- #1
- 5,779
- 172
BCS theory is able to derive the London equations and the Meißner-Ochsenfeld effect.
Experimentally the Meißner-Ochsenfeld effect can be demonstrated via levitating superconducting rings. So we have the usual Lorentz force acting on the Cooper pairs carrying the current. However in order to lift the ring the force has to act on the ring i.e. on the lattice as a whole. But there is no interaction between Cooper pairs and the lattice due to the energy gap seperating the BCS ground state from the 1st excited state.
So my question is how the force can act on the ring w/o having any interaction between the Cooper pairs and the lattice?
Let me speculate that due to the disperison relation of accustic phonons
##\omega(k) = c_S\,k##
there is a coupling of two effective d.o.f., namely the ground state of the Cooper pairs and the lattice, which allows for a collective mode at k=0 w/o energy gap for the phonons. This would correspond to a movement of the lattice as a whole.
EDIT: any ideas regarding this critical paper? http://iopscience.iop.org/1402-4896/85/3/035704/
Experimentally the Meißner-Ochsenfeld effect can be demonstrated via levitating superconducting rings. So we have the usual Lorentz force acting on the Cooper pairs carrying the current. However in order to lift the ring the force has to act on the ring i.e. on the lattice as a whole. But there is no interaction between Cooper pairs and the lattice due to the energy gap seperating the BCS ground state from the 1st excited state.
So my question is how the force can act on the ring w/o having any interaction between the Cooper pairs and the lattice?
Let me speculate that due to the disperison relation of accustic phonons
##\omega(k) = c_S\,k##
there is a coupling of two effective d.o.f., namely the ground state of the Cooper pairs and the lattice, which allows for a collective mode at k=0 w/o energy gap for the phonons. This would correspond to a movement of the lattice as a whole.
EDIT: any ideas regarding this critical paper? http://iopscience.iop.org/1402-4896/85/3/035704/
Last edited: