Question

Discuss Cooper pairs on the basis of BCS theory.
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Answer 1

Answer:

Cooper pairs on the basis of BCS theory is defined as :

• The behaviour of superconductors suggests that electron pairs are coupling over a range of hundreds of nanometers, three orders of magnitude larger than the lattice spacing.
• These coupled electrons can take the character of a boson and condense into the ground state.
• This pair condensation is the basis for the BCS theory of superconductivity.
• The effective net attraction between the normally repulsive electrons produces a pair binding energy on the order of milli-electron Volts, enough to keep them paired at extremely low temperatures.

Explanation:

1. The transition is a metal from the normal to the superconductivity state has the nature of the condensation of the electron into a state which leaves a band gap between them.
2. This kind of condensation is seen with superfluid helium, but helium is made up of bosons multiple electrons can't collect into a single state because of Pauli Exclusion Principle.
3. The boson like behaviour of such electron pairs was further investigated by Cooper and they are called "Cooper pairs".
4. The condensation of Cooper pairs is the foundation of BCS theory of superconductivity.