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Changes in the real structure and magnetoresistance of Co90Fe10/Cu and Co90Fe10/Cu85Ag10Au5 multilayers after annealing

Rafaja, David and Ebert, Jörg and Miehe, Gerhard and Martz, Nathalie and Knapp, Michael and Stahl, Branko and Ghafari, Mohammad and Hahn, Horst and Fuess, Hartmut and Schmollngruber, Peter and Farber, Paul and Siegle, Henrik (2004):
Changes in the real structure and magnetoresistance of Co90Fe10/Cu and Co90Fe10/Cu85Ag10Au5 multilayers after annealing.
In: Thin Solid Films, Elsevier Science Publishing Company, pp. 256-263, 460, (1-2), ISSN 00406090, [Online-Edition: http://dx.doi.org/10.1016/j.tsf.2004.01.099],
[Article]

Abstract

Annealing of the (1.1 nm Co90Fe10/2.2 nm Cu)×20 and (1.1 nm Co90Fe10/2.2 nm Cu85Ag10Au5)×20 multilayers at 235 °C improved their magnetoresistance as compared to the virgin samples. Annealing at higher temperatures resulted in degradation of the magnetoresistance effect. This observation raised the motivation of a detailed structural study using small-angle X-ray scattering, wide-angle X-ray diffraction, electron diffraction and transmission electron microscopy with the aim to link the structural changes in the system to the changes in the magnetoresistance. The structure studies have shown that the maximum of the magnetoresistance observed after annealing at 235 °C is related to the separation of Co90Fe10 and Cu, which are partly intermixed at interfaces after the deposition process. The decay of the GMR effect at higher annealing temperatures is caused by an increase of the interface roughness, which led in the Co90Fe10/Cu multilayers to occurrence of non-continuous interfaces and to short-circuiting of magnetic layers. In the Cu85Ag10Au5 multilayers, the combination of small-angle X-ray scattering and wide-angle X-ray diffraction has shown that Cu85Ag10Au5 did not form an alloy with the nominal composition: Only a part of Au and Ag was dissolved in the copper structure; the remainder of Ag and Au formed precipitates.

Item Type: Article
Erschienen: 2004
Creators: Rafaja, David and Ebert, Jörg and Miehe, Gerhard and Martz, Nathalie and Knapp, Michael and Stahl, Branko and Ghafari, Mohammad and Hahn, Horst and Fuess, Hartmut and Schmollngruber, Peter and Farber, Paul and Siegle, Henrik
Title: Changes in the real structure and magnetoresistance of Co90Fe10/Cu and Co90Fe10/Cu85Ag10Au5 multilayers after annealing
Language: English
Abstract:

Annealing of the (1.1 nm Co90Fe10/2.2 nm Cu)×20 and (1.1 nm Co90Fe10/2.2 nm Cu85Ag10Au5)×20 multilayers at 235 °C improved their magnetoresistance as compared to the virgin samples. Annealing at higher temperatures resulted in degradation of the magnetoresistance effect. This observation raised the motivation of a detailed structural study using small-angle X-ray scattering, wide-angle X-ray diffraction, electron diffraction and transmission electron microscopy with the aim to link the structural changes in the system to the changes in the magnetoresistance. The structure studies have shown that the maximum of the magnetoresistance observed after annealing at 235 °C is related to the separation of Co90Fe10 and Cu, which are partly intermixed at interfaces after the deposition process. The decay of the GMR effect at higher annealing temperatures is caused by an increase of the interface roughness, which led in the Co90Fe10/Cu multilayers to occurrence of non-continuous interfaces and to short-circuiting of magnetic layers. In the Cu85Ag10Au5 multilayers, the combination of small-angle X-ray scattering and wide-angle X-ray diffraction has shown that Cu85Ag10Au5 did not form an alloy with the nominal composition: Only a part of Au and Ag was dissolved in the copper structure; the remainder of Ag and Au formed precipitates.

Journal or Publication Title: Thin Solid Films
Volume: 460
Number: 1-2
Publisher: Elsevier Science Publishing Company
Uncontrolled Keywords: Co/Cu-multilayers, Real structure, Small-angle X-ray scattering, X-Ray diffraction, Transmission electron microscopy
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Joint Research Laboratory Nanomaterials
11 Department of Materials and Earth Sciences > Material Science > Structure Research
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 08 Feb 2013 08:34
Official URL: http://dx.doi.org/10.1016/j.tsf.2004.01.099
Identification Number: doi:10.1016/j.tsf.2004.01.099
Funders: D.R. appreciates the support of his work through the Alexander von Humboldt Foundation., J.E. acknowledges the support via the German BMBF as a part of the Robert Bosch GmbH research project on magnetoelectronics., SAXS measurements done at HASYLAB/DESY (Hamburg) were supported from the BMBF project # 05 KS1RDA/9.
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