Anharmonic properties of vibrational excitations in amorphous solids
Anharmonic properties of vibrational excitations in amorphous solids
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DOI：
10.1103/physrevresearch.2.013215
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发表时间：
2019-11
影响因子：
4.2
通讯作者：
H. Mizuno;M. Shimada;A. Ikeda
中科院分区：
文献类型：
--
作者：
H. Mizuno;M. Shimada;A. Ikeda
了解非晶固体的振动和热性质是凝聚态物理学中讨论最多且长期存在的问题之一。最近的工作在理解谐波振动状态方面取得了重大进展。特别地，已经确定除了类声子振动模式之外还出现准定域振动模式。在这项工作中，我们研究了这些振动模式的非谐特性。我们发现振动模式表现出非和谐性，会引起粒子重新排列并导致向不同状态的转变。这些非谐性与晶体中的非谐性不同，晶体中永远不会发生粒子重排。值得注意的是，对于声子模式和准局域模式，振动模式都表现出很强的非谐性，并且引起的粒子重排总是在空间中局域化，并且由 1 到 1000 个粒子组成。我们的发现有助于理解低温热特性，其中非简谐振动至关重要。
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.