Superconductors - BCS theory

[5614]

Can someone explain the reaction that occurs between electrons and phonons in a superconductor?

 

I mean, I understood the whole cooper pair thing, but how do phonons come into it?

[5614]

*bump*

 

does anyone know?

[timo]

Well, being a superconductor implies no resistance. As electron-phonon interaction is part of electrical resistance (if I remember that correctly) I´d suspect that there´s no interaction with the phonons in a superconductor.

But maybe you could explain about cooper-pairs if you understood them. Because I haven´t understood how two electrons can form a bound state so far.

[5614]

Electrons moving through a conductor cause a slight positive charges in the area around it... this +charge can attract another electron. In effect two electrons are then bonded with a certain binding energy.

 

[edit] the electrons have opposite spin, don't know why but they do!

 

As electron-phonon interaction is part of electrical resistance

I have also read that:

'the attractive interaction between electrons (which causes cooper pairs) is brought about indirectly by the interaction between the electrons and phonons.'

but I do not fully understand the why/how of the interaction between electrons and phonons, but then I didn't know what you said (in the quote), so if you don't know the answer to the original question could you expand/explain that please?

[5614]

http://hyperphysics.phy-astr.gsu.edu/hbase/solids/bcs.html

A key conceptual element in this theory is the pairing of electrons close to the Fermi level into Cooper pairs through interaction with the crystal lattice. This pairing results from a slight attraction between the electrons related to lattice vibrations; the coupling to the lattice is called a phonon interaction.

[5614]

furthermore:

 

BCS theory is present based on "the fact that the interaction between electrons resulting from the virtual exchange of phonons is attractive when the energy difference between electron states involved is less than the phonon energy."

 

from here: http://academic.sun.ac.za/summerschool/2005/documents/lecture_notes/trivedi/trivedi_lecture3.pdf