The antiferromagnetic structures of IrMn3 and their influence on exchange-bias.
We have determined the magnetic structures of single-crystal thin-films of IrMn3 for the crystallographic phases of chemically-ordered L12, and for chemically-disordered face-centred-cubic, which is the phase typically chosen for information-storage devices. For the chemically-ordered L12 thin-film, we find the same triangular magnetic structure as reported for the bulk material. We determine the magnetic structure of the chemically-disordered face-centred-cubic alloy for the first time, which differs from theoretical predictions, with magnetic moments tilted away from the crystal diagonals towards the face-planes. We study the influence of these two antiferromagnetic structures on the exchange-bias properties of an epitaxial body-centred-cubic Fe layer showing that magnetization reversal mechanism and bias-field in the ferromagnetic layer is altered significantly. We report a change of reversal mechanism from in-plane nucleation of 90° domain-walls when coupled to the newly reported cubic structure towards a rotational process, including an out-of-plane magnetization component when coupled to the L12 triangular structure.
Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel. akohn@exchange.bgu.ac.il
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Kohn
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Kovács
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Fan
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McIntyre
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Ward
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D003198:Computer Simulation; D007495:Iridium / Q000737:chemistry*; D060526:Magnetic Fields; D008345:Manganese / Q000737:chemistry*; D008422:Materials Testing; D008956:Models, Chemical
D008345:Manganese; D007495:Iridium