Watching Spin Currents

Future spintronic circuits will use the spin orientation of an electron current to store and manipulate information. Such spin-polarized currents, however, cannot be directly observed and are typically characterized using indirect techniques. Zi Qiu at the University of California, Berkeley, and colleagues have now demonstrated that x-ray pulses from a synchrotron source can be used to measure the precession of spins in a material, which directly reveals the flow of a spin current. The technique allowed the researchers to observe a spin current as it propagated through different layers of materials.