Microwave surface impedance measurements on the heavy fermion superconductor UPt3

We have used cavity perturbation techniques to study the microwave surface impedance of the heavy fermion intermetalic compound UPt3 in the supercondu cting and normal states. The surface impedance as a function of temperature was measured in the frequency range from similar to 9 to 38 GHz. These mic rowave photon energies are about 20% to 95% of the estimated zero-temperatu re energy gap of UPt3. A change of slope was observed in the resistance vs. temperature curves at T-c. No evidence for a collective mode was observed for all the frequencies down to the lowest temperature reached(similar to 0 .1 K). (C) 1999 Elsevier Science B.V. All rights reserved.