The microscopic details of the suppression of antiferromagnetic order in the Kondo-lattice series ${\mathrm{Ce}}_{1-x}{\mathrm{La}}_x{\mathrm{Cu}}_2{\mathrm{Ge}}_2$ due to nonmagnetic dilution by La are revealed through neutron diffraction results for $x=0.20$, 0.40, 0.75, and 0.85. Magnetic Bragg peaks are found for $0.20\le x\le 0.75$, and both the Néel temperature $T_{\mathrm{N}}$ and the ordered magnetic moment per Ce $\mu$ linearly decrease with increasing $x$. The reduction in $\mu$ points to strong hybridization of the increasingly diluted Ce $4f$ electrons, and we find a remarkable quadratic dependence of $\mu$ on the Kondo-coherence temperature. We discuss our results in terms of local-moment- versus itinerant-type magnetism and mean-field theory and show that ${\mathrm{Ce}}_{1-x}{\mathrm{La}}_x{\mathrm{Cu}}_2{\mathrm{Ge}}_2$ provides an exceptional opportunity to quantitatively study the multiple magnetic interactions in a Kondo lattice.

• Received 23 October 2017
• Revised 3 April 2018

DOI:https://doi.org/10.1103/PhysRevB.97.165121