Scientists have never seen this before: a material that has learning capabilities

C'est la première fois qu'une capacité d'apprentissage est observée chez un matériau. © Olga, Adobe Stock

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[EN VIDÉO] What are the differences between an insulator and a conductor at the quantum level?
Why are materials like gold, silver or copper good electrical conductors? Its secret is at the quantum level, mainly in the behavior of its electrons. Discover in video thanks to Everything Is Quantum the differences between an insulating and a conductive material.

Construction materials, smart materials, ecological materials…
A…” data-image=”” data-url=” .com/sciences/definitions/physics-material-15914/” data-more=”Read more”>material able to memorize stimulus external conditions it has been through and adapt to them, just as our brain works
Located in the braincase, the brain is the seat of higher functions (cognitive functions, senses, nerve responses) and vegetative functions. It is therefore an essential organ that regulates everything…” data-image=” .jpg” data- url=”” data-more=”Read more”>brain : difficult to imagine that this type of material exists, and yet the dioxide Generalities
Symbol: V Atomic number: 23 Electrons per energy level: 2, 8, 11, 2 Mass…” data-image=” b / d/fbde2147cd_73005_vanadium1.jpg” data-url=”” data-more=”Read More”>vanadium (OVtwo) is the first representative! This metal oxide A semiconductor would insulate at a temperature of zero kelvin (absolute zero), unlike a metal.
Semiconductors are widely used in…” data-url=”” data-more=”Read More”>semi conductor it was already known that it had a transition from insulator to metal, which made it perfect for uses in the field of electronics, or even more surprising ones, such as smart windows ! But researchers have discovered other surprising properties, described in a study published in Nature.

Originally, vanadium dioxide has an abrupt transition from insulator to conductor at 68°C: a mixture between a Mott Transition and one Peierls transition. When the temperature is lower than 68°C, the electrons of the OVtwo they are as if they were “attached” to atoms, due to the Coulomb repulsion between two atomic sites. But the energy provided by the heating of the material allows the electrons to get out of place and move in the VO2.

The Peierls transition, on the other hand, refers to the structure of the crystal lattice. The latter distorts below the transition temperature, creating a gap Between the two bands there is an energy gap in which a charge carrier cannot be found, this is a band…” data -image=”https:/ /cdn.futura-” data-url=” ” data-more= “Read more”>gap of energy between driving band and the valence band : electrons are not free to move in the material. But when the temperature increases, the distortion disappears, allowing the electrons to leave their atomic sites.

A chance discovery

already surprised by this transition from insulator to metal, vanadium dioxide is the subject of numerous studies, in order to determine in which fields it could be used. This is what Mohammad Samizadeh Nikoo, a doctoral student at the Swiss Federal Institute of Technology in Lausanne (EPFL), did. His initial goal was to study his so-called “volatile” memory, meaning that “the material returns to the insulating state just after removal of the excitation”specifies Samizadeh Nikoo in a EPFL press release, first author of the study. To do this, he sent many times to electric current in a sample of vanadium oxide. “An electrical impulse passes through the material and continues on its way to the exit”says the scientist.

The pulse allows the material to be heated and, therefore, to carry out the expected insulator-metal transition. Once the current has passed, cooling implies a return to the initial state of insulation. The researcher wanted to know how long this return to the isolated state took. But that’s where he noticed another surprising effect: the vanadium dioxide behaved differently during the second electrical impulsethe time to return to the insulating state was not the same as for the first pulse.

It was as if her structure had adapted to him. “Remember your last transition and anticipate the next one. This is an unexpected memory effect. This is not related to electronic states, but to the physical structure of the material. It is a novelty from the scientific point of view, because no other material behaves like this”says Elison Matioli, co-author of the study and director of the lab where the measurements were taken. Now, researchers have shown that this memory could last up to three hours. “If you remember it that long afterward, you can say that that memory can last for days, but we currently don’t have the measurement tools to test it.”continues E. Matioli.

One thing is certain: this discovery opens the gate too many Applications potential, especially for calculation operations that require memory. In fact, thanks to its strange behavior, vanadium dioxide is capable of storing more data (of different states) than conventional materials that are limited to information. binaries. In your case, we speak of structural memory, where the information is stored directly in the structural modifications you have made, while for other materials we speak of electronic memory, where only two electronic states are possible.

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