Spin-Polarized Photoelectrons from Fe, Co, and Ni

This experiment shows that photoelectrons from $3d$ ferromagnets exhibit a large spin polarization, which is in contrast to earlier investigations. The degree of polarization of electrons emitted from the neighborhood of the Fermi level was found to be + 54%, + 21%, and + 15% for Fe, Co, and Ni, respectively. The preferential direction of the magnetic moment is parallel to the magnetization, and this provides strong evidence against the applicability of the Stoner-Wohlfarth-Slater band theory for the interpretation of photoemission data. On introducing disorder in the lattice by depositing thin films onto cold substrates, the spin polarization decreases; for Fe and Ni the decrease scales with the number of Bohr magnetons per atom.