Spin-resolved and high-energy-resolution XPS studies of cobalt metal and a cobalt magnetic glass

Abstract

The role of electron spin in photoelectric emission from the 2s, 2${\mathit{p}}_{1/2}$, 2${\mathit{p}}_{3/2}$, and 3p core levels of cobalt metal is investigated through a combination of spin-resolved x-ray-photoelectron spectroscopy (SRXPS) and high-energy-resolution XPS (HRXPS) studies. The sensitivity of the Co core-level spectra to a variation in the valence spin polarization is revealed by comparing the Co-metal data with SRXPS and HRXPS spectra from the amorphous cobalt-based ferromagnetic glass ${\mathrm{Co}}_{66}$${\mathrm{Fe}}_{4}$${\mathrm{Ni}}_{1}$${\mathrm{B}}_{14}$${\mathrm{Si}}_{15}$. The results demonstrate explicitly the role of intra-atomic exchange in deep-core-level photoemission from Co, and reveal core-hole spin dependencies to core-hole-induced electron-hole-pair excitation, to the ${\mathit{L}}_{1}$${\mathit{L}}_{2,3}$V Coster-Kronig transition rate, and to the rates of Auger transitions involving the valence band. The data also suggest that the reduction of the cobalt magnetic moment in the ${\mathrm{Co}}_{66}$${\mathrm{Fe}}_{4}$${\mathrm{Ni}}_{1}$${\mathrm{B}}_{14}$${\mathrm{Si}}_{15}$ glass results from the transfer of majority-spin 3d electron density into the minority-spin 3d band caused by a hybridization-induced weakening of the 3d electron-electron interaction.