MRSej, Vol. 6, No.1, pp.213-222, 2004

ON THE SOUND PROPAGATION IN SILICA AEROGELS FILLED IN BY NORMAL AND SUPERFLUID HELIUM

D.A.Tayurskii1,2, K.Matsumoto2

1 Kazan State University , 420008 Kazan , Russia

2 Kanazawa University , Kanazawa , 920-1192, Japan

Earlier obtained experimental data concerning sound propagation in silica aerogels filled in by liquid 4He are theoretically analyzed for normal as well as superfluid phase. The simple phenomenological model is proposed for normal phase. The data for superfluid phase are described in a rather good manner by the hydrodynamic theory with taking into account the clamping of normal component by silica strands. It is shown also that at temperatures below 1 K one needs a new hydrodynamic theory in which momentum transfer between aerogel and phonons in liquid helium should be taken into account

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