Electronic structuresof amorphous M100-xZrx alloys (M = Fe, Co,Ni, Cu) studied using core-level x-ray photoemission spectroscopy

Abstract

The electronic structures of amorphous a-Fe100-xZrx and a-(Fe1-yMy)33Zr67alloys (M = Co, Ni, Cu) have been investigated by using x-rayphotoemission spectroscopy. For a-Fe100-xZrx,the linewidths of both the Fe 2p and Zr 3d core-level spectra becomenarrower with increasing x. Systematic line-shape analysisreveals that such a trend could be either due to the decrease in theAuger recombination process or due to the decrease in the exchangesplitting of core-hole electrons. The broad Zr 3d spectrum forx = 10 is decomposed into two peaks, suggesting a localized natureof the Zr 4d electrons in a-Fe90Zr10. Fora-(Fe1-yMy)33Zr67 (M = Co, Ni),the Fe 2p spectrum becomes narrower and the shoulder-like satellitestructure becomes more pronounced with increasing y, reflectingthe increasingly localized nature of the Fe 3d electrons. Incontrast, the M 2p spectra of a-(Fe1-yMy)33Zr67 remain essentially unchanged with varyingy, implying that the M 2p spectra of a-M100-xZrx are much less sensitive to the M ion species than to thefractional concentrations of M and Zr ions. As M varies from Fe toCo and Ni in a-M33Zr67, the Zr 3d spectrum exhibits asmall shift toward higher binding energy and a slight increase inthe linewidth. Band-structure calculations for ordered MZr2 (M = Fe, Co, Ni, Cu) predict that both the density of statesat the Fermi level N(EF) and the total number of valenceelectrons increase as M varies from Fe to Co and Ni, which isconsistent with the measured Zr 3d spectra of a-M33Zr67.