A Brief Background

Super conductors had been observed since 1911, but an acceptable interaction between electrons had not been found to explain the assorted superconductive effects.  Welker explored using a magnetic interaction due to all the moving charges in 1939, but this was as unsuccessful as Heisenberg’s attempt in 1947 where he tried to use the electron repulsion to lead to a form of collective spatial ordering.

Steps were first taken towards a suitable explanation, when in 1950, Fröhlich showed that an electron-phonon interaction, where one electron emits a phonon, which is then absorbed by another, could couple two electrons together.  Later that year Cooper showed that this attractive force could lead a pair of electrons to couple and have a collective energy lower than 2ε_f, the energy they’d have if they were individual free electrons, if they were inserted into a metal at absolute zero.  The only problem was that Coopers’ theory only applied if you ignored the pairs’ interactions with the rest of the electrons in the metal.

However it wasn’t until 1957 when Bardeen, Cooper & Schriefer showed that Coopers’ model for coupling of a single pair of electrons could be generalised to the 10²³ electrons within a cm³.

The Nobel Prize in Physics 1972[1]
John Bardeen  (B)	Leon Neil Cooper  (C)	John Robert Schrieffer  (S)
University of Illinois	Brown University	University of Pennsylvania

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