2019/07/16 by Masanari Shimada, Hideyuki Mizuno, Atsushi Ikeda · 1 citation
Materials Science · Physics and Astronomy · #Elastic instability #Elasticity (physics) #Glass properties and applications #Instability #Material Dynamics and Properties #Nonlinear Photonic Systems #Normal mode #Quadratic equation #Quartic function #Vibration #Vibrational spectrum #cond-mat.dis-nn #cond-mat.soft
paper · pdf · doi:10.1039/d0sm00376j
9 pages, 1 figures
arxiv created 2019/07/16 · openalex created_date 2019/07/23 · openalex publication_date 2020/01/01 · arxiv updated 2020/08/14 · openalex updated_date 2026/08/05
The low-frequency vibrations of glasses are markedly different from those of crystals. These vibrations have recently been categorized into two types: spatially extended vibrations, whose vibrational density of states (vDOS) follows a non-Debye quadratic law, and quasilocalized vibrations (QLVs), whose vDOS follows a quartic law. The former are explained by elasticity theory with quenched disorder and microscopic replica theory as being a consequence of elastic instability, but the origin of the latter is still debated. Here, we show that the latter can also be directly derived from elasticity theory with quenched disorder. We find another elastic instability that the theory encompasses but that has been overlooked so far, namely, the instability of the system against a local dipolar force. This instability gives rise to an additional contribution to the vDOS, and the spatial structure and energetics of the mode originating from this instability are consistent with those of the QLVs. Finally, we construct a model in which the additional contribution to the vDOS follows a quartic law.