Heat Capacity from BCS Theory

An abrupt change in heat capacity is observed as the material is cooled into the superconducting state. Instead of following the yT behavior characteristic of the electronic component at low temperatures, the heat capacity in the superconducting state exhibits a Boltzmann-like behavior. 

The 2Aq represents the energy gap centered on the Fermi level and the 2kT is to account for the two electrons forming the Cooper pair. The BCS theory (Equation 26.4) predicts that this energy gap, 2Aq = 3.51fcTc and this relationship appears to be satisfied by a wide range of superconductors. The constant can be determined by integrating Csc(T)/T from 0 to Tq and equating this to the entropy at Tc which is jTc- 

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