ELASTIC ANOMALIES IN HEAVY FERMION COMPOUNDS

We studied elastic constants, ultrasonic attenuation and a.c.-susceptibility in the normal and superconducting states of the heavy fermion compounds UPt3 and CeCu2Si2. In the normal state of CeCu2Si2 we observe crystal electric field-, Gruneisen parameter coupling- and magnetic fluctuation-effects. We present a B-T phase diagram for the magnetic and superconducting phases. In UPt3 we concentrate on the superconducting behaviour, mainly on the splitting of the transition as a function of temperature as well as of magnetic field. The phase diagram obtained from elastic constant measurements is compared with theoretical predictions.