Heat Capacity of MgB₂: Evidence for Moderately Strong Coupling Behavior

Original · EN

We characterize the superconducting state of phase pure polycrystalline samples of the new layered superconductor MgB₂ by specific heat measurements in magnetic fields up to 9 T. The characteristic jump at the superconducting transition is observed and compared with the predictions of weak coupling BCS-theory and the α-model. Our analysis shows excellent agreement with the predictions for 2Δ/kBT C = 4.2(2) with a Sommerfeld term γ exp of 3.1(1) mJ/mol K² indicating that MgB₂ is a superconductor in the moderately strong electron-phonon coupling regime.