Realization of a room-temperature spin dynamo: the spin rectification effect.

We demonstrate a room-temperature spin dynamo where the precession of electron spins in ferromagnets converts energy from microwaves to a bipolar current of electricity. The current/power ratio is at least 3 orders of magnitude larger than that found previously for spin-driven currents in semiconductors. The observed bipolar nature and intriguing symmetry are fully explained by the spin rectification effect via which the nonlinear combination of spin and charge dynamics creates dc currents.