MULTIPLE SPILL ECHOES DUE TO ANISOTROPIC SPILL DIFFUSION IN HE-3-HE-4SOLUTIONS

In a polarized Fermi fluid longitudinal and transverse spin diffusion constants will differ from one another below a temperature T-a. Althou gh Leggett-Rice effects are absent in degenerate spin-polarized He-3-H e-4 solutions at the He-3 concentration x(3) = 3.8%, analysis of the e quations of motion reveals that multiple spin echoes will still occur in theta(1) - t(1) - theta(2)-pulse NMR experiments due to the anisotr opy in the spin-diffusion coefficients, Delta D = D-parallel to - D-pe rpendicular to not equal 0. The absence of Leggett-Rice effects provid es a unique opportunity to observe the nonlinear dynamics introduced b y the anisotropy. It is shown that for temperatures below but near T-a , the second and third echo heights can be as much as 10% of the first echo.