Description
The concept of Cooper pair and its usage in the science of superconductivity is analyzed from the historical and scientific perspective. It is shown that very often “Cooper pairs” are considered as separate entities existing outside the collective state of the superconducting metal (in the majority of cases, this state is treated by the Bardeen-Cooper-Schrieffer (BCS) theory or its extensions). In particular, whenever the double elementary charge 2e enters the superconducting phenomenon, such as, e.g., non-stationary Josephson current, this phenomenon is attributed to the single Cooper pair manifestation. In fact, this feature really originates from the Cooper pairing, being the charge quantum of the composite BCS wave function and characterizing this complicated object. It is shown that the overuse of the Cooper pair concept may be misleading and detrimental to the teaching of superconductivity confusing the BCS theory with its alternatives, where Cooper-like pairs treated as separate “molecules” are considered as the constituents of the superconducting electron liquid.
