Measurement of the antiferromagnet activity in exchange bias systems

Gonzalo Vallejo Fernandez, T. Deakin, K. O'Grady, S. Oh, Q. Leng, M. Pakala

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In this work, we describe the results of a recent set of experimental measurements on samples of CoFe/IrMn ferromagnet/antiferromagnet (AF) bilayer exchange bias materials. Careful magnetic measurement protocols and detailed particle size measurements have enabled us to confirm the link between the exchange field (H-ex) and the distribution of grain volumes in the IrMn AF layer. This can be achieved by fitting the blocking temperature curve to obtain an effective value for the Neel temperature (T-N). The value of (T-N) is then used to determine the stable and set fraction of the grain volume distribution. Through a comparison of samples with different seed layer structures, we demonstrate control of the exchange bias where almost all the AF grains contribute to H-ex. These samples have an AF with a mean grain diameter of 8.7 nm and an anisotropy constant of 7.8x10(6) ergs/cc. Our results indicate a reduction in the value of the Neel temperature (T-N) of up to 100 K. (C) 2010 American Institute of Physics. [doi:10.1063/1.3340507]

Original languageEnglish
Article number09D709
Pages (from-to)-
Number of pages3
JournalJournal of Applied Physics
Issue number9
Publication statusPublished - 1 May 2010

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