Effects of the Electronic Spin-Orbit Interaction on the Anomalous Asymmetric Scattering of the Spin-Polarized He-4(+) Beam with Paramagnetic Target Materials

摘要

The scattering of the electron-spin-polarized He-4(+) beam on paramagnetic materials has an anomalously large asymmetric scattering component (ASC) around 5%, which is 10(4) of that expected from the spin-orbit coupling (SOC) for the potential of the target nucleus. In addition, the ASC of some materials (for example, Au and Pt) changes sign near the scattering angle (theta) of 90 degrees unlike the result predicted by using the potential scattering theory. When the 4He+ approaches the target, virtual electron-transfer (ET) excitations between them occur. The effects of the SOC of electrons (SOEs) on the target atom in the ET intermediate state are studied within the frame of the lowest-order perturbation theory about the ET process. The ASC is caused through the combination of the quantum development of electron orbital states under the SOEs and the He nucleus motion in the intermediate state because the preferred orbital states for the ET depend on the position of the He nucleus. It is shown by a numerical calculation that the present process has the possibility of producing the ASC with a magnitude of around 0.1. In the present process, the ASC shows a. dependence of cos theta sin theta, which changes sign at theta = 90 degrees when the excited orbital in the ET state has the d-character like the Au and Pt cases.