Spin-Dependent Ion Scattering on Bismuth Surfaces

Abstract

We studied low-energy (∼1.5keV) spin-polarized ⁴He⁺ ion scattering on Bi(111) ultrathin films epitaxially grown on a Si(111) substrate. Even though Bi is a non-magnetic element, we observed that the scattered ion intensity differed between the incident He⁺ ions with up and down spins, i.e., a spin asymmetric scattering. The spin asymmetry was not affected by the surface structure but depended on the scattering angle and the incident energy. These data indicate that the spin asymmetry originates from the spin-orbit coupling that acts transiently on the He⁺ 1s electron spin in the binary collision and the resonant electron transfer between ⁴He⁺ ions and Bi electronic orbitals possibly alters the behavior of the spin asymmetry compared to established models.