Argonne National Laboratory Center for Nanoscale Materials U.S. Department of Energy

CNM Research Highlighted in Scientific Journal

Applied Physics Letters cover for September 24, 2007An article by Dr. Kristen Buchanan of the Electronic & Magnetic Materials & Devices Group at the Center for Nanoscale Materials, and collaborators at Argonne's Advanced Photon Source, Cornell University, and University of Illinois - Chicago, was recently featured on the cover of Applied Physics Letters.

Microscale single-layer ferromagnetic rings typically exhibit a magnetic vortex state at remanence, characterized by a flux-closed magnetic state with zero stray fields. Magnetic reversal in such systems yields a vanishing remanent magnetization. In contrast, the authors show that in individual layers in thin rings, which alternate magnetic and nonmagnetic materials (NiFe/Cu/Co), layer-resolved hysteresis loops, measured by using X-ray resonant magnetic scattering, exhibit the characteristics of a vortex formation, although photoelectron emission microscopy and micromagnetic simulations clearly prove that multidomain states are formed. This result is of considerable importance for the development of pseudo-spin-valve-type structures. (more...)

See V. Rose, X.M. Cheng, D.J. Keavney, J.W. Freeland, K.S. Buchanan, B. Ilic, and V. Metlushko, "The breakdown of the fingerprinting of vortices by hysteresis loops in circular multilayer ring arrays,"; Appl. Phys. Lett. 91, 132501 (24 September 2007).

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