New evidence for zero-temperature relaxation in a spin-polarized Fermi liquid

Spin-echo experiments are reported for He3-He4 solutions under extremely high B/T conditions, B=14.75 T and T≥1.73 mK. The He3 concentration x3 was adjusted close to the value xc≅3.8% at which the spin-rotation parameter μM0 vanishes. In this way the transverse and longitudinal spin-diffusion coefficients were measured while keeping |μM0|<1. It is found that the temperature dependence of this coefficient deviates strongly from 1/T2, with anisotropy temperature Ta=4.26-0.44+0.18 mK. This value is close to the theoretical prediction for dilute solutions and suggests that spin current relaxation remains finite as the temperature tends to zero