Scientists did not have such material with educational capabilities before!

material capable of preservation Energizing The external circumstances it has been through and adapting to, just like us brain : It is hard to imagine the existence of this type of material, however, vanadium dioxide (VO₂) is the first actor! It was already known that this semiconductor metal oxide has an insulator-to-metal transition, making it ideal for uses in electronics, or even other, more fascinating uses, such as smart windows ! But researchers have discovered other surprising properties, described in a study published in temper nature.

Originally, vanadium dioxide moved abruptly from insulator to conductor at 68°C: a mixture between Move Mott and one Peierls . transmission. When the temperature is less than 68°C, the Electrons from VO₂ It is as if “attached” atoms, due to Coulomb repulsion between two atomic sites. But’energy By heating the material the electrons are allowed to leave their position and move into VO2.

On the other hand, the Peierls transition relates to the structure crystal lattice. The latter is deformed below the transition temperature, creating a coil the difference of energy between Delivery range and the equivalence range : Electrons are not free to move around in matter. But when the temperature rises, the distortion disappears, allowing the electrons to leave their atomic positions.

Accidental discovery

It’s really amazing for this Transition from insulator to metal, vanadium dioxide is the subject of numerous studies, in order to determine the areas in which it can be used. So did Mehmet Samizadeh Niko, a doctoral student at the Swiss Federal Institute of Technology in Lausanne (EPFL). Its initial purpose was to study his so-called “varying” memory, that is, to say so “The material returns to the insulating state after the excitation is removed”Samizadeh Nikoo identifies in the format EPFL Press Release, first author of the study. For this, send several times a Electric current in the vanadium oxide sample. Electrical impulses pass through the material and continue on their way to the exit.says the world.

The pulse makes it possible to heat the material and, accordingly, to make the expected transition between the insulator and the metal. Once the current has passed, cooling involves returning to the initial insulating state. The researcher wanted to know how long it took for this to return to the buffer state. But this is where he noticed another cool effect: vanadium dioxide behaved differently within a second electric impulsethe time to return to the insulator state was not the same as for the first pulse.

It was as if her structure had adapted to it. “It remembers its last transition and anticipates the next. This is the unexpected memory effect. This is not about electronic states, but about the physical structure of matter. It is a novelty from a scientific point of view, because no other matter behaves like this”says Ellison Mattioli, co-author of the study and director of the laboratory where the measurements were made. Currently, researchers have shown that this memory It can last for up to three hours. “If he remembers it after a long time, it is possible to say that this memory can last for several days, but we currently do not have the measurement tools to prove it”E. Mattioli continues.

One thing is for sure: this discovery unlocks Gate too much apps potential, especially for calculations that require memory. In fact, thanks to its peculiar behavior, vanadium dioxide is able to store more data (from different states) than traditional materials that are limited to information. binaries. In his case, we are talking about structural memory, where information is stored directly in the structural modifications he has made, while for other materials, we are talking about electronic memory, in which only two electronic states are possible.