Controlling the magnetic reversal mechanism of exchange biased MnxOy/Ni80Fe20 bilayers through O+ implantation

•O+ implantations were used to modify the exchange bias of a MnxOy/Ni80Fe20 interface.•Exchange bias was maximized at an O+ fluence of 1017 ions/cm2.•Spin-reversal behaviour was investigated by polarised neutron reflectometry.•Before O+ implantation, coherent and non-coherent magnetic spin reversal...

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Bibliographic Details
Published in:Journal of magnetism and magnetic materials 2019-04, Vol.476, p.437-446
Main Authors: Zhang, Ji, Causer, Grace L., Liu, Xinzhi, Ionescu, Mihail, Li, Sean, Lin, Ko-Wei, Klose, Frank
Format: Article
Language:English
Subjects:
Bias
Chemical properties
Coercivity
Coherence
Crystallography
Data analysis
Exchange bias
Implantation
Ion beams
Ion-beam implantation
Magnetic measurement
Magnetic properties
Magnetic reversal
Organic chemistry
Polarised neutron reflectometry
Reflectometry
Transmission electron microscopy
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Summary:•O+ implantations were used to modify the exchange bias of a MnxOy/Ni80Fe20 interface.•Exchange bias was maximized at an O+ fluence of 1017 ions/cm2.•Spin-reversal behaviour was investigated by polarised neutron reflectometry.•Before O+ implantation, coherent and non-coherent magnetic spin reversal is observed.•After O+ implantation, a coherent spin rotation reversal mechanism is observed only. This work investigates the different magnetic reversal mechanisms of as-grown and oxygen-ion (O+) implanted MnxOy/Ni80Fe20 bilayers. A MnxOy/Ni80Fe20 bilayer was prepared by ion-beam sputter deposition in an Ar+ atmosphere using a partially oxidised Mn target. Oxygen implantations were then performed using 8 keV O+ ions at fluences of 1016, 1017 and 1018 ions/cm2 to modify the exchange bias strength at the MnxOy/Ni80Fe20 interface. The magnetic, crystallographic and chemical properties of the bilayers before and after O+ implantation were studied using transmission electron microscopy, X-ray reflectometry, magnetometry and polarised neutron reflectometry. The results show an overall improved exchange bias and coercivity for the O+ implanted bilayers. The 1017 ions/cm2 implanted sample shows the greatest improvement in exchange bias and was further studied for its detailed spin-reversal behaviour using polarised neutron reflectometry. Data analysis in the magnetically-trained state reveals a coexistence of coherent rotational and non-coherent magnetic spin reversal in the as-grown sample and a solely coherent spin rotation reversal mechanism for the O+ implanted MnxOy/Ni80Fe20 bilayer.
ISSN:0304-8853
1873-4766
DOI:10.1016/j.jmmm.2018.12.076