Date of this Version
J. Acoust. Soc. Am., Vol. 92, No. 4, Pt. 2, October 1992
Ultrasonic measurements on the heavy fermion superconductors have proved a useful tool in elucidating the nature of the superconfucting state. Earlier measurements of sound attenuation in superconducting UPt3 showed power-law temperature dependences (rather than an exponential temperature dependence as expected for a BCS type superconductor), indivating the presence of nodes in the gap. Subsequent ultrasonic measurements have shown indications of phase transitions within the superconducting state. In particular, these ultrasonic velocity measurements show the presence of three superconducting phases in the mixed state. The size of the velocity jump can be related to the heat capacity jump. Further, using a thermodynamic analysis it is possible to deduce the order of the phase transition lines.