Studies of paramagnetic metal surfaces and thin films using spin-sensitive electron spectroscopies

[摘要] Spin-sensitive electron spectroscopies were used to study paramagnetic metal surfaces and thin films. In these experiments, a beam of low-energy spin-polarized electrons from a GaAs source is directed at the target surface, and the spin polarizations and the energy distributions of scattered electrons are measured by a compact Mott polarimeter equipped with either a retarding field analyzer or a concentric hemispherical analyzer. Secondary electrons ejected from a Cu(100) surface by a polarized incident beam of energies 14, 50 and 100 eV were investigated by spin-polarized secondary electron spectroscopy. The data are interpreted in terms of the fractional contributions of rediffused primary and true secondary electrons to the total secondary electron yield. Spin-polarized electron-energy-loss spectra were obtained from Cu(100) and Mo(110). The data reveal strong evidence for inelastic spin-flip exchange scattering due to electron-hole pair excitation. In particular, a prominent polarization-loss feature evident in the Mo(110) data correlates with the joint density of occupied and unoccupied states. The dramatically different behavior in the polarization of scattered electrons from molybdenum and copper was employed as a signature to determine the attenuation length for low energy electrons in molybdenum. When molybdenum thin films were grown on a Cu(100) substrate, the Mo loss feature becomes prominent upon deposition of only one monolayer.

[发布机构] Rice University