Acoustic Debye temperature and the role of phonons in cuprates and related superconductors

The Debye temperature of a superconducting material may provide information about the role of phonons in its superconducting mechanism. In this paper, the void-free acoustic Debye temperature, Theta(D), of various cuprate high temperature superconductors, estimated using the acoustic technique, was found to be in the range of 250-500 K. The electron-phonon coupling constant was estimated from the transition temperature T-c using the standard BCS theory and also the two-dimensional van Hove scenario with related characteristic temperature. The van Hove scenario seems to explain the high temperature superconductivity in the cuprates better than the standard three-dimensional BCS model. The Debye temperature of these copper oxide-based superconductors is compared with that of the new binary intermetallic MgB2 superconductor which has been reported to be a phonon-mediated superconductor.