We study the competition between the Kondo effect and frustrating exchange interactions in a Kondo-lattice model within a large-$\mathcal{N}$ dynamical mean-field theory. We find a $T=0\mathrm{}$ phase transition between a heavy Fermi liquid and a spin liquid for a critical value of the exchange $J_c{=T}_K^0$, the single-impurity Kondo temperature. Close to the critical point, the Fermi-liquid coherence scale $T^{\star }$ is strongly reduced and the effective mass strongly enhanced. The regime $T>\mathrm{}{T}^{\star }$ is characterized by spin-liquid magnetic correlations and non-Fermi-liquid properties. It is suggested that magnetic frustration is a general mechanism which is essential to explain the large effective mass of some metallic compounds such as ${\mathrm{LiV}}_2{\mathrm{O}}_4$.

• Received 7 February 2002

DOI:https://doi.org/10.1103/PhysRevB.66.045111