High-resolution angle-resolved photoemission spectra from Ni(100): Matrix element effects and spin-resolved initial and final state bands

Abstract

We have carried out extensive one-and three-step angle-resolved photoemission spectroscopy ͑ARPES͒ intensity computations on Ni͑100͒ within the band theory framework based on the local spin-density approximation. The results show a good overall level of accord with the recent high-resolution ARPES experiments on Ni͑100͒ which probe the majority-and minority-spin ⌺ 1 band along the ⌫-K direction near the Fermi energy (E F ), uncertainties inherent in our first-principles approach notwithstanding. The k ʈ and energy dependencies of various spectral features are delineated in terms of the interplay between changes in the initial-and finalstate bands and the associated transition matrix elements. The remarkable decrease observed with decreasing k ʈ in the ARPES intensity of the majority-spin ⌺ 1 band as it disperses below the E F as well as an enhanced spin polarization of the photoemitted electrons from the E F is shown to arise from the presence of a band gap in the final-state spectrum.

Final state effects in photoemission studies of Fermi surfaces

“…A key aspect of these results is the recognition that different aspects of the electronic structure are highlighted differently as a function of hν. In fact, they find that for hν below 25 eV, only the O 2 p component of the CuO 2 planes is sampled through p → d transitions despite the admixture of some Cu in that state [14]. Only at higher energies are the Cu states sampled.…”