Appl. Phys. Lett., 101, 171103 (2012)

The spin Hall effect of light (SHEL) is the photonic analogue of the spin Hall effect in electronic systems, in which the electron spin and role of an applied electric field are replaced by the polarization of an incident light wave and the refractive index gradient of the sample material, respectively. The SHEL can be observed as a displacement of optical beams that carry angular momenta. Jinli Ren and co-workers from Peking University in China now report that the complex refractive index of a magnetic medium strongly affects the SHEL. The researchers irradiated a 100-nm-thick cobalt film on a glass substrate with a red (632.8 nm) HeNe laser beam. They measured the SHEL displacement as a function of the incident angle for the two electric field polarizations: parallel (P-polarization) and perpendicular (S-polarization) to the plane of incidence. The maximum displacements were 10 nm for P-polarization and 20 nm for S-polarization. However, these values were smaller than those expected from numerical simulations for an air–cobalt interface. The researchers therefore calculated the effective complex refractive indices by considering the thickness of the cobalt film, and found that the real part of the complex refractive index strongly affects the displacement for P-polarization, whereas the imaginary part strongly affects that for S-polarization.