High field dilatation experiments on U(Pt0.95Pd0.05)3; Magnetic ordering versus heavy fermion behaviour

A still open question is whether long-range magnetic ordering as observed in some heavy fermion (HF) systems is intimately related to the HF state or is an extra phenomenon interacting with it. This problem might be addressed by studying the compound U(Pt0.95Pd0.05)3. Doping UPt3 with 5% Pd induces long range antiferromagnetic order (LRAFO) which coexists with the heavy-fermion (HF) behavior. We present thermal expansion and magnetostriction data on U(Pt0.95Pd0.05)3 along all three crystallographic axes in magnetic fields (B parallel a-axis) up to 17T and the temperature range 1.5-12K covering the critical fields and temperatures of both the LRAFO (TN=5.8K, BAF=13T) and the HF state (T*∼8.2K, B*∼12T). We observe features related to the HF-behaviour and to the LRAFO separately, but also features which we interpret as originating from the interaction between LRAFO and HF-behaviour. ((orig.))