THEORY OF SPIN POLARIZATION IN THE METASTABLE-HE METAL INTERACTION

In a recent experiment by Hart et al., the spin polarization of electrons emitted in the interaction between metastable He and Cu was measured as a function of their kinetic energy. The polarization was found to increase with increasing electron energy from approximately 22% at the lowest energy to around 75% at the highest energy. The purpose of the present work is to show the crucial role played by three factors: the exchange interaction in Auger neutralization, secondary electrons, and Auger deexcitation. With these, we explain why there is a measured spin polarization and why the spin polarization increases with increasing kinetic energy of the ejected electrons. Using a simple model for the copper wave functions and including surface screening, our calculation shows a good agreement with the experimental results.