Optical selection rules in spin–orbit coupled systems on honeycomb lattice

We investigate the optical properties in a minimal model of spin–orbit coupled systems on honeycomb lattice at half-filling. In particular, the absorption of circularly polarized light in the charge and antiferromagnetic ordered states is studied, and spin-valley selective excitation depending on the handedness of the light is found. It is shown that the optical selection rules plainly differ according to the type of broken symmetries and topological properties of the electronic states. Consequently, the spin-valley selectivity in optical absorption abruptly changes at the topological transition caused by the change of magnitude of the order parameters.