Tricritical Slowing Down of Phase Separation in LiquidHe3-He4Mixtures

Measurements of the dynamics of phase separation in homogeneous mixtures of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ have been performed at temperatures ranging from 17 mK to within 3 mK of the tricritical temperature. The results are the first to show the expected critical slowing down of the dynamics proportional to $\epsilon$ as the tricritical point is approached.