# Dresden 2006 – wissenschaftliches Programm

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# MA: Magnetismus

## MA 2: Magnetic Thin Films I

### MA 2.1: Vortrag

### Montag, 27. März 2006, 10:15–10:30, HSZ 03

**Measuring the kernel of time-dependent density functional theory with X-ray absorption spectroscopy of ****3 d**

**transition metals**— •H. Wende

^{1}, A. Scherz

^{2}, E.K.U. Gross

^{1}, H. Appel

^{1}, C. Sorg

^{1}, K. Baberschke

^{1}, and K. Burke

^{3}—

^{1}Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin-Dahlem, Germany. —

^{2}SSRL, 2575 Sand Hill Road, Menlo Park, California 94025, USA —

^{3}Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Rd, Piscataway, NJ 08854, USA

We showed that the induced magnetic moments in ultrathin films of the
light 3d elements Ti, V and Cr at the interface to Fe cannot be determined
by the XMCD sum rule analysis at the *L*_{2,3} edges. The reasons are correlation
effects which result in the deviation of the intensity ratio (branching ratio)
from its statistical value. Therefore, we established a double-pole approximation
within time-dependent density functional theory to investigate these effects in detail.
A (2×2)
matrix of the matrix elements of the unknown exchange correlation kernel
is used to describe the shift of the two transitions (diagonal)
and the change of the branching ratio (off-diagonal elements).
We experimentally measure the branching
ratios and level splittings for these films, and
*deduce* these matrix elements.
It turns out that off-diagonal matrix elements are much smaller (factor 5) than the
diagonal ones which demonstrates that the change of the branching ratio for the light 3d elements
is simply due to transition repulsion, as the two transitions near
one another (reduced spin-orbit splitting).
Supported by BMBF (05 KS4 KEB 5).

[1] A. Scherz *et al.*, Phys. Rev. Lett. in print