Ohldag Hendrik, Shi Hongtao, Arenholz Elke, Stöhr Joachim, Lederman David
Stanford Synchrotron Radiation Laboratory, Stanford University, P.O. Box 20450, Menlo Park, California 94025, USA.
Phys Rev Lett. 2006 Jan 20;96(2):027203. doi: 10.1103/PhysRevLett.96.027203. Epub 2006 Jan 17.
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) .
