Spin diffusion and oscillations of the magnetization at high-frequency spin injection

The frequency dependence of the nonequilibrium magnetization arising in an electron gas due to spin injection from a half-metallic ferromagnet into a nonmagnetic material is theoretically analyzed. It is shown that high-frequency spin injection gives rise to nonequilibrium magnetization waves, which decay at a length much smaller than the spin diffusion length. This reduces the efficiency of spin injection.