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MA: Fachverband Magnetismus

MA 14: Invited Talks (joint seesion with O) Bruno / Göring

MA 14.2: Hauptvortrag

Dienstag, 27. März 2007, 14:30–15:00, H10

XMCD in TM Oxides: Are there hidden orbital moments in magnetite? — •Eberhard Goering — Max-Planck-Institiut für Metallforschung, Heisenbergstraße 3, 70569 Stuttgart

X-ray magnetic circular dichroism has become a powerful tool, used by scientists to gain a deep microscopic understanding of magnetism in an element specific and very sensitive manner. Sum-rules, based on integral spectral intensities, provide average spin- and orbital- magnetic moments in a quantitative way. It has been shown, that the shape of the spectra could be used to go beyond sum rules, providing a more detailed understanding of the magnetic polarization of different parts of the unoccupied band structure. The theoretical fundament for this approach has been recently theoretically confirmed. To exemplify the potential of this ansatz, absorption spectroscopy results of Magnetite will be presented, showing hidden orbital magnetism at the Fe site. This is very important, because orbital ordering and orbital magnetism is believed to play a key role in the understanding of the Verwey transition. On the other the hand, this transition plays also a fundamental and important role in solid state physics, which has been discussed frequently in the literature in the past decades.