PHONON DENSITY OF STATES AND SUPERCONDUCTIVITY IN ND1.85CE0.15CUO4

Inelastic-neutron-scattering techniques have been used to measure the generalized phonon density of states in superconducting Nd1.85Ce0.15CuO4. There is reasonable agreement at low energies between our measurements and recent point-contact-tunneling density-of-states measurements reported by Huang et al., which suggests that phonons play a major role in pairing in the electron-superconductor systems. The correspondence at higher energies, however, is not particularly good, but probably reflects the difficulty in obtaining quantitative tunneling data.