Local structure and superconductivity of theCe1−xLaxRu2Laves phase system

We have studied local structure of the Laves phase Ce{sub 1-x}La{sub x}Ru{sub 2} superconductor by Ru K-edge extended x-ray absorption fine-structure measurements focusing on the small La concentration regime where the transition temperature T{sub c} passes through a local maximum. We find that correlated Debye-Waller factor of the Ru-Ru bonds follows T{sub c} with the varying La concentration in the system. Although, this remarkable T{sub c} correlation on the local atomic structure suggests important role of the electron-lattice interactions, the band-structure effects seem more likely the reason to drive the anomalous superconducting behavior and the T{sub c} maximum in this 4f system.