Universal Features of Terahertz Absorption in Disordered Materials

TL;DR

This paper reveals a universal functional form for terahertz absorption in disordered materials, linking it to charge distributions and combining theory, experiments, and simulations.

Contribution

It introduces an analytical model demonstrating the universal frequency dependence of terahertz absorption in disordered materials.

Findings

The absorption coupling coefficient follows C(omega) = A + B*omega^2.

Constants A and B relate to charge distribution properties.

The universality holds across different disordered materials.

Abstract

Using an analytical theory, experimental terahertz time-domain spectroscopy data and numerical evidence, we demonstrate that the frequency dependence of the absorption coupling coefficient between far-infrared photons and atomic vibrations in disordered materials has the universal functional form, C(omega) = A + B*omega^2, where the material-specific constants A and B are related to the distributions of fluctuating charges obeying global and local charge neutrality, respectively.