Spin-dependent low-energy $^4$He$^+$ ion scattering on non-magnetic surfaces

We investigated electron-spin-polarized $^4$He$^+$ ion scattering on various non-magnetic surfaces at kinetic energies below 2 keV [1]. It was observed that the scattered He$^+$ ion yield depends on the He$^+$ ion spin. We interpret this spin-dependent scattering in terms of the spin-orbit coupling (SOC) that acts transiently on the He$^+ 1s$ electron spin in the He$^+$-target binary collision. This interpretation qualitatively explains the relationship between the spin-dependent scattering and the scattering geometry, incident velocity, and magnetic field arrangement. This is the first study to report SOC caused by projectile electron spin in ion scattering.\\[4pt] [1] T.Suzuki, Y.Yamauchi, and S.Hishita, Phys.Rev.Lett. 107(2011)176101.