Time reversal and the spin angular momentum of transverse-electric and transverse-magnetic surface modes

The polarization state of a surface mode is a hybrid between linear and elliptical states, meaning that although one of its electric- and magnetic-field components is linearly polarized, the other rotates on the transverse-longitudinal plane, effectively in its elliptical polarization state. We show that the rotation of the electric-field component can induce transverse spin angular momentum of the surface mode. The rotation of the magnetic-field component, however, cannot generate the spin. We argue that this results from the fact that the rotation direction of the magnetic field is invariant under time reversal.