Electronic specific heat of two-band layered superconductors: Analysis within the generalized two-band α model

摘要

The generalized two-band α model of superconductivity is consistently developed by taking into account the interband electron-phonon interaction. The model is applied to calculate the electronic contribution to the specific heat, superconducting gaps, and electron-phonon coupling constants of the multiband layered superconductors MgB_2 and Ba(Fe_(0.925)Co_(0.075))_2As_2. For both compounds, the energy gaps and electron-phonon coupling constants are determined, and the temperature behavior of the specific heat is obtained that describes the experimental data well. It is shown that the well-known two-band α model that assumes independent bands is formally valid only in the case of relatively strong interband scattering in the band with a smaller gap.