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Low temperature acoustic properties of amorphous silica and the Tunneling Model

EunJoo Thompson·G. Lawes·J. M. Parpia·R. O. Pohl
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Abstract

Internal friction and speed of sound of a-SiO(2) was measured above 6 mK using a torsional oscillator at 90 kHz, controlling for thermal decoupling, non-linear effects, and clamping losses. Strain amplitudes e(A) = 10^{-8} mark the transition between the linear and non-linear regime. In the linear regime, excellent agreement with the Tunneling Model was observed for both the internal friction and speed of sound, with a cut-off energy of E(min) = 6.6 mK. In the non-linear regime, two different behaviors were observed. Above 10 mK the behavior was typical for non-linear harmonic oscillators, while below 10 mK a different behavior was found. Its origin is not understood.

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EunJoo Thompson, G. Lawes, J. M. Parpia, R. O. Pohl. 1999-12-10. Low temperature acoustic properties of amorphous silica and the Tunneling Model. https://doi.org/10.1103/physrevlett.84.4601

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