Hamburg 2001 – wissenschaftliches Programm

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AM: Magnetismus

AM 1: Spektroskopie I & II

AM 1.5: Vortrag

Montag, 26. März 2001, 11:00–11:15, S 5.2

Magnetic Circular X-Ray Dichroism Investigations on US and UGa₂ Compounds — •Voicu Popescu¹, Hubert Ebert¹, and Andrei Rogalev² — ¹Department Chemie/Physikalische Chemie, Butenandtstr. 5-13, 81377 Muenchen, Deutschland — ²ESRF, BP220, F-38043, Grenoble, France

Recent experimental investigations at the K-edges of S and Ga in US and UGa₂ compounds found a very strong magnetic circular X-Ray dichroism (MCXD) sigal in the near-edge region, that is about two orders of magnitude higher compared to the Fe K-edge. This finding has been ascribed to the strong hybridisation between S (Ga) p- and U f-states.

To support this interpretation, theoretical investigations have been performed within the framework of spin-polarised relativistic multiple scattering theory (SPR-KKR). Our calculations of MCXD spectra included the Brooks’ orbital-polarisation term for f-electrons in the underlying Dirac Hamiltonian. This approach led to a rather good agreement with the experimental data and emphasised the role of the p-f hybridisation mechanism.

The dependence of the dichroic spectra on the orientation of the magnetisation was studied in addition. It was found, however, that this has only a minor influence on the MCXD spectra.