A unique feature of exciton-polaritons, inherited from their mixed
light-matter origin, is the strongly spin-dependent polariton-polariton
interaction, which has been predicted to result in the formation of spin rings
in real space [Shelykh et al., Phys. Rev. Lett. 100, 116401 (2008)]. Here we
experimentally demonstrate the spin bi-stability of exciton-polaritons in an
InGaAs-based semiconductor microcavity under resonant optical pumping. We
observe the formation of spin rings whose size can be finely controlled in a
spatial scale down to the micrometer range, much smaller than the spot size. We
additionally evaluate the sign and magnitude of the antiparallel polariton spin
interaction constant.Comment: 5 pages, 4 figure
