SPECIFIC-HEAT AND MAGNETIC-SUSCEPTIBILITY OF UPT3 AND UBE13 AT MK-TEMPERATURES

We have measured the specific heat capacity of a single crystal of UPt 3 in zero magnetic field, in 2 T, and in 4 T (above B-c2) With the adi abatic warm-up method down to a final temperature of 15 mK. The result s prove our previous assumption that the normal state of UPt3 exhibits a similar, slightly modified specific heat anomaly around 20 mK as is present in the superconducting state. It is most probably a signature of long range magnetic order. Entropy balance above T-c is fulfilled if both low-temperature peaks are included. For UBe13 (in the supercon ducting state) we find no specific heat anomaly down to 24 mK but a de viation from the power law valid at higher temperatures. DC-magnetizat ion measurements on a second single crystal of UPt3 in a SQUID system yield a temperature dependence similar to T-2 between 150 and 20 mK ex tending the temperature range of earlier measurements by a factor of 4 .