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Phys. Rev. Lett. 96, 027203 (2006) [4 pages]

Parallel versus Antiparallel Interfacial Coupling in Exchange Biased Co/FeF2

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Hendrik Ohldag1,*, Hongtao Shi2,†, Elke Arenholz3, Joachim Stöhr1, and David Lederman2
1Stanford Synchrotron Radiation Laboratory, Stanford University, P.O. Box 20450, Menlo Park, California 94025, USA
2Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315, USA
3Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

Received 21 December 2004; published 17 January 2006

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 TN=78  K 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 TN.

© 2006 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.96.027203
DOI:
10.1103/PhysRevLett.96.027203
PACS:
75.70.Cn, 75.50.Ee, 78.20.Ls

*Electronic address: hohldag@stanford.edu

†Presently at Department of Physics and Astronomy, Sonoma State University, Rohnert Park, CA 94928, USA.

 
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