Specific heat of MgB₂in a one- and a two-band model from first-principles calculations

The heat capacity anomaly at the transition to superconductivity of the layered superconductor MgB 2 is compared to first-principles calculations with the Coulomb repulsion, * , as the only parameter which is fixed to give the measured T c . We solve the Eliashberg equations for both an isotropic oneband model and a two-band model with different superconducting gaps on the -band and -band Fermi surfaces. The agreement with experiments is considerably better for the two-band model than for the one-band model.