ABSTRACT
Superconductors whose properties can be described by the BCS theory are called conventional superconductors. The others are called unconventional superconductors. Formation of Cooper pairs and their frictionless flow is central to the theories of superconductivity that have been proposed so far. Simultaneously, the nature of interaction between the charges constituting the Cooper pair is an important parameter. This viewpoint is supported by the fact that the magnetic flux quantum is the same for all superconductors since it is composed of two universal constants and is due to the motion of Cooper pairs that carry the electric charge whose value is 2e. Thus, for such an interaction to be constant, it should be composed of some universal constants, and we are yet to discover and predict this interaction. Calculations have been done using the existence of some fundamental forces between the electrons in the Cooper pair to see if such an interaction can be discovered. It is noted that the binding energy of Cooper pair depends on universal constants, except the effective mass that may vary from superconductor to superconductor. It is possible that the variation of leads to different transition temperatures Tc for various types of superconductors.
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