Interaction of Spin-Polarized Helium 2³S-Atoms with Ferromagnetic Surfaces

Abstract

In recent years numerous investigations of clean and adsorbate covered substrates have been carried out by different methods. As most investigations of electronic properties use methods which give information averaged over a depth of a few atomic layers, below the surface, there is, in comparison not so much knowledge about the electronic properties at the surface. A distinct surface sensitivity, however, can be achieved by electron emission caused by impact of metastable He(2³S)-atoms of thermal energy, a method called metastable deexcitation spectroscopy (MDS) (e.g. [1]). This technique probes predominantly the outermost atomic layer. The spin selective version of MDS uses an electron spin polarized He(2³S) atomic beam (SPMDS) and was experimentally pioneered at Rice University [2]. Using the spin selectivity in the deexcitation process (at the surface), one has an excellent tool for. obtaining information on the magnetic properties of the outermost region of the surface. Here we report on studies of electron emission from clean and oxygen covered iron (110) and cobalt (0001) films. Due to the high intensity of our atomic beam we are able to carry out angle and energy resolving SPMDS measurements. With our spectrometer the energy distribution of the emitted electrons is determined directly.