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

The role of electron spin in photoelectric emission from the 2s, 2p1/2, 2p3/2, 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 Co₆₆{Fe}₄Ni₁{B}₁₄Si₁₅. 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 L₁{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 ${Co}₆₆Fe₄{Ni}₁B₁₄{Si}₁₅$ 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.