We show theoretically that a weakly interacting gas of spin-polarized exciton-polaritons in a semiconductor microcavity supports propagation of spin waves. The spin waves are characterized by a parabolic dispersion at small wave vectors which is governed by the polariton-polariton interaction constant. Due to spin anisotropy of polariton-polariton interactions the dispersion of spin waves depends on the orientation of the total polariton spin. For the same reason, the frequency of homogeneous spin precession/polariton spin resonance depends on their polarization degree.

• Received 9 December 2014
• Revised 12 April 2015

DOI:https://doi.org/10.1103/PhysRevB.91.161307