Spin-splitting in a reflective beam off an antiferromagnetic surface

A linearly-polarized radiation can be considered as the superposition of two circularlypolarized components with the same propagating direction and opposite spins. We investigated the splitting between the two spin-components in the reflective beam off the antiferromagnetic surface. The gyromagnetism and surface impedance mismatch cause the difference between the spatial shifts of the two spin-components, i.e., the spin-splitting. We analytically achieved the in- and out-plane shift-expressions of either spin-component for two typical linearly-polarized incident beams (i.e., the p- and s-incidences). In the case of no gyromagnetism, we obtained very simple shift-expressions, which indicate a key role played by the gyromagnetism or the surface impedance-mismatch in spin-splitting. Based on a FeF2 crystal, the spin-splitting distance was calculated. The spin-splitting distance is much longer for the p-incidence than the s-incidence, and meanwhile the in-plane splitting distance is much larger than the out-plane one. The gyromagnetism plays a key role for the in-plane spin-splitting and the surface impedancemismatch is a crucial factor for the out-plane spin-splitting distance. The results are useful for the manipulation of infrared radiations and infrared optical detection. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement