Perpendicular Exchange Bias in (Co/Pt)n Multilayers

Kelvin Elphick; Kevin Dermot O'Grady; Gonzalo Vallejo Fernandez

doi:10.1109/TMAG.2019.2892205

Perpendicular Exchange Bias in (Co/Pt)_n Multilayers

Kelvin Elphick, Kevin Dermot O'Grady, Gonzalo Vallejo Fernandez

Research output: Contribution to journal › Article › peer-review

Abstract

For solid state magnetic memories and other potential devices based on giant magnetoresistance and tunneling magnetoresistance effects, it is invariably required that one ferromagnetic layer remains with its magnetization pinned in a given direction. The other ferromagnetic layer is then free to rotate creating the magnetoresistive effect. The fixing or pinning of one of the ferromagnetic layers can be achieved by using a material with a high coercivity or significantly higher anisotropy than the other layer. In conventional devices with in-plane anisotropy this is achieved by the use of the exchange bias phenomenon where the pinned layer is coupled to an antiferromagnetic layer typically consisting of IrMn. In this work we consider strategies to achieve the exchange bias phenomena in materials with strong perpendicular orientation to the magnetization and the potential for achieving the required exchange bias. We report on successfully achieving this objective in a (Co/Pt)_n system. We have achieved values of loop shift approaching 700 Oe at room temperature and blocking temperatures in excess of 500K.

Original language	English
Article number	4800106
Number of pages	6
Journal	IEEE Transactions on Magnetics
Volume	55
DOIs	https://doi.org/10.1109/TMAG.2019.2892205
Publication status	Published - 23 Jan 2019

Bibliographical note

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.

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10.1109/TMAG.2019.2892205

Cite this

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title = "Perpendicular Exchange Bias in (Co/Pt)n Multilayers",

abstract = "For solid state magnetic memories and other potential devices based on giant magnetoresistance and tunneling magnetoresistance effects, it is invariably required that one ferromagnetic layer remains with its magnetization pinned in a given direction. The other ferromagnetic layer is then free to rotate creating the magnetoresistive effect. The fixing or pinning of one of the ferromagnetic layers can be achieved by using a material with a high coercivity or significantly higher anisotropy than the other layer. In conventional devices with in-plane anisotropy this is achieved by the use of the exchange bias phenomenon where the pinned layer is coupled to an antiferromagnetic layer typically consisting of IrMn. In this work we consider strategies to achieve the exchange bias phenomena in materials with strong perpendicular orientation to the magnetization and the potential for achieving the required exchange bias. We report on successfully achieving this objective in a (Co/Pt)n system. We have achieved values of loop shift approaching 700 Oe at room temperature and blocking temperatures in excess of 500K. ",

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AB - For solid state magnetic memories and other potential devices based on giant magnetoresistance and tunneling magnetoresistance effects, it is invariably required that one ferromagnetic layer remains with its magnetization pinned in a given direction. The other ferromagnetic layer is then free to rotate creating the magnetoresistive effect. The fixing or pinning of one of the ferromagnetic layers can be achieved by using a material with a high coercivity or significantly higher anisotropy than the other layer. In conventional devices with in-plane anisotropy this is achieved by the use of the exchange bias phenomenon where the pinned layer is coupled to an antiferromagnetic layer typically consisting of IrMn. In this work we consider strategies to achieve the exchange bias phenomena in materials with strong perpendicular orientation to the magnetization and the potential for achieving the required exchange bias. We report on successfully achieving this objective in a (Co/Pt)n system. We have achieved values of loop shift approaching 700 Oe at room temperature and blocking temperatures in excess of 500K.

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