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MA: Fachverband Magnetismus

MA 14: Magnetic Half Metals and Oxides

MA 14.7: Vortrag

Dienstag, 26. Februar 2008, 12:00–12:15, EB 202

Magnetism in Re-based ferrimagnetic double perovskites — Andreas Winkler¹, Narendirakumar Narayanan¹, Daria Mikhailova¹, Helmut Ehrenberg², Hartmut Fuess¹, Fabrice Wilhelm³, Andrei Rogalev³, and •Lambert Alff¹ — ¹Institut für Materialwissenschaft, TU Darmstadt — ²IFW Dresden — ³ESRF, Grenoble, France

We have investigated spin and orbital magnetic moments of the Re 5d ion in the double perovskites A₂FeReO₆ (A= Ba, Sr, Ca) by X-ray magnetic circular dichroism (XMCD) at the Re L_2,3 edges. In these ferrimagnetic compounds an unusually large negative spin and positive orbital magnetic moment at the Re atoms was detected. The presence of a finite spin magnetic moment in a ’non-magnetic’ double perovskite as observed in the double perovskites Sr₂ScReO₆ proves that Re has also a small, but finite intrinsic magnetic moment. These results further support a kinetic energy driven exchange model for the ferrimagnetic double perovskites. We further show for the examples of Ba and Ca that also the usually neglected alkaline earth ions undoubtedly also contribute to the magnetism in the ferrimagnetic double perovskites.