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Synchrotron study of iron and its oxides wins PhD prize


Oxidation can cause iron bridges to rust through – and yet an iron oxide coating on the Eiffel tower has helped it survive this long. The double-edged nature of iron’s many oxides was the subject of University of Hamburg/DESY student Sebastien Couet’s doctoral project. His research was carried out jointly at the Deutsches Elektronen-Synchrotron and the ESRF, and the finished thesis has received congratulations from the Association of the Friends and Sponsors of DESY as one of the two best doctoral studies of 2009. Dr. Couet’s study of the growth and structure of iron and iron oxide combinations indicates a possible new way to make nano-scale magnetic structures.

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Couet produced sandwich-layered systems consisting of alternating layers of iron and its natural oxide, and observed their growth using nuclear resonance techniques at beamline ID18. This proved to be a crucial key to understand the mutual influence of the two compounds. The magnetic and chemical structure of these systems revealed that the individual iron layers do not have parallel magnetic fields, but are instead perpendicular to one another. This is due to the structure of the oxide between the iron layers.

The results of Couet’s thesis point out new opportunities for using iron oxides to stabilise novel magnetic structures, and for this excellent work, he receives the annual PhD thesis prize for the best doctoral thesis on DESY physics.

Diagram of Iron - Iron Oxide System

This diagram shows some of Couet’s work. The magnetic field directions in a sandwich of iron and iron oxide are probed using the iron isotope 57Fe. The inset box show the results: with no external magnetic field applied, the fields in the top and bottom slice of the sandwich are perpendicular. As the external magnetic field increases, they become parallel.


Further information on the winners of the annual PhD thesis prize from the Association of the Friends and Sponsors of DESY.