Regime change: what prospects does the "e-liquid" offer
Conventional ideas about electricity may change markedly in the coming years. An international team of physicists has reported observing an unusual state of electrons in graphene — they begin to behave as a single stream, similar to a liquid with almost zero internal friction. This discovery not only helps to better understand the behavior of matter at the quantum level, but can also become the basis for new technologies. The information about what exactly the researchers found and what it will lead to is in the Izvestia article.
When electricity becomes a liquid
Usually, an electric current is represented quite simply: electrons move along a conductor, collide with atoms and gradually lose energy, turning it into heat. But in graphene, a material only one atom thick, the usual pattern can completely change. For the first time, an international team of physicists from the Indian Institute of Science and the National Institute of Materials Science of Japan has been able to experimentally capture a regime in which electrons behave not as individual particles, but as a single stream resembling a liquid.
To see this effect, the scientists had to create ultra-pure graphene samples, practically free from defects. Under such conditions, electrons stop "stumbling" over impurities and begin to actively interact with each other. The result is a collective movement — a coordinated flow that looks really similar to the flow of a liquid. Researchers use the image of water for a reason: if in an ordinary conductor the current is more like a stream of sand, where particles constantly collide and slow down each other, then here it is a smooth flow with minimal losses.
However, as explained by Nikolai Klenov, Vice-rector for Research at MTUCI, Professor at Moscow State University, the term "e-liquid" should not be taken literally.
— This is not a new state of aggregation of matter, but a special mode of behavior of electrons inside a solid. We are talking about the collective dynamics of quasiparticles, when strong interactions between electrons play a key role. They are the ones that create the "fluidity" effect, he notes.
This mode is most clearly manifested in the so—called Dirac point, a special state of graphene at the boundary between the metal and the insulator. Here, the electrons lose their "individuality" and begin to move synchronously. In this state, which has been dubbed the "Dirac liquid," the material exhibits behavior that is unexpected even by physicists. For example, it turned out that heat and electric charge propagate in it in different ways, although in ordinary metals these processes are closely related.
— Classical physics describes their relationship through the Wiedemann–Franz law, but in the experiment the deviation turned out to be more than 200 times. It looks like a violation of a fundamental law, but in fact it simply stops working under these conditions. In the Dirac liquid mode, heat and charge are transferred by different mechanisms: heat is transferred by collective excitations, and electric current is transferred by the movement of charges," Klenov emphasizes.
At first glance, these are the subtleties of basic science, but it is precisely such effects that can become the basis of future technologies. If the electrons are able to move in concert, with minimal losses, this opens the way to more efficient electronics and ultra-sensitive sensors. In this sense, graphene is turning into a kind of laboratory where you can not only observe unusual quantum phenomena, but also learn how to control them, which means that you can bring closer the appearance of devices that today seem to be pure theory.
Why it can change electronics and sensors
If the first observation of an "electronic liquid" in graphene is, first of all, a fundamental science, then the next logical question is how and where it can be useful in practice. And here, according to experts, the technology does have potential, although the path to mass adoption will not be quick.
Nikolai Klenov explains that, in theory, such effects open up the possibility of creating fundamentally new devices. The information carrier is no longer just an electrical voltage, as in modern electronics, but the flow of the "electronic liquid" itself.
In practice, this can lead to the appearance of hypersensitive sensors. For example, devices capable of detecting extremely weak magnetic fields or electrical signals are in demand in medicine (for recording brain and heart activity), navigation, and scientific measurements. In addition, the hydrodynamic mode of electron movement theoretically allows to reduce energy losses, which means to reduce heating and increase the efficiency of microelectronics.
— In order for electrons to start behaving like a "liquid", we need an almost ideal material — ultrapure graphene without defects. Such samples are already being obtained in the laboratory, but transferring this quality to large areas and making mass production is an extremely difficult task. The transition to the hydrodynamic regime in large synthesized films is a serious technological challenge," Klenov believes.
Nevertheless, the situation looks more encouraging than it might seem. Graphene technologies in general are already moving beyond the laboratory. According to the expert, the first graphene-based sensors actually already exist and are starting to appear on the market. So far, they have not fully exploited the e-liquid effect, but they demonstrate that the material itself is ready for commercial use. According to experts, this process may accelerate in the next 3-5 years.
Where will the technology appear first
New graphene technologies will be the first to appear where sensitivity and accuracy are critical, and high cost is not an obstacle. According to Nikolay Klenov, the main beneficiaries include the defense and aerospace industries: ultra—sensitive detectors, magnetometers and night vision systems.
An equally noticeable effect is expected in medicine. Graphene opens up possibilities for creating compact biosensors, as well as devices for rapid diagnostics, for example, by the composition of exhaled air. In the long term, these are new-generation neural interfaces capable of reading brain signals more accurately.
Another important area is telecommunications. This is where graphene can play a key role in the transition to next—generation 6G networks. We are talking about working in the terahertz range, where traditional materials currently face serious limitations.
"Ultra—sensitive terahertz radiation detectors have already been created based on graphene, which are potentially capable of providing terabit data transfer speeds — this is an order of magnitude higher than today's standards for mobile communications and Wi-Fi. Russian research groups are also working on graphene films and receivers for the subterahertz range," the professor emphasizes.
The main limitation now is the high cost and complexity of graphene production. However, as synthesis and roll printing technologies evolve, it will gradually move out of laboratories and into mass electronics. Experts expect its price to decline rapidly along a trajectory similar to that of silicon and other key materials.
At the same time, physicists are increasingly calling graphene a "quantum laboratory on a chip." In such systems, it is possible to simulate states of matter that are simply inaccessible under normal conditions.
— Today, graphene structures are used to study effects related to black hole physics, quantum entanglement, and topological states of matter. By controlling the parameters of the material — from the concentration of carriers to the geometry of the layers — researchers actually "construct" new types of matter with specified properties, says Klenov.
In this sense, graphene is becoming a universal tool for science and technology. And as the Izvestia interlocutor summarizes, such research is not only a fundamental interest, but also a signal for the development of interdisciplinary areas where physics, materials science and telecommunications begin to work together.
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