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Collision Drag Effect on Propagation of Sound in Liquid ${}^3$He in Aerogel

Takayuki Ichikawa·Mikio Ymamoto·Seiji Higashitani·Katsuhiko Nagai
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Abstract

Sound propagation in a Fermi liquid with impurities is studied using the Landau-Boltzmann equation and the result is compared with a recent experiment in liquid ${}^3$He in aerogel by Northwestern University group. The sound absorption calculated using the fixed impurity model is a few orders of magnitude larger than the experiment. We take into account the simultaneous motion of aerogel molecules and propose a model in which the momentum loss of ${}^3$He quasi-particles during the collisions with the aerogel is converted to a drag force that acts on the aerogel molecules. This collision drag model gives a reasonable description for the temperature and the pressure dependence of observed sound velocity and absorption.

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Takayuki Ichikawa, Mikio Ymamoto, Seiji Higashitani, Katsuhiko Nagai. 2001-07-31. Collision Drag Effect on Propagation of Sound in Liquid ${}^3$He in Aerogel. https://doi.org/10.1143/jpsj.70.3483

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