MAGNETISM AND STRUCTURE IN HEXAGONAL FE/RU SUPERLATTICES WITH SHORT PERIODICITY

We present recent results on the structure and on the magnetic properties of Fe/Ru superlattices. Detailed knowledge of the local structure is obtained from X-ray diffraction, including in the anomalous mode, and by EXAFS, thus bringing evidence that Fe layers correspond to an expansion exceeding 10%. The magnetic state is mostly characterized by Mossbauer spectroscopy and also by magnetization measurements, thus demonstrating that the internal Fe layer carry a moment of about 2-mu-B, whereas the two interfacial layers bear no moment. Except for the extension of the non-magnetic interface, these results are in agreement with theoretical predictions of Kubler, which indicate an high-spin metastable state for such an expanded hcp Fe phase.