Understanding of Low Temperature Superconductivity —— About Physics

At present, it is generally believed that at room temperature, metal can be regarded as an "electron ocean" composed of outer electrons and a metal cation fixed in the lattice position. Driven by the potential difference, free electrons generate a certain average moving speed on the basis of the original thermal motion, and the whole electron moves in the direction of potential driving. However, there is a certain chance that free electrons will be scattered by metal ions (other electrons it carries), lose kinetic energy, and aggravate the overall thermal motion of metal. Macroscopically, the conductor will heat up and produce resistance.

When the metal is below the superconducting transition temperature, it is generally believed that two electrons with equal momentum, opposite direction and opposite spin attract each other to form bound electron pairs. As a whole, this electron pair is no longer a fermion, but a boson, and its scattering mechanism by metal ions (the electron clouds of other electrons it carries) has changed, thus greatly reducing the energy loss caused by scattering. Macroscopically, the resistance suddenly drops to a level close to zero, which is what we call it. This theory was put forward by Badin, Cooper and schrieffer, and it is called BCS theory.

Superconducting state does not mean that the resistance is absolutely zero, but the resistivity suddenly drops to a very low level compared with the normal temperature state. In fact, superconductors will certainly generate heat at high current, but the heat generation is much smaller.

As for some high-temperature superconducting materials at present, their superconducting principles are very complicated. At present, there are different views in the field of solid state physics, and as far as I know, there is no good theory to explain it.