Spintronics: Taming spin currents

Versatile room-temperature control of spin currents without a net charge flow is making new inroads into the new methods to transfer and process information. Researchers chose spin pumping as an effective alternative way to generate spin currents. The spin and orbital motion are not independent and are coupled because the electron spin interacts with a relativistic magnetic field. Although the average speed of electrons is modest, individually they can move at relativistic speeds while they are scattered through the crystal that produces the spin-orbit coupling. The spin-orbit coupling leads to asymmetry in scattering exhibiting that the opposite spins moving in opposite directions are deflected towards the same edge of the region. As a result, the spin current yields a charge imbalance measured by a voltage. The spin-orbit coupling in a ferromagnet usually makes its lattice an efficient sink for the angular momentum carried by magnons.