Vibrational spectroscopy of superconducting MgB2 by neutron inelastic scattering

Neutron inelastic scattering measurements have been performed on superconducting MgB2 above and below T,. The temperature dependence of the generalized phonon density-of-states showed clear anomalous behaviour near 24 meV in the acoustic phonon region, which may be interpreted as evidence of a substantial contribution to the total electron-phonon coupling strength deriving from these phonons. Weaker evidence for a corresponding response in the high-energy B bond stretching phonons was also encountered.