BCS theory

BCS theory

1. Electron passes lattice and interacts with phonon. The phonons emit when they interact with lattice ions.

   • Emitted phonon creates lattice distortion and an area of positive charge density. This is because the positive ions attract to the electron's negative charge
     • This positive distortion attracts another electron some distance away before the distortion is removed and the electron passes the ion.
       • The exchange of phonons ensures the indirect attraction between the electrons (cooper pair).
         • When the phonon is emitted is vibrates to other neighbouring lattice ions to be absorbed by another electron
           • Therefore, no energy is lost in the cooper pair formation (mention equal and opposite). This ensures they travel unimpeded with zero electrical resistance.