Relation between nanocluster approximation and Soft-Potential Model, the role of keystone nanocluster in the thermal conductivity

A plateau characterizes the thermal conductivity k( T) of many amorphous materials at temperatures above 1 K together with a maximum in specific heat C _p, called the Boson peak at the same temperature region. It has been believed for over 50 years that those features are the universal property of glasses. Using the analogy of the keystone species concept of ecology, where one species has a disproportionately large effect on its environment relative to its abundance, we will present the impact of keystone nanocluster concentration on low-temperature k( T). Our study is focused on the As-S glassy systems, where each compound represents a different environment. It is shown that the presence of keystone S ₈ nanoclusters leads to the plateau formation in the k( T) of As ₂S ₃ and As ₂S ₅ samples. At the same time, the Boson peak in the C _p was preserved, suggesting that nanoclusters contribute to both the k( T) plateau and C _p maximum.