a flow in the x-direction of spins polarized along y is transformed to a flow in the y-direction of spins polarized along x. This prediction has yet not been confirmed experimentally. Optical monitoring The direct and inverse spin Hall effect can be monitored by optical means. The spin accumulation induces circular polarization of the emitted light, as well as the Faraday (or Kerr) polarization rotation of the transmitted (or reflected) light. Observing the polarization of emitted light allows the spin Hall effect to be observed. More recently, the existence of both direct and inverse effects was demonstrated not only in semiconductors, but also in metals. Applications The spin Hall effect can be used to manipulate electron spins electrically. For example, in combination with the electric stirring effect, the spin Hall effect leads to spin polarization in a localized conducting region. Further reading For a review of spin Hall effect, see for example: See also Quantum spin Hall effect References Hall effect Condensed matter physics Spintronics