Valence fluctuation and electron–phonon coupling in La₆₈₋ₓCeₓAl₁₀Cu₂₀Co₂(x = 0, 34, and 68) metallic glasses

Abstract

We study the anomalous acoustic softening behavior in La₆₈₋ₓCeₓAl₁₀Cu₂₀Co₂(x=0, 34, and 68) metallic glasses by magnetic susceptibility, thermal expansion, and specific heat at low temperatures. The Ce-based metallic glass exhibits valence fluctuation phenomenon, anomalous thermal expansion and acoustic Grüneisen parameter at low temperatures. And we provide experimental evidence of the existence of strong electron–phonon coupling in the Ce-based metallic glasses by specific heat. The anomalous acoustic and thermal properties are attributed to the valence instability in the metallic glasses.