EPL, 87 (2009) 67007
DOI: 10.1209/0295-5075/87/67007

On the importance of the magnetic dipole term T_z in analyzing X-ray magnetic circular dichroism spectra of clusters

O. Šipr¹, J. Minár² and H. Ebert<sup>2

1</sup>   Institute of Physics of the ASCR v. v. i. - Cukrovarnická 10, CZ-162 53 Prague, Czech Republic, EU
²   Universität München, Department Chemie und Biochemie - Butenandtstr. 5-13, D-81377 München, Germany, EU

sipr@fzu.cz

received 19 June 2009; accepted in final form 15 September 2009; published September 2009
published online 12 October 2009

Abstract
Employing ab initio relativistic impurity Green function calculations to Fe and Co clusters on Ni and Au surfaces, we assess the usability of the X-ray magnetic circular dichroism (XMCD) spin sum rule for studying magnetism of supported transition metal clusters. We demonstrate that neglect of the magnetic dipole term T_z might lead to a completely false estimate of how the spin magnetic moment depends on the cluster size. In particular, this would be the case of Co_N clusters on Au(111) and on Pt(111).

PACS
78.70.Dm - X-ray absorption spectra.
75.10.Lp - Band and itinerant models.
75.75.+a - Magnetic properties of nanostructures.

© EPLA 2009