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Dissipation induced by phonon elastic scattering in crystals

View Article: PubMed Central - PubMed

ABSTRACT

We demonstrate that the phonon elastic scattering leads to a dominant dissipation in crystals at low temperature. The two-level systems (TLSs) should be responsible for the elastic scattering, whereas the dissipation induced by static-point defects (SPDs) can not be neglected. One purpose of this work is to show how the energy splitting distribution of the TLS ensemble affects the dissipation. Besides, this article displays the proportion of phonon-TLS elastic scattering to total phonon dissipation. The coupling coefficient of phonon-SPD scattering and the constant P0 of the TLS distribution are important that we estimate their magnitudes in this paper. Our results is useful to understand the phonon dissipation mechanism, and give some clues to improve the performance of mechanical resonators, apply the desired defects, or reveal the atom configuration in lattice structure of disordered crystals.

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(a) A TLS including two stable states. Δ and Λ denote the separation and the tunneling between the upper state /u〉 and the lower one /d〉, respectively. (b) Four elastic scattering processes due to the TLSs. Each dashed arrow with kj indicates incident or released phonon with wave vector k and polarization j.
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f1: (a) A TLS including two stable states. Δ and Λ denote the separation and the tunneling between the upper state /u〉 and the lower one /d〉, respectively. (b) Four elastic scattering processes due to the TLSs. Each dashed arrow with kj indicates incident or released phonon with wave vector k and polarization j.

Mentions: According to the previous works282930, two-level systems (TLSs) have been suggested to exist in disordered part of crystals. Two parameters are needed to describe a TLS: the asymmetry Δ and the tunneling Λ between the two bound states (see Fig. 1(a)). The effective Hamiltonian of a TLS can be written as


Dissipation induced by phonon elastic scattering in crystals
(a) A TLS including two stable states. Δ and Λ denote the separation and the tunneling between the upper state /u〉 and the lower one /d〉, respectively. (b) Four elastic scattering processes due to the TLSs. Each dashed arrow with kj indicates incident or released phonon with wave vector k and polarization j.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036349&req=5

f1: (a) A TLS including two stable states. Δ and Λ denote the separation and the tunneling between the upper state /u〉 and the lower one /d〉, respectively. (b) Four elastic scattering processes due to the TLSs. Each dashed arrow with kj indicates incident or released phonon with wave vector k and polarization j.
Mentions: According to the previous works282930, two-level systems (TLSs) have been suggested to exist in disordered part of crystals. Two parameters are needed to describe a TLS: the asymmetry Δ and the tunneling Λ between the two bound states (see Fig. 1(a)). The effective Hamiltonian of a TLS can be written as

View Article: PubMed Central - PubMed

ABSTRACT

We demonstrate that the phonon elastic scattering leads to a dominant dissipation in crystals at low temperature. The two-level systems (TLSs) should be responsible for the elastic scattering, whereas the dissipation induced by static-point defects (SPDs) can not be neglected. One purpose of this work is to show how the energy splitting distribution of the TLS ensemble affects the dissipation. Besides, this article displays the proportion of phonon-TLS elastic scattering to total phonon dissipation. The coupling coefficient of phonon-SPD scattering and the constant P0 of the TLS distribution are important that we estimate their magnitudes in this paper. Our results is useful to understand the phonon dissipation mechanism, and give some clues to improve the performance of mechanical resonators, apply the desired defects, or reveal the atom configuration in lattice structure of disordered crystals.

No MeSH data available.


Related in: MedlinePlus