The Nature of the Cooper Pair - University of Liverpool

At temperature T , we would expect thermal energies of the
order of k BT , either in the form of phonons or excited
electrons. If this energy is more than ∆, then there is enough
energy to break the Cooper pairs. If this happens, the metal
returns to being normal conducting, with resistance.
The transition temperature Tc is therefore related to the
binding energy by
k BTc ≈ ∆.
The complete BCS theory gives the more accurate relation of
1.76k BTc = ∆
which agrees well with measured values of Tc and ∆.
Superconductivity 31