Cooper Pairs and the BCS Model

Popular explanations of the Cooper pair formulate the coupling in the following way When the first electron passes, the nuclei are perturbed, and this simpMes for the second electron in its motion. However, many other possibilities exist for interpreting the Cooper pair, if such an interpretation is needed. 

Why do electrons in some cases behave as single electrons and sometimes as a pair of electrons when the temperature is lowered The mechanism for the Cooper pair explains some of the characteristics of superconductivity. If there is a gap, the pairing properties become visible because pairs of electrons obey the Bose-Einstein statistics and all condense into the lowest state. It costs energy to excite across the gap, therefore there is no resistance at low temperature. 

The Cooper pair model is the central part of the BCS model. For a long time, the latter model was the only accepted microscopic model for superconductivity. The BCS model is a free-electron model that correlates the motion of electrons and nuclei. Electronic correlation is not in question. 

The initial success of the BCS model has not continued in later years. Some elemental metals, for example, copper, silver, and gold, have so far refused to become supercomputing as T - 0 K, and there is nothing in the BCS model to suggest why this is the case. But worse problems were to come. 

New superconducting metals were discovered at a high rate, particularly by B. Matthias and his associates. In 1973, Tc= 23.2 K was reached for NbjBe and this 

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