Jenkins, Sarah, Fan, Wei Jia, Gaina, Roxana et al. (3 more authors) (2020) Atomistic origin of exchange anisotropy in noncollinear γ-IrMn3 -CoFe bilayers. Physical Review B. 140404(R). ISSN 2469-9969
Abstract
Antiferromagnetic spintronic devices could offer ultrafast dynamics and a higher data density than conventional ferromagnetic devices. One of the challenges in designing such devices is the control and detection of the magnetization of the antiferromagnet due to its lack of stray fields, and this is often achieved through the exchange bias effect. In exchange biased systems, the pinned spins are known to comprise a small fraction of the total number of interface spins, yet their exact nature and physical origin has so far been elusive. Here we show that in the technologically important disordered γ-IrMn3-CoFe structure, the pinned spins arise from the small imbalance in the number of spins in each magnetic sublattice in the antiferromagnet due to the naturally occurring atomic disorder. These pinned spins are strongly coupled to the bulk antiferromagnet, explaining their stability. Moreover, we find that the ferromagnet strongly distorts the interface spin structure of the antiferromagnet, causing a large reversible interface magnetization that does not contribute to exchange bias but does increase the coercivity. We find that the uncompensated spins are not localized spins which occur due to point defects or domain walls but instead constitute a small motion of every antiferromagnet spin at the interface. This unexpected finding resolves one of the long-standing puzzles of exchange bias and provides a route to developing optimized nanoscale antiferromagnetic spintronic devices.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details. |
Dates: |
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Institution: | The University of York |
Academic Units: | The University of York > York Institute for Materials Research The University of York > Faculty of Sciences (York) > Physics (York) |
Depositing User: | Pure (York) |
Date Deposited: | 18 Nov 2020 16:40 |
Last Modified: | 25 Nov 2024 00:35 |
Published Version: | https://doi.org/10.1103/PhysRevB.102.140404 |
Status: | Published |
Refereed: | Yes |
Identification Number: | 10.1103/PhysRevB.102.140404 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:168150 |