Magnetic field control of polarized polariton condensates in rectangular microcavity pillars

The influence of a magnetic field on a spinor exciton polariton condensate has been investigated in rectangular GaAs microcavity pillars. The condensate has been found to demonstrate an elliptical polarization that changes with its density. The effect is attributed to the competition between the magnetic-field-induced circular polarization buildup and the spin-anisotropic polariton-polariton interaction which favors linear polarization resulting in a reduction of Zeeman splitting. The spin polarization of the condensate in rectangular pillars has been found to be close to equilibrium in contrast to that in planar microcavities that they are made of.