Acoustic de Haas van Alphen effect of CeRu2

The quantum oscillation of symmetrized elastic moduli of CeRu2 has been measured by an ultrasonic technique not only in the normal conducting state but also in the superconducting mixed state which includes the field region where a peak effect appears in the magnetization curve. The angular dependence of the oscillation frequencies for various branches in the normal state is identical to that previously obtained from a magnetic dHvA experiment by Hedo et al. The angular dependence of the quantum-oscillation amplitude is discussed in terms of the electron-phonon coupling. (orig.)