T-3 temperature dependence and a length scale for the thermal boundary resistance between a saturated dilute 3He-4He solution and sintered silver.

Abstract

We have measured the thermal boundary resistance between various configurations of sintered silver and a saturated $^{3}\mathrm{He}$-$^{4}\mathrm{He}$ solution between 8 and 150 mK. We observe that there is a length scale involved in the heat flow between sinter and liquid, which manifests itself as a thickness-dependent crossover from a ${T}^{\ensuremath{-}1.5}$ dependence of the resistance at high temperatures to a ${T}^{\ensuremath{-}3}$ behavior at low temperatures. This allows us to extract the Kapitza boundary resistance which we find to vary as ${T}^{\ensuremath{-}3}$, as expected from simple theory, and not as ${T}^{\ensuremath{-}2}$ as suggested by most recent measurements.