Regensburg 2002 – wissenschaftliches Programm

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MA: Magnetismus

MA 21: Elektronentheorie

MA 21.1: Vortrag

Freitag, 15. März 2002, 10:45–11:00, H22

Probing magnetic susceptibilities using the field-induced magnetic circular dichroism — •H. Ebert and S. Mankovskyy — Dept. Chemie (Physikalische Chemie), Universität München, Butenandtstr. 5-13, 81377 München, Germany

The magnetic circular dichroism in X-ray absorption (MCXD) is now a standard tool to probe the spin and orbital moments in magnetic materials by exploiting the so-called sum rules. In these systems the magnetic dichroism may be ascribed to the spontaneous exchange splitting. On the other hand, it its known that the magneto-optical Faraday effect, for example, can be observed for magnetic materials as well as for non-magnetic materials if they are exposed to a magnetic field. Accordingly, magnetic circular dichroism in X-ray absorption should be observable also in non-magnetic materials exposed to a magnetic field. A theoretical description of such an experiment is presented that is based on a combination of a fully relativistic linear response formalism and a corresponding treatment of magnetic circular dichroism. It is demonstrated that application of the magnetic sum rules now gives access to the spin and orbital element projected susceptibility of the system under investigation. In particular one finds that it is only the VanVleck contribution to the orbital susceptibility that is probed. In contrast to spontaneously magnetized systems, however, there are orbital contributions derived from the dichroic signal that stem from the external field and also from the intrinsic spin-orbit coupling. Illustrating examples will be presented for various transition metal systems that will demonstrate the usefulness and applicability of the new approach.