Electron-Spin Dependent Surface Scattering of a Polarized 4 He + Ion Beam

Abstract

An electron-spin polarized He ion beam is useful for analyzing the spin polarization on outermost surfaces (spinpolarized ion scattering spectroscopy). This is because the neutralization of the He ion (the Auger neutralization) in the vicinity of the surface is dependent on the spin due to the Pauli principle. Thus, the element-selective spin polarization of the outermost surface is analyzed from the spin-dependent ion scattering (the spin asymmetry). We recently found that the spin asymmetry also appears on the surface of a non-magnetic material. The appearance of the spin asymmetry is quantitatively interpreted in terms of the anomalously large spin-orbit coupling (SOC) in the quantum mechanical intermediate state, where the SOC transiently acts on the spin of the virtually created hole in the target during the He ion-target atom binary collision.