Structural Origin of Boson Peak in Glasses
Abstract
Boson peak, the excess low energy excitations in the terahertz regime, is one of the most unique features of disordered systems and has been linked to many anomalous properties of glass materials. The nature and structural origin of the boson peak remain elusive and have been debated for more than a half century mainly due to the lack of real-time and real-space experimental insights of the dynamic phenomenon. In this work we employed femtosecond MeV ultrafast electron diffraction to characterize the atomic dynamics of metallic glasses in real time. The experiment reveals collective atomic oscillations, presented in elastic electron scattering and atomic pair distribution functions, within the boson peak frequency range of 1.0-1.8 THz in both reciprocal and real space. It was found that the oscillation frequency has reciprocal dependence on interatomic pair distances and the corresponding wave velocity experimentally affirms the transverse acoustic wave nature of the boson peak. The observed strong correlation between THz acoustic vibrations and coherent electron scattering provides compelling evidence that the boson peak originates from the collective transverse vibrational modes of structurally ordered atoms in the disordered system.
Keywords
Cite
@article{arxiv.2111.10171,
title = {Structural Origin of Boson Peak in Glasses},
author = {Yuan Tian and Xiaozhe Shen and Qingyang Gao and Zhen Lu and Jie Yang and Qiang Zheng and Christopher Florencio Aleman and Duan Luo and Alexander Hume Reid and Bin Xu and Michael Falk and Howard Sheng and Jianming Cao and Xijie Wang and Mingwei Chen},
journal= {arXiv preprint arXiv:2111.10171},
year = {2021}
}