Liquid-like clusters in glassy solids as a unique state of matter: Dissipative but non-diffusive

The field of glassy studies has long speculated about the existence of liquid-like regions within solid amorphous states. However, limited evidence from indirect investigations has left the question of their presence unanswered. In this study, we propose a computational approach to analyze dissipation characteristics at the atomic level. Our findings reveal the actual existence of localized liquid-like dissipation clusters in the glassy state, demonstrating a damping factor similar to liquids and a vanishing shear modulus. Surprisingly, these clusters are only observed at low temperatures and do not involve diffusive motions, unlike typical liquids. This unique state of condensed matter is dissipative but non-diffusive. In metallic glasses, we show that these clusters are responsible for the recently discovered β' relaxation. Our results provide a solid basis for the longstanding concept of liquid-like region in glassy materials and provide a new perspective on establishing structure-property correlations.