Relating structural heterogeneity to β relaxation processes in metallic glasses

The β relaxation is a crucial feature in metallic glasses (MGs). However, its structural origin is not fully elucidated. Using a contact resonance atomic force microscope, we investigated the local structural heterogeneity of MGs and its correlation with β relaxations. It was found that MGs have various degrees of the heterogeneity, resulting in different intensities of β relaxations. Local zones with a prominent heterogeneity lead to a broad energy state distribution and more pronounced β relaxation. Our results provide a direct experimental evidence to clarify the mechanism of the β relaxations, suggesting a guideline for controlling β relaxations of MGs.