Spin Polarization of X‐Ray Photoelectrons in Nickel

It is shown that under certain conditions an X‐ray photoelectron spectrum is represented as a sum of additive contributions from each of the atoms separately. Discussing the problem of measuring the electron spin polarization (ESP), conclusions are made about advantages of the X‐ray photoelectron emission as compared with the optical method. The results of the ESP numerical calculations for nickel based on Hubbard's model with a small concentration of electrons (holes) and in the approximation of a local effective interaction are reported. Drastic correlation effects for ESP are found. The correlation interaction may change the sign of ESP at the Fermi level compared with the one‐electron Hartree‐ Fock calculations, and provides an additional hump of the ESP energy distribution at the bottom of the spectrum.