Fermi-Surface Measurements of Mixed-Valence CeSn3

The first measurements of Fermi-surface properties in a mixed-valence metal with use of the de Haas-van Alphen effect are presented. At least nine separate frequency branches in Ce${\mathrm{Sn}}_3$ are seen and effective masses as large as 9.2 have been measured. The experiments show that hybridization between the conduction states and local $f$ states occurs coherently in the mixed-valence compound Ce${\mathrm{Sn}}_3$, resulting in Bloch states with well-defined wave vector and energy.