Network rigidity and dynamics of oxides
Abstract
If a hierarchy of interatomic interactions exists in a solid, low-frequency modes can be found from viewing this solid as a mechanical network. In this case, the low-frequency modes are determined by the network rigidity. We study the low-frequency modes (rigid unit modes, or RUMs) in several important oxide materials and discuss how the RUMs affect their properties. In SiO glass, the ability to support RUMs governs its relaxation in the wide range of pressures and temperatures, giving rise to the non-trivial pressure window. It also affects other properties, including crystallization, slow relaxation and compressibility. At ambient pressure and low temperature, RUM flexibility is related to the large-scale localized atomic motions. Whether these motions are interpreted as independent two-level systems or collective density excitations, the RUM flexibility determines whether and to what extent low-energy excitations can exist in a given glass structure. Finally, we discuss the RUM in, perhaps unexpectedly, cuprate superconductors, and its relevance for superconductivity, including the d-wave symmetry of the order parameter and other properties.
Cite
@article{arxiv.0805.1392,
title = {Network rigidity and dynamics of oxides},
author = {Kostya Trachenko and Martin T Dove},
journal= {arXiv preprint arXiv:0805.1392},
year = {2008}
}