Spin diffusion in a two-dimensional electron gas

Spin transport properties of spin-polarized two-dimensional electron systems are studied, with application to quantum wells or heterostructures of III-V semiconductors. We present numerical solutions of a quantum transport equation, which is a 2×2 matrix in spinor space. It is shown that the ``spin-rotation term,'' which leads to anomalous spin diffusion and spin waves in three-dimensional rarefied spin polarized ³He and Hydrogen, is also present in two-dimensional degenerate electron systems at low temperatures. Calculated longitudinal and transverse spin diffusion coefficients show different temperature dependence due to the fact that the phase space available in electron-electron scatterings associated with each diffusion process is different. We also discuss the possible experimental setups to achieve spin-polarized electrons in semiconductor quantum wells.