Nature Phys. http://doi.org/bjmz (2016)

Credit: NATURE PUBLISHING GROUP

In the same way as charged electrons give rise to electric currents, electronic spins can generate spin currents. The latter could find applications in electronic devices with low power consumption, but controllable production of spin currents is a challenging task. Now, David Ellsworth and collaborators report the generation of a spin current across a non-magnetic metal thanks to a novel process termed photo-spin-voltaic (PSV) effect, observed in a structure composed of a platinum layer and an yttrium iron garnet film. Having applied a magnetic field to the iron garnet to produce a magnetization M in the film plane, the authors illuminated the heterostructure with a halogen light bulb placed on either the top or bottom side of the sample. The response of the resulting spin voltage Δμ to the direction of light illumination and to the orientation of the magnetic field indicated that the PSV effect is unrelated to light-induced temperature gradients, and that its origin is magnetic. Additional measurements, supported by theoretical calculations, pointed to the photon-driven spin-dependent excitation of the electrons in platinum atoms close to the iron garnet film as the mechanism responsible for the creation of a net spin current.