Phys. Rev. B 97, 235303 (2018)

For the realization of integrated spintronic devices, a spin-switching device is desired. Now, Alexis Askitopoulos and co-workers from the UK, Russia and Greece have experimentally observed that the two spin components of a polariton condensate can switch their orientation via illumination with light. A polariton condensate was generated in a high-quality (Q = 16,000) GaAs-based microcavity consisting of 10 nm GaAs quantum wells and a Rabi splitting of 9 meV. Light from a continuous-wave Ti:sapphire laser emitting at 754 nm was sent to the microcavity and the first excited state of the polariton condensate was optically trapped. The spin component of the condensate was investigated by means of polarization-resolved spectroscopy. When the excitation density of the light was increased from 12.48 mW to 14.56 mW, the dominant spinor state with a p-orbital symmetry was rotated by π/2. The phenomenon is explained by the spatially inhomogeneous depletion of the exciton reservoir and the repulsive exciton–polariton interaction. In principle, the approach could lead to a spin-demultiplexing device for polariton-based spin circuits.