T. Yokoyama et al., Anisotropic magnetization of CO adsorbed on ferromagnetic metal thin filmsstudied by X-ray magnetic circular dichroism, J ELEC SPEC, 119(2-3), 2001, pp. 207-214
Citations number
17
Categorie Soggetti
Spectroscopy /Instrumentation/Analytical Sciences
Journal title
JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA
We observed O K-edge X-ray magnetic circular dichroism (XMCD) of molecular
CO adsorbed on Co and Ni epitaxial films grown on a Cu(001) substrate. The
films examined are 6 ML Ni, thick (>100 ML) Ni, 4 ML fec Co which show in-p
lane magnetic anisotropy, while the others, 10 ML Ni and similar to2 ML Co
on 30 ML Ni, exhibit perpendicular magnetic anisotropy (PMA). In the PMA fi
lms, negative XMCD signals were observed at the O 1s --> CO 2 pi* transitio
n, while in the in-plane magnetization films, positive XMCD signals were de
tected at the same transition. These findings imply the presence of orbital
magnetic moments at the CO 2 pi* levels since the CO 2 pi* orbitals are pa
rtially filled due to hybridization of metal 3d levels, in spite that CO is
inherently diamagnetic in a gas phase. The observed XMCD signs indicate pa
rallel and antiparallel alignments of the CO 2 pi* orbital magnetic moments
for the PMA and in-plane magnetization films, respectively. The direction
of the orbital moments is tried to interpret within a framework of chemical
bonding between CO and metal atoms. (C) 2001 Elsevier Science B.V. All rig
hts reserved.