论文标题
无定形材料中声子 - 两极的物理
Physics of Phonon-Polaritons in Amorphous Materials
论文作者
论文摘要
由于困难在存在障碍的情况下定义诸如准颗粒之类的关键概念，因此无序材料中骨气激发的性质仍然难以捉摸。我们报告了玻璃中声子 - 两极的实验观察，包括玻色子峰（BP），即超过Debye定律的THZ模式过多。开发了基于扩散概念的理论框架是为了模拟由于疾病诱导的散射而建模了极化的宽阔线宽。结果表明，线宽的扩散常数的缩放频率与极化子的Ioffe-Regel（ir）交叉频率的扩散常数密切相关。该结果证明了BP在玻璃杯中类似玻璃体的刺激的低能光谱中的普遍性，远远超出了传统的声音声子，并确定了IR交叉作为BP背后的基本物理机制。
The nature of bosonic excitations in disordered materials has remained elusive due to the difficulties in defining key concepts such as quasi-particles in the presence of disorder. We report on the experimental observation of phonon-polaritons in glasses, including a boson peak (BP), i.e. excess of THz modes over the Debye law. A theoretical framework based on the concept of diffusons is developed to model the broadening linewidth of the polariton due to disorder-induced scattering. It is shown that the scaling of the BP frequency with the diffusion constant of the linewidth strongly correlates with that of the Ioffe-Regel (IR) crossover frequency of the polariton. This result demonstrates the universality of the BP in the low-energy spectra of collective bosonic-like excitations in glasses, well beyond the traditional case of acoustic phonons, and establishes the IR crossover as the fundamental physical mechanism behind the BP.
