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It turned out that a new theory is explaining the nature of superconductivity.
Physicist Victor Lakhno Institute of Applied Mathematics. MV Keldysh suggested that the explanation of superconductivity translational-invariant theory bipolarons. Possible solutions to the problem of superconductivity at room temperature. The corresponding article was published in Advances in Condensed Matter Physics.
Currently working on getting new superconductors that can work at temperatures above absolute zero, goes around the world. However, in fact it is empirically acceptable to all physicists, the theory of how superconductivity is possible at high temperatures, does not yet exist. But rather a lack of theory means that the search for such materials are almost blind, brute force.
Classical theory of superconductivity – BCS (the names of its developers, John Bardeen, Leon Cooper and John Shiffer) – Kelvin (about -270 degrees Celsius). However, in 1986, Celsius, and today managed to reach even -70 degrees Celsius.
It has become clear that we need some new theory. One of the hypotheses that it was bipolaron. It comes from the fact that superconductivity is due to the transitions of an ideal three-dimensional Bose condensate. translational-invariant bipolaron (TI-bipolarons). The condensate of Bose – Einstein is the fifth aggregate state of the matter predicted by Einstein in 1925, and carried out in the experiment in 1995. the researchers used a gas of rubidium atoms cooled to almost absolute zero. With this cooling of all particles in the Bose-condensate, moving in concert to form a single quantum-mechanical wave and behave like one giant particle. They are both in the same place, and each of them at the same time, “smeared” across the area of space. Earlier Viktor Lakhno mathematically proved that a Bose condensate can be formed from the quantum Bose-gas, which, in turn, consists of a translational-invariant bipolaron.
A polaron is a quasiparticle of an electron and the disturbance that it produces, through the crystal lattice of the substance. Such perturbations are called phonons. Bipolaron – two polaron connected mironovym interaction. Victor Lakhno were able to show that bipolaron can possess the translation invariance, that is, to provide a flat wave in the crystal lattice.
Flat waves. Scientist proved theoretically that the translational-invariant bipolaron can create a stable Bose condensate, even at room temperature. This means that the superconductivity is at such high temperatures.
In their calculations it came from the same initial positions and the classical theory BCS. However, he considered the electron-phonon interaction in the superconductor is not as simple as pure electronic, with exception of the phonon variables, but rather as a phonon, by excluding from the calculation of the variables with respect to the interaction of the electrons. that are related to the interaction of phonons.
In the case of linear dispersion law, the form of Bose-Einstein condensate. However, in the case of materials, that become superconductors at room temperature, according to the theory of Lakhno, we are not dealing with sound, and with optical phonons: since these materials are ionic crystals have an optical nature.
As a result, the theory describes a charge Bose gas of pairs associated with electrons, optical phonons, which is a translational invariant (TI) bipolaron, not just pairs of electrons, both in the classical BCS theory. The qualitative difference between the new theory and the others is that T-bipolarons, that is, in coupled condition, which provides superconductivity, even at zero temperature. . This is due to the results obtained in the experiments in 2016, and opens up entirely new perspectives in the creation of the room of superconductors. As for the transition to a state of superconductivity, it is not necessary to do all the paired electrons of the material, and it is only necessary to increase the concentration of T-bipolaronic.