Minimizing Coherent Thermal Conductance by Controlling the Periodicity of Two-Dimensional Phononic Crystals
Abstract
Periodic hole-array phononic crystals (PnCs) can strongly modify phonon dispersion relations and have been shown to influence thermal conductance coherently, especially at low temperatures where bulk scattering is suppressed. One very important parameter influencing this effect is the period of the structure. Here, we measure the subkelvin thermal conductance of nanofabricated PnCs with identical hole-filling factors but three different periodicities, of 4, 8, and 16μm, using superconducting tunnel-junction thermometry. We find that all the measured samples can suppress thermal conductance by an order of magnitude and have a lower thermal conductance than the previously measured smaller-period 1-μm and 2.4-μm structures. The 8-μm-period PnC gives the lowest thermal conductance of all the above samples and has the lowest specific conductance per unit heater length observed to date in PnCs. In contrast, coherent transport theory predicts that the longest period should have the lowest thermal conductance. Comparison with incoherent simulations suggests that diffusive boundary scattering is likely the mechanism behind the partial breakdown of the coherent theory.
Main Authors
Format
Articles
Research article
Published
2019
Series
Subjects
Publication in research information system
Publisher
American Physical Society
The permanent address of the publication
https://urn.fi/URN:NBN:fi:jyu-201907303718Use this for linking
Review status
Peer reviewed
ISSN
2331-7019
DOI
https://doi.org/10.1103/physrevapplied.12.014008
Language
English
Published in
Physical Review Applied
Citation
- Tian, Y., Puurtinen, T. A., Geng, Z., & Maasilta, I. J. (2019). Minimizing Coherent Thermal Conductance by Controlling the Periodicity of Two-Dimensional Phononic Crystals. Physical Review Applied, 12(1), Article 014008. https://doi.org/10.1103/physrevapplied.12.014008
Funder(s)
Research Council of Finland
Funding program(s)
Academy Project, AoF
Akatemiahanke, SA

Additional information about funding
This study was supported by the Academy of Finland Project Number 298667 and the China Scholarship Council. We thank C. Dames and G. Wehmeyer for sharing the Monte Carlo code. The computational facilities provided
by the CSC-IT Center for Science Ltd. are acknowledged.
Copyright© 2019 American Physical Society