Connected Network Model for the Mechanical Loss of Amorphous Materials

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Hauptverfasser: Blaber, Steven, Bruns, Daniel, Rottler, Jörg
Format: Preprint
Veröffentlicht: 2024
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author Blaber, Steven
Bruns, Daniel
Rottler, Jörg
author_facet Blaber, Steven
Bruns, Daniel
Rottler, Jörg
contents Dissipation in amorphous solids at low frequencies is commonly attributed to activated transitions of isolated two-level systems (TLS) that come in resonance with elastic or electric fields. Materials with low mechanical or dielectric loss are urgently needed for applications in gravitational wave detection, high precision sensors, and quantum computing. Using atomistic modeling, we explore the energy landscape of amorphous silicon and titanium dioxide, and find that the pairs of energy minima that constitute single TLS form a sparsely connected network with complex topologies. Motivated by this observation, we develop an analytically tractable theory for mechanical loss of the full network from a nonequilibrium thermodynamic perspective. We demonstrate that the connectivity of the network introduces new mechanisms that can both reduce low frequency dissipation through additional low energy relaxation pathways, and increase dissipation through a broad distribution of energy minima. As a result, the connected network model predicts mechanical loss with distinct frequency profiles compared to the isolated TLS model. This not only calls into question the validity of the TLS model, but also gives us many new avenues and properties to analyze for the targeted design of low mechanical loss materials.
format Preprint
id arxiv_https___arxiv_org_abs_2406_17978
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Connected Network Model for the Mechanical Loss of Amorphous Materials
Blaber, Steven
Bruns, Daniel
Rottler, Jörg
Materials Science
Statistical Mechanics
Dissipation in amorphous solids at low frequencies is commonly attributed to activated transitions of isolated two-level systems (TLS) that come in resonance with elastic or electric fields. Materials with low mechanical or dielectric loss are urgently needed for applications in gravitational wave detection, high precision sensors, and quantum computing. Using atomistic modeling, we explore the energy landscape of amorphous silicon and titanium dioxide, and find that the pairs of energy minima that constitute single TLS form a sparsely connected network with complex topologies. Motivated by this observation, we develop an analytically tractable theory for mechanical loss of the full network from a nonequilibrium thermodynamic perspective. We demonstrate that the connectivity of the network introduces new mechanisms that can both reduce low frequency dissipation through additional low energy relaxation pathways, and increase dissipation through a broad distribution of energy minima. As a result, the connected network model predicts mechanical loss with distinct frequency profiles compared to the isolated TLS model. This not only calls into question the validity of the TLS model, but also gives us many new avenues and properties to analyze for the targeted design of low mechanical loss materials.
title Connected Network Model for the Mechanical Loss of Amorphous Materials
topic Materials Science
Statistical Mechanics
url https://arxiv.org/abs/2406.17978