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Propagating elastic vibrations dominate thermal conduction in amorphous silicon

Moon, Jaeyun and Latour, Benoit and Minnich, Austin J. (2018) Propagating elastic vibrations dominate thermal conduction in amorphous silicon. Physical Review B, 97 (2). Art. No. 024201. ISSN 2469-9950. doi:10.1103/PhysRevB.97.024201.

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The thermal atomic vibrations of amorphous solids can be distinguished by whether they propagate as elastic waves or do not propagate due to lack of atomic periodicity. In a-Si, prior works concluded that nonpropagating waves are the dominant contributors to heat transport, with propagating waves being restricted to frequencies less than a few THz and scattered by anharmonicity. Here, we present a lattice and molecular dynamics analysis of vibrations in a-Si that supports a qualitatively different picture in which propagating elastic waves dominate the thermal conduction and are scattered by local fluctuations of elastic modulus rather than anharmonicity. We explicitly demonstrate the propagating nature of waves up to around 10 THz, and further show that pseudoperiodic structures with homogeneous elastic properties exhibit a marked temperature dependence characteristic of anharmonic interactions. Our work suggests that most heat is carried by propagating elastic waves in a-Si and demonstrates that manipulating local elastic modulus variations is a promising route to realize amorphous materials with extreme thermal properties.

Item Type:Article
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URLURL TypeDescription Paper
Minnich, Austin J.0000-0002-9671-9540
Additional Information:© 2018 American Physical Society. Received 26 April 2017; revised manuscript received 15 December 2017; published 10 January 2018. This work was supported by the Samsung Scholarship, NSF CAREER Award No. CBET 1254213, and the Resnick Fellowship from the Resnick Sustainability Institute at Caltech.
Group:Resnick Sustainability Institute
Funding AgencyGrant Number
Samsung ScholarshipUNSPECIFIED
Resnick Sustainability InstituteUNSPECIFIED
Issue or Number:2
Record Number:CaltechAUTHORS:20170717-075759713
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:79119
Deposited By: Tony Diaz
Deposited On:17 Jul 2017 19:14
Last Modified:15 Nov 2021 17:45

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