Cubic-to-Tetragonal Transformation and Susceptibility inLaAgxIn1−xAlloys

The magnetic susceptibility $\chi \mathrm{}(x,T)\mathrm{}$ of the pseudobinary intermetallic compound $\mathrm{La}{\mathrm{Ag}}_x{\mathrm{In}}_{1-x}$ is given for temperatures $T$ between 20 and 250 K with $x$ between 1.0 and 0.15. For $x$ between 0.9 and 0.6, $\chi$ is very anomalous, rising strongly as the samples are cooled until a temperature $T_M\mathrm{}\left(x\right)\mathrm{}$ is reached where a cubic-to-tetragonal crystallographic transformation is found to occur and the susceptibility drops to a much lower value. The transformation is shown to arise from a band Jahn-Teller effect. The behavior of $\chi \mathrm{}(x,T)\mathrm{}$ as well as $T_M\mathrm{}\left(x\right)\mathrm{}$ can be described quantitatively over a broad range of $x$ assuming that the Fermi energy of LaAg lies closely below a high peak in the density of states which originates from the $e_g$ states of La. This peak becomes gradually populated as the electron concentration is increased by replacing Ag by In.