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NPG Scientific Reports 3 (2013) 2412

The antiferromagnetic structures of IrMn_{3} and their influence on exchange-bias

Amit Kohn, András Kovács, Raymond Fan, Garry McIntyre, Roger C.C. Ward and Jon P. Goff

Exchange-bias occurs when a ferromagnetic layer is coupled to an antiferromagnetic layer thus introducing unidirectional anisotropy due to interface coupling. The exchange-bias phenomenon is of technological importance for information-storage devices, for example to pin the magnetization of the reference magnetic layer in a magnetic tunnel junction.

ER-C scientists in collaboration have determined the magnetic structure of IrMn_{3} for the crystallographic phases of chemically ordered L1_{2} structure, and for chemically disordered fcc structures. The magnetic structure of L1_{2}-IrMn_{3} is a triangular as reported for bulk material. The magnetic structure of fcc-IrMn_{3} was found to be different from theoretical predictions, with magnetic moments tilted away from crystal diagonals towards the fcc planes. 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 L1_{2}triangular structure.

Further reading:

A. Kohn, A. Kovács, R. Fan, G.J. McIntyre, R.C.C. Ward and J.P. Goff: The antiferromagnetic structures of IrMn_{3} and their influence on exchange-bias, NPG Scientific Reports 3 (2013) 2412.

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