Abstract
Polaritons are hybrid light–matter quasiparticles arising from the strong coupling of excitons and photons. Owing to the spin degree-of-freedom, polaritons form spinor fluids able to propagate in the cavity plane over long distances with promising properties for spintronics applications. Here we demonstrate experimentally the full control of the polarization dynamics of a propagating exciton–polariton condensate in a planar microcavity by using a magnetic field applied in the Voigt geometry. We show the change of the spin-beat frequency, the suppression of the optical spin Hall effect, and the rotation of the polarization pattern by the magnetic field. The observed effects are theoretically reproduced by a phenomenological model based on microscopic consideration of exciton–photon coupling in a microcavity accounting for the magneto-induced mixing of exciton–polariton and dark, spin-forbidden exciton states.
Highlights
Polaritons are hybrid light–matter quasiparticles arising from the strong coupling of excitons and photons
The remarkable progresses in the control of matter–light interaction in semiconductor optical microcavities have made it possible to design a new generation of optoelectronic devices[1,2,3,4,5,6,7]. These are based on the peculiar properties of exciton-polaritons, half-light half-matter bosonic quasiparticles arising from the strong coupling between photonic cavity modes and excitons in quantum wells placed inside the cavity
One of the most remarkable properties of polaritons is that they have a spin degree of freedom inherited from the photon chirality and exciton spin angular momentum that shows long coherence time and the possibility to be actively manipulated by external fields through the excitonic component[8,9]
Summary
Polaritons are hybrid light–matter quasiparticles arising from the strong coupling of excitons and photons. In this study we demonstrate that this is not the case by showing that an in-plane magnetic field increases (decreases) the effect of the intrinsic LT splitting ΩLT when applied perpendicularly (parallel) to the propagation direction of polaritons
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