NONLINEAR LEGGETT-RICE EFFECT IN SPIN-POLARIZED SOLID HE-3

Spin diffusion involves the transport of the vector magnetisation, cha racterised by a diffusion tensor. A magnetic field destroys the system 's isotropy so that while longitudinal diffusion is real, transverse d iffusion becomes complex. The imaginary part leads to spin rotation si nce the spin current may no longer be parallel to the spin density. In spin polarised solid He-3 the molecular field of the exchange interac tion leads to such an effect, We have evaluated the elements of the di ffusion tensor to show this. A nonlinearity arises since the diffusion tensor so-calculated depends on the magnetisation. We show that this behaviour is described by the equation proposed by Leggett for phenome na in degenerate liquid He-3, Consequently the nonlinear phenomena in liquid He-3 have their analogues in the spin polarised solid.