Electrical and Magnetic Properties of Some Cubic Intermetallic Compounds of Plutonium with Ru, Rh, Ir, Pd, and Pt

The electrical resistivities and magnetic susceptibilities of the cubic intermetallic compounds of the form PuX₂ (X=Ru,0ex0exRh,0ex0exIr,0ex0exPt) and PuX₃ (X=Rh,0ex0exPd,0ex0exPt) have been measured from 2 to 300 ^∘{}K. The PuX₃ compounds order antiferromagnetically with N\'eel temperatures TN of 6.6, 24, and 40 ^∘{}K, respectively. The resistivities of the PuX₃ compounds decrease rapidly below TN, and there is also an abrupt change in the slope of the resistivity-versus-temperature curve at TN in PuRh₃. PuPt₂ orders ferromagnetically at a Curie temperature of TC=(6.0±0.3) ^∘{}K, and the resistivity falls dramatically below TC. PuRh₂ has a temperature-dependent susceptibility but there is no evidence for magnetic order, while the susceptibilites of PuRu₂ and PuIr₂ are temperature independent. However, the resistivities of PuRh₂, PuRu₂, and PuIr₂ have anomalous negative curvature at high temperatures, although the slopes remain positive throughout the temperature range investigated. The results are discussed in terms of the interatomic distance between plutonium atoms and the localized-spin-fluctuation model.