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Oxidation states and quality of upper interfaces in magnetic tunnel junctions: oxygen effect on crystallization of interfaces
KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF. (Spintronics)
KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF. (Spintronics)
2014 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 26, no 2, 026004- p.Article in journal (Refereed) Published
Abstract [en]

In this study, we have deposited an Fe-57 sensor layer at the upper interface, i.e. the interface between the oxide barrier and the upper electrode in selected magnetic tunnel junctions (MTJs), in order to perform nuclear resonant scattering with the aim of obtaining direct information on the magnetic properties and quality of this interface. This is a unique approach as it makes use of this powerful technique to give information at the atomic level, and specifically from the interface where the sensor layer is deposited. By varying sample tunnel barrier thicknesses and oxidation times in the preparation of this barrier, we have observed that longer oxidation time results in not only an increase of the magnetic hyperfine fields, but also causes an interesting crystallization and smoothing of the interface. We also observed that boron atoms diffuse away from the lower part of the upper FeCoB electrode toward the capping layer. An important observation, which has a crucial effect in tunnel magnetoresistance values, is the absence of any magnetically dead FeO layer at the interface. Another finding is that the deposition of Fe on MgO is much smoother than the deposition of MgO on Fe.

Place, publisher, year, edition, pages
2014. Vol. 26, no 2, 026004- p.
Keyword [en]
magnetic tunnel junction, magnetoresistive random access memory, interface, magnetism, nuclear resonant scattering
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Other Physics Topics
URN: urn:nbn:se:kth:diva-139510DOI: 10.1088/0953-8984/26/2/026004ISI: 000328329700026ScopusID: 2-s2.0-84890755282OAI: diva2:687425
Swedish Foundation for Strategic Research Swedish Research CouncilKnut and Alice Wallenberg Foundation

QC 20140114

Available from: 2014-01-14 Created: 2014-01-14 Last updated: 2014-01-14Bibliographically approved

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Zha, ChaolinÅkerman, Johan
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