The dynamical behavior of the normal fluid phase of liquid ${\mathrm{He}}^3$-${\mathrm{He}}^4$ mixtures near the tricritical point is studied. The superfluid order parameter and the entropy fluctuation are shown to have a common characteristic frequency which is the same as that predicted by dynamical scaling for the characteristic frequency of second sound in the ordered phase. The concentration fluctuation is shown to have a smaller characteristic frequency. The critical anomalies of the transport coefficients also are determined.

• Received 16 October 1972

DOI:https://doi.org/10.1103/PhysRevLett.29.1661