Abstract
Nondiffusive phonon thermal transport, extensively observed in nanostructures, has largely been attributed to classical size effects, ignoring the wave nature of phonons. We report localization behavior in phonon heat conduction due to multiple scattering and interference events of broadband phonons, by measuring the thermal conductivities of GaAs/AlAs superlattices with ErAs nanodots randomly distributed at the interfaces. With an increasing number of superlattice periods, the measured thermal conductivities near room temperature increased and eventually saturated, indicating a transition from ballistic to diffusive transport. In contrast, at cryogenic temperatures the thermal conductivities first increased but then decreased, signaling phonon wave localization, as supported by atomistic Green’s function simulations. The discovery of phonon localization suggests a new path forward for engineering phonon thermal transport.
| Original language | English |
|---|---|
| Article number | eaat9460 |
| Journal | Science Advances |
| Volume | 4 |
| Issue number | 12 |
| DOIs | |
| State | Published - Dec 21 2018 |
Funding
We thank P. Sheng and Z. Zhang for the discussions. We also thank A. A. Maznev, K. A. Nelson, E. N. Wang, S. Huberman, V. Chiloyan, and L. Zeng. We acknowledge TEM Analysis Services Laboratory for the TEM images. Funding: Work at MIT was supported by the Solid-State Solar-Thermal Energy Conversion Center (S3TEC), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under award DE-SC0001299. Work at UCSB was supported by the Center for Energy Efficient Materials (CEEM), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under award DE-SC0001009. The low-frequency Raman spectra measurement was conducted at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. TEM work at BNL was supported by the U.S. Department of Energy, Office of Basic Energy Science, Division of Materials Science and Engineering, under contract no. DE-SC0012704. We acknowledge the support of the NIST, U.S. Department of Commerce, in providing the neutron research facilities used in this work. Identification of commercial products in this work does not imply recommendation or endorsement of those products by NIST.