Journal article
Exchange-bias in amorphous ferromagnetic and polycrystalline antiferromagnetic bilayers: Structural study and micromagnetic modeling
Ben-Gurion University of the Negev, Department of Materials Engineering and the Ilse Katz Institute for Nanoscale Science and Technology, , Beer-Sheva 84105, Israel1
University of Sheffield, Department of Engineering Materials, , Sheffield S1 3JD, United Kingdom2
University of Oxford, Department of Materials, , Parks Road, Oxford OX1 3PH, United Kingdom3
St. Poelten University of Applied Science, St. Poelten University of Applied Science, , 3100 St. Poelten, Austria4
We study the role of the structure of antiferromagnetic polycrystalline metallic films in determining the magnetic properties of an exchange-coupled amorphous ferromagnetic layer. The bilayers are sputter-deposited, highly textured {111} Ir22Mn78 and Co65.5Fe14.5B20 thin films. We focus on structural characterization of Ir22Mn78 as a function of layer thickness in the range having the strongest influence over the exchange-bias field and training effect.
We have used transmission electron microscopy to characterize defects in the form of interface steps and roughness, interdiffusion, twin- and grain-boundaries. Such defects can result in uncompensated magnetic spins in the antiferromagnet, which then contribute to exchange-bias. These experimental results form the basis of a general model, which uses finite element micromagnetic simulations.
The model incorporates the experimental structural parameters of the bilayer by implementing a surface integral technique that allows numerical calculations to solve the transition from an amorphous to a granular structure. As a result, a detailed calculation of the underlying magnetic structure within the antiferromagnetic material is achieved.
These calculations are in good agreement with micromagnetic imaging using Lorentz transmission electron microscopy and the macro-magnetic properties of these bilayers.
Language: | Undetermined |
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Publisher: | American Institute of Physics |
Year: | 2011 |
Pages: | 083924 |
ISSN: | 10897550 and 00218979 |
Types: | Journal article |
DOI: | 10.1063/1.3559261 |