(ORDO NEWS) — It is not alive and has no structures even approaching the complexity of the brain, but the researchers found that a compound called vanadium dioxide is able to “remember” previous external stimuli.
This is the first time this ability has been revealed in a material; but he may not be the last. The discovery has rather intriguing implications for the development of electronic devices, in particular for data processing and storage.
“Here we report electronic long-lived structural states in vanadium dioxide that may provide a circuit for data storage. and processing,” writes a team of researchers led by electrical engineer Mohammad Samizade Niku from the Federal Polytechnic School of Lausanne in Switzerland in their article.
“These glass functional devices can outperform conventional metal oxide semiconductors. electronics in terms of speed, power consumption, and miniaturization, as well as provide a path to neuromorphic computing and multi-level memory.”
Vanadium dioxide (VO 2 ) is a material that has recently been proposed as an alternative or addition to silicon as a base for electronic devices due to its potential to outperform the latter material as a semiconductor.
One of the most intriguing properties of VO 2 sub> is that below 68 degrees Celsius (154.4 degrees Fahrenheit) it behaves like an insulator, but above this critical temperature it abruptly switches to a highly conductive metal, a change known as metal-insulator transition.
Only recently, in 2018, scientists figured out why: as the temperature rises, the way atoms are arranged in the lattice changes.
When the temperature drops again, the material returns to its original insulating state. Samizade Niku originally set out to investigate how long it takes VO 2 to go from insulator to metal and vice versa by taking measurements as he triggered the switch.
It is these measurements revealed something very peculiar. Although VO 2 returned to the same initial state, it behaved as if it remembered recent activity.
The experiments involved injecting an electric current into a material that traveled a precise path from one side to the other. This current heated VO 2 , causing a change in its state – the rearrangement of the atomic structure mentioned above. When the current was removed, the atomic structure relaxed again.
When the current was turned on again, things got interesting.
“VO 2 seemed to ‘remember’ the first phase transition and anticipate the next one,” explains electrical engineer Alison Matioli of EPFL.
“We did not expect to see such a memory effect, and it has nothing to do with electronic states, but rather with the physical structure of the material. This is a new discovery: no other material behaves in this way.”
The group’s work showed that VO 2 stored some information about the last applied current for at least three hours. In fact, it could be significantly longer, “but we currently don’t have the tools we need to measure it,” says Matioli.
This switching is reminiscent of the behavior of neurons in the brain, which serve as the unit of memory and processor. Described as neuromorphic technology, computing based on a similar system can have a real advantage over classic microchips and printed circuit boards.
Because this dual property is inherent in the material, VO 2 seems to tick all the boxes on the wish list for memory devices: the potential for high capacity, high speed, and scalability. In addition, its properties give it an advantage over memory devices that encode data in a binary format controlled by electrical states.
“We have reported glassy dynamics in VO2 that can be excited on subnanosecond scales and controlled over several orders of time, from microseconds to hours,” the researchers wrote.
“In this way, our functional devices have the potential to meet the continuous demands of electronics. in terms of scaling, fast operation, and reduced power levels.”
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