Theory of Spin Relaxation by Magnetic Dipole Interaction in a Fermi Liquid: Application toHe3

We consider a system of fermions interacting via both strong spin-conserving and weak (spin-nonconserving) magnetic dipole forces. An expression for the spin relaxation rate $\frac{1}{T_1}$ in terms of the incoherent dynamic structure factor $S_I(q,\omega )$ is derived by treating the dipole interaction as a perturbation. We have calculated $T_1$ for normal liquid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ at all temperatures using the polarization-potential approach of Aldrich and Pines as well as the measured spin-diffusion coefficient and find good agreement with available data.