The researchers both constructed and wrote data to the tiny memory elements using a scanning tunneling microscope, a device developed at IBM Zürich in 1981. This microscope has a very thin conducting probe that can be used to image a surface and push individual atoms around.
Heinrich says his team found it could make antiferromagnetic memory using fewer than 12 atoms, but these were less stable. With 12 atoms, the memory elements obey classical physics, and the read-and-write pulses applied through the microscope probe are similar to those used in today’s hard drives. This research is described today in the journal Science.
Any realistic nonvolatile data storage technology has to be able to hold onto the data for 10 years at temperatures well over room temperature, says Victor Zhirnov, a research scientist at the Semiconductor Research Corporation, who was not involved with the work. The IBM bits can hold onto a 1 or a 0 for just a few hours, and only at very low temperatures, but Heinrich says it should be possible to increase their stability for operation at more realistic temperatures by using 150 atoms per bit rather than 12—still a miniscule number compared to existing forms of memory.
However, making a realistic technology was not the aim of the current work, says Heinrich. His aim is to explore whether other kinds of computing elements can be made from a few atoms, perhaps by embracing quantum. “We have to have the foresight not to worry about the next step, but to jump to something potentially revolutionary,” he says.