the atoms in such a way that their magnetic properties did not interfere with the properties of neighbouring atoms which is often the case in small geometry magnetic memories.
Data is stored on rows of iron atoms, on a Cu2N layer over a copper substrate.
12 atoms in two rows are sufficient to store 1 data bit a 0.5K with a spontaneous switching rate (error rate) of one per 2-3 hours per byte.
Below 12 atoms, IBM believes, quantum effects will make the technology unviable.
44 years ago, IBM’s Bob Dennard, invented the DRAM which remains the largest selling memory on the market.
The 12 atom bit is 400 times denser than today’s RAM bit.