CROSSOVER FROM NEGATIVE TO POSITIVE SPIN POLARIZATION IN THE PHOTOYIELD FROM NI(111) NEAR THRESHOLD

The measured spin polarization of the photoelectrons emitted from Ni(111) shows a crossover from negative to positive values at 270 90 meV above photothreshold. This is in constrast to the case of Ni(100), where a crossover at about 75 meV occurs. A single-particle photoemission calculation with an exchange splitting of 0.33 eV, and which does not invoke emission from surface states, is in good agreement with the experimental results for both faces. These new results corroborate the empirical band structure obtained by Eastman and co-workers from angle-resolved photoemission data. © 1979 The American Physical Society.