Pressure-induced americium valence fluctuations revealed by electrical resistivityA. V. Kolomiets1, J.-C. Griveau2, S. Heathman2, A. B. Shick3, F. Wastin2, P. Faure4, V. Klosek4, C. Genestier4, N. Baclet4 and L. Havela1
1 Charles University, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Ke Karlovu 5, 121 16 Prague 2, Czech Republic, EU
2 European Commission, Joint Research Centre, Institute for Transuranium Elements - Postfach 2340, D-76125 Karlsruhe, Germany, EU
3 Institute of Physics ASCR - Na Slovance 2, 182 21 Prague 8, Czech Republic, EU
4 Commissariat à l'Energie Atomique, CEA - Centre de Valduc - F-21120 Is-sur-Tille, France, EU
received 6 February 2008; accepted in final form 11 April 2008; published June 2008
published online 27 May 2008
Electrical resistivity of americium-plutonium fcc alloys was studied over a series of high-pressureinduced structural phase transitions accompanied by a volume collapse. The temperature dependence of resistivity flattens progressively in the high-pressure phases pointing to the presence of random strong scatterers at the Fermi energy. A theoretical analysis shows that this development is not related to the expected simple delocalization of Am 5f states. Instead it points to pressure-induced americium valence fluctuations (5f6-5f7), which provides a new microscopic basis for the understanding of transuranium materials on the verge of localization of the 5f electronic states.
75.30.Mb - Valence fluctuation, Kondo lattice, and heavy-fermion phenomena.
74.62.Fj - Pressure effects.
74.25.Fy - Transport properties (electric and thermal conductivity, thermoelectric effects, etc.).
© EPLA 2008