Spin entropy wave propagation in magnetically polarized superfluid 3He

The Spin-Entropy Wave (SEW) is the second sound (normal-superfluid counterflow mode) propagation in the spin-polarized superfluid He-3 A(1) phase. Measurement of the propagation velocity gives the anisotropy components of the superfluid fraction. The perpendicular anisotropy component of superfluid density is measured as a junction of magnetic,field up to 12 T at 21.5 bar The attenuation in bulk A, fluid is measured and is compared with theory on the spin diffusion and other dissipative coefficients. An anomalous diverging attenuation is observed at the lower transition temperature of the A(1) phase. When the superfluid flow accompanying the SEW is directed parallel to the anisotropy 1 texture, the flow field distorts the texture. The distortion results in an unusual non-linear propagation phenomena in which the non-linearity is greatest at intermediate flow velocities but reverts hack to linear propagation at larger flow velocities. A mechanical system of mass attached to a "soft" spring is developed to model the non-linear propagation. An experiment is devised to control the (l) over cap texture with one SEW resonance mode and to measure the texture transformation with an independent mode in a rectangular cell. Evidence for first order transitions of (l) over cap texture is presented.