Low-temperature spin diffusion in a spin-polarized Fermi gas.

We present a finite temperature calculation of the transverse spin-diffusion coefficient, D⊥, in a dilute degenerate Fermi gas in the presence of a small external magnetic field, H. While the longitudinal diffusion coefficient displays the conventional low-temperature Fermi-liquid behavior, D‖ ∝ T−2, the corresponding results for D⊥ show three separate regimes: (a) D⊥ ∼ H−2 for T ≪ H; (b) D⊥ ∼ T−2, D⊥/D‖ 6= 1 for T ≫ H and large spin-rotation parameter ξ ≫ 1, and (c) D⊥ = D‖ ∝ T−2 for T ≫ H and ξ ≪ 1. Our results are qualitatively consistent with the available experimental data in weakly spin-polarized 3He and 3He−4 He mixtures.