Calculated elastic properties of MgB2 at the superconducting transition

The elastic properties of the intermetallic MgB2 superconductor at the superconducting transition temperature are calculated using various thermodynamic data. Our calculations show that a step discontinuity of 66 ppm in the bulk modulus and 76 ppm in the Youngʹs modulus are expected at the superconducting transition. A step discontinuity of 21 ppm in the longitudinal sound velocity is also expected at the transition temperature. Such anomaly should be detectable by most elastic measurements. The calculated acoustic Debye temperature is 880±30 K and this is within the range of values determined by various non-acoustic methods. The electron–phonon coupling constant calculated for the weak and strong coupling limit of the BCS theory as well as the two dimensional van Hove scenario shows that MgB2 is a moderately strong-coupled BCS type superconductor.