Strong itinerant ferromagnetism in Ni: Spin polarization of photoelectrons from the (110) surface

The spin polarization $P\left(h\nu \right)$ of electrons emitted from Ni(110) has been measured as a function of photon energy $h\nu$ in the threshold region. The spin polarization is -52% at photothreshold and becomes positive (i.e., preferential direction of the magnetic moments parallel to the magnetization) at a crossover energy of 0.32 eV. By a symmetry projected density-of-states model it is shown that the measured $P\left(h\nu \right)$ curve for Ni(110) is closely related to the one of the Ni(110) surface. With this argument the values of both threshold spin polarization and crossover energy can be derived. Photoemission from the (110) face of this strong itinerant ferromagnet is proposed as another relatively simple method for producing polarized electron beams.