Anharmonic properties of vibrational excitations in amorphous solids

Abstract

Understanding the vibrational and thermal properties of amorphous solids is one of the most discussed and long-standing issues in condensed matter physics. Recent works have made significant steps towards understanding harmonic vibrational states. In particular, it has been established that quasi-localized vibrational modes emerge in addition to phonon-like vibrational modes. In this work, we study the anharmonic properties of these vibrational modes. We find that vibrational modes exhibit anharmonicities that induce particle rearrangements and cause transitions to different states. These anharmonicities are distinct from those in crystals, where particle rearrangements never occur. Remarkably, for both the phonon modes and quasi-localized modes, the vibrational modes exhibit strong anharmonicities, and the induced particle rearrangements are always localized in space and are composed of 1 to 1000 particles. Our findings contribute to the understanding of low-temperature thermal properties, for which anharmonic vibrations are crucial.

14 pages, 14 figures, 1 table

References in corpus (6)

• Suppression of tunneling two-level systems in ultrastable glasses of indomethacin
• Dynamic criticality at the jamming transition
• Two-Level Systems and Boson Peak Remain Stable in 110-Million-Year-Old Amber Glass
• Acoustic excitations and elastic heterogeneities in disordered solids
• Nonlinear modes disentangle glassy and Goldstone modes in structural glasses
• Boson peak dynamics of glassy glucose studied by integrated terahertz-band spectroscopy