Phonon Spectrum of the Ferromagnetic Superconductoruge2and Consequences for Its Specific Heat

We report inelastic neutron scattering measurements of the phonon spectrum of the pressure-induced ferromagnetic superconductor UGe2. The phonon contribution to the specific heat was estimated from a fit to our data. The excess specific heat previously noted at around T-x approximate to 30 K is not due to phonons but is well described by the temperature dependence of the magnetic order parameter at the molecular field level.