High-temperature superconductivity?
A rare phenomenon has such an amazing history as superconductivity - the discovery made by Camerling-Onnes in 1911. But all superconductors passed into the superconducting state at very low temperatures - near absolute zero. Is a remarkable phenomenon - superconductivity - always a low-temperature phenomenon? It turns out that back in 1964 the American Little spoke out an interesting idea about high-temperature superconductivity. In his hypothetical model, high-temperature superconductivity should occur at temperatures of the order of 10000 K!
It turned out that superconductivity arises because in metals between electrons there are small forces... of attraction. Of course, the Coulomb law is not canceled, and the two electrons continue to repel each other. But apart from this repulsion, in the metal there are also forces of attraction.
An electron in a metal is not an electron in a vacuum, it is surrounded on all sides by heavy ions forming a crystal lattice. Flying through a section of metal, the electron attracts surrounding ions to it and thereby tries to shift them a little. When another electron hits this place in a short time, he sees before him the ions perturbed by the first electron, and thus, as it were, "senses" his presence. Indirect interaction between electrons is transmitted through the displacement of ions and leads to the appearance of an attractive force.
In some metals, the attraction between electrons is greater than the Coulomb repulsion. They establish the order in the electronic movements, which the random thermal motion will for its part seek to destroy. But with a decrease in temperature, the effect of thermal motion will decrease, and sooner or later the metal must necessarily go into a superconducting state.
The fact that the transition temperatures in the superconducting state of ordinary metals and alloys are small is the result of the weakness of the attractive forces that arise between the electrons. Is it possible to arrange something so that the forces of attraction between electrons do not arise from the displacement of ions, but, say, from the displacement of lighter electrons? Electrons are much lighter than ions, they will be displaced much more willingly. The forces of attraction will increase greatly, and together with them the temperatures of the superconducting transition will also increase. It is only necessary to separate the electrons participating in the conductivity somehow from the electrons that provide the attraction between them.
Imagine a one-dimensional chain of atoms, for example, carbon, or some other element through which an electric current can flow. We attach to the sides of this chain at some distance from each other large groups of atoms that can easily polarize. Electrons of this group will easily move from one end to the other under the action of an electric field. The electron of the conducting chain, flying past each side group, will cause the displacement of its electrons. And another conductive electron will feel the effect of this displacement. And between the conduction electrons again there will be an effective attraction, as in the case of ion transport. Only now it will be much more. Calculations show that at temperatures of the order of 10000 K, high-temperature superconductivity should arise!
