Understanding the unusual-caged dynamics from the microstructure and interatomic interactions in binary metallic glass-forming liquids

The caged dynamics appears at time shorter than the β-relaxation but longer than the boson peak. Due to the limitations of experimental conditions, the mechanism of caged dynamics is not well studied in metallic glasses. We study a model La65Al35 glass-forming liquid with strong atomic interactions that presents an unusual caged dynamics, and the La65Ni35 GF liquid is also studied to clarify the underlying mechanisms of caged dynamics. There is a sudden drop near 0.1 ps in the partial non-Gaussian parameter of Al atoms, reflecting the development of caging of the Al atoms with time. A similar feature is also found in Ni80P20, Sm80Al20, Pd80Si20, and Y80Mg20 metallic GF liquids. The chemical order, Voronoi polyhedra, and covalent-like bonds are all related to the cage-breaking behavior of the central atoms, in turn regulating the unusual caged dynamics. These findings shed light on the complex relaxation dynamics of GF liquids.