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Parallel versus antiparallel interfacial coupling in exchange biased Co/FeF2
Hendrik Ohldag1, Hongtao Shi, Elke Arenholz
1Stanford Synchrotron Radiation Laboratory, Stanford University, P.O. Box 20450, Menlo Park, California 94025, USA.
Abstract:
By using the surface and element specificity of soft x-ray magnetic dichroism we provide direct experimental evidence for two different types of interfacial uncompensated Fe moments in exchange biased Co/FeF2 bilayers. Some moments are pinned and coupled antiparallel to the ferromagnet (FM). They give rise to a positive exchange bias and vanish above T(N) = 78 together with the antiferromagnet (AF) order. Other interfacial Fe moments are unpinned and coupled parallel to the FM. They persist up to 300 K and give rise to magnetic order at the AF surface even above T(N) .
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