Specific-heat anomaly in superconductingUPt3at 18 mK

Abstract
We have observed large specific-heat anomalies around 18 mK in two single-crystal samples of UPt3 of different origin. These indicate additional forms of order which still take place in the electronic system of the heavy-fermion compound at these low temperatures. Since magnetic-susceptibility measurements showed that the samples remain superconducting, the new ordering coexists with superconductivity.