In short: Scientists at the Ecole Polytechnique Fédérale de Lausanne (EPFL) in Switzerland have discovered by chance that a material used in electronics can “remember” its history of previous physical stimuli. Exploited in the right way, the material and its new behavior could have a considerable impact on the memory of electronic devices.
It is the first material known to have this ability, but others may exist.
Doctoral student Mohammad Samizadeh Nikoo was looking for phase transitions in vanadium dioxide – more specifically, how long it takes for the material to change from one state to another. When the material reaches 68 degrees Celsius, it undergoes an abrupt transition from insulation to metal. His tests involved applying an electric current to a material, causing it to heat up (and change state) as it moves from side to side. Once the current passes, the material cools and returns to its original state.
After registration hundreds of measurements, Nikoo detected a memory effect in the structure of the material. By applying a second current pulse to the material, he noticed that the time it took to change state was directly related to its history.
“VO2 seemed to ‘remember’ the first phase transition and anticipate the next one,” said Professor Elison Matioli, who leads the lab where the discovery was made. “We didn’t expect to see this kind of memory effect, and it has nothing to do with electronic states but rather with the physical structure of the material,” added the professor.
Further testing revealed that the material can remember its most recent stimuli for up to three hours. The memory effect may even persist for longer – perhaps even days – but the team lacks the instruments to make these measurements.
The publication notes that the finding apparently replicates what happens in the brain, with VO2 switches acting like neurons. “No other material behaves this way,” Matioli said.
A material that could improve computational performance through greater capacity, miniaturization, and speed would be a boom for electronics makers, and VO2 could do just that. It also differs from traditional materials that store data as binary information based on the manipulation of an electronic state.
The team’s work has been published in the journal Nature.
Image credit: Chokniti Khongchum