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Prediction and observation of intermodulation sidebands from anharmonic phonons in NaBr

Shen, Y. and Saunders, C. N. and Bernal, C. M. and Abernathy, D. L. and Williams, T. J. and Manley, M. E. and Fultz, B. (2021) Prediction and observation of intermodulation sidebands from anharmonic phonons in NaBr. Physical Review B, 103 (13). Art. No. 134302. ISSN 2469-9950. doi:10.1103/physrevb.103.134302.

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A quantum Langevin model, like models from optomechanics, was developed for phonons. It predicts intermodulation phonon sidebands (IPSs) in anharmonic crystals. Ab initio calculations of anharmonic phonons in rock-salt NaBr showed these spectral features as many-body effects. Modern inelastic neutron scattering measurements on a crystal of NaBr at 300 K revealed diffuse intensity at high phonon energy from a predicted upper IPS. The transverse optical (TO) part of the new features originates from phonon intermodulation between the transverse acoustic (TA) and TO phonons. The longitudinal optical spectral features originate from three-phonon coupling between the TA modes and the TO lattice modes. The partner lower IPS proves to be an intrinsic localized mode. Interactions with the thermal bath broaden and redistribute the spectral weight of the IPS pair. These sidebands are a probe of the anharmonicity and quantum noise of phonons in NaBr and suggest novel interactions between photons and phonons.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Saunders, C. N.0000-0001-7973-3722
Bernal, C. M.0000-0001-7550-3153
Abernathy, D. L.0000-0002-3533-003X
Manley, M. E.0000-0003-4053-9986
Fultz, B.0000-0002-6364-8782
Alternate Title:Prediction and Observation of Intermodulation Sidebands from Anharmonic Phonons
Additional Information:© 2021 American Physical Society. Received 14 November 2020; accepted 16 March 2021; published 12 April 2021. We thank O. Hellman, K. Vahala, and F. Yang for helpful discussions. Research at the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory was sponsored by the Scientific User Facilities Division, Basic Energy Sciences (BES), Department of Energy (DOE). M.E.M. was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division under Contract No. DE-AC05-00OR22725. This paper used resources from National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science User Facility supported by the Office of Science of the US Department of Energy under Contract No. DE-AC02-05CH11231. This paper was supported by the DOE Office of Science, BES, under Contract No. DE-FG02-03ER46055.
Funding AgencyGrant Number
Department of Energy (DOE)DE-AC05-00OR22725
Department of Energy (DOE)DE-AC02-05CH11231
Department of Energy (DOE)DE-FG02-03ER46055
Issue or Number:13
Record Number:CaltechAUTHORS:20210421-095643731
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108782
Deposited By: Tony Diaz
Deposited On:21 Apr 2021 19:22
Last Modified:21 Apr 2021 19:22

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