Role of Conduction Electrons in Valence Fluctuations

We report magnetic susceptibility results for the valence fluctuation system $\mathrm{Ce}{\mathrm{In}}_{3-x}{\mathrm{Sn}}_x$. In the intermediate-valence regime the characteristic energy of spin fluctuations does not vary monotonically with solute $\frac{e}{a}$ ratio, but oscillates with $x$ in the same manner as the conduction-electron density of states. This provides experimental evidence for the role played by the conduction electrons in controlling the spin fluctuation energy.