Effects of M=Si, Ga and Al for Co substitution on the electronic properties of RCo4M as probed by XPS

• Co 3s exchange splitting, the valence bands and the chemical shifts in RCo5−xMx.
• The existence of the local magnetic moments on Co sites.
• Co 3d band partial filling due to hybridization with R 5d6s and M 3sp, 4sp states.

The electronic properties of RCo5−xMx (R=Er, Sm, Tm; M=Si, Ga, Al; x=0 and 1) compounds were investigated by X-ray photoelectron spectroscopy (XPS). The study was focused on the Co 3s exchange splitting, the valence bands and chemical shifts of the elements from the analyzed compounds. The Co 2p3/2 core-level chemical shifts were described by means of the Auger parameters and Wagner plot. The hybridization between the R 5d6s and M 3sp and 4sp states and Co 3d states leads to a partial filling of the Co 3d band and to a decrease of the Co magnetic moments in comparison with the value in pure Co metal, in good agreement with the magnetic measurements.