ELECTRICAL-RESISTIVITY OF PLUTONIUM MONOCHALCOGENIDES

Plutonium monochalcogenides show an almost temperature independent magnetization, while monopnictides are strongly magnetic. Since a divalent state is essentially excluded by the lattice parameters, the understanding of these compounds represents a great challenge. We report resistivity measurements performed on single crystals of PuS, PuSe and PuTe. The resistivity of all three chalcogenides is found to increase continuously from room temperature down to the lowest temperature with two changes of thermal behavior around 200 and 30 K. These compounds can be viewed as small gap semiconductors. We suggest that plutonium monochalcogenides are high-TK heavy fermions, their ground state being a weak magnetic nonconducting 6d1-5f5 Kondo state. © 1990.