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

• Published in: Thin solid films Vol. 460; no. 1-2; pp. 256 - 263
• Main Authors: RAFAJA, David, EBEN, Jörg, FARBER, Paul, SIEGLE, Henrik, MIEHE, Gerhard, MARTZ, Nathalie, KNAPP, Michael, STAHL, Branko, GHAFARI, Mohammad, HAHN, Horst, FUESS, Hartmut, SCHMOLLNGRUBER, Peter
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier Science 22-07-2004
• Subjects: Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization; Cold working, work hardening; annealing, quenching, tempering, recovery, and recrystallization; textures; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Interfacial magnetic properties (multilayers, magnetic quantum wells, superlattices, magnetic heterostructures); Magnetic properties and materials; Magnetic properties of surface, thin films and multilayers; Materials science; Physics; Treatment of materials and its effects on microstructure and properties; Inorganic compounds; Real structure; Electron diffraction; Roughness; Selected-area electron diffraction; Iron alloys; Crystal growth from vapors; XRD; Small angle X ray scattering; Small-angle X-ray scattering; Degradation; Multilayers; X-Ray diffraction; Copper; Annealing; Gold alloys; Co/Cu-multilayers; Magnetic field effects; Giant magnetoresistance; Experimental study; Interfaces; Transmission electron microscopy; Transition elements; Copper alloys; Sputter deposition; Silver alloys; Cobalt alloys; Transition element alloys
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2004.01.099

Annealing of the (1.1 nm Co90Fe10/2.2 nm Cu)x20 and (1.1 nm Co90Fe10 /2.2 nm Cu85Ag10Au5)x20 multilayers at 235 DGC 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 DGC 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.