We report the observation of the heavy-fermion behavior in the cerium-based bulk metallic glasses with an inherent strong structural disorder. The heavy-fermion behavior in the glasses with $4f$ electrons shows unique features not found in crystalline materials. The distribution of the $f$ levels due to structural disorder produces internal variation from the Kondo regime to the valence fluctuation regime, with the heavy-fermion behavior at the crossover. The glasses might provide a model system to investigate some longstanding issues with electron strong correlation in complex solids.

• Received 17 January 2007

DOI:https://doi.org/10.1103/PhysRevB.75.172201