Effect of Composition near the Layer Boundary on GMR for Co/Cu, Ag Multilayers Electrodeposited by Pulse Method

Ueda, Y.; Houga, T.; Yamada, Akihiro; Zaman, H.

doi:10.3379/jmsjmag.23.120

Cited by 6 publications

(4 citation statements)

References 11 publications

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“…6. The results of Ueda et al 12 show the same features: the non-saturating MR(H) curves obtained for Cu thicknesses around their first observed GMR maximum (d Cu  1.5 nm) are dominated by an SPM term whereas split MR peaks with low saturation fields appear for Cu layer thicknesses around 3 to 4 nm. It should also be noted that their first GMR maximum appears roughly at a Cu layer thickness where usually FM coupling is observed for physically deposited Co/Cu multilayers.…”

Section: Reports With "Oscillatory" Gmr Behavioursupporting

confidence: 64%

“…From among the papers reporting on an "oscillation" of the GMR magnitude for electrodeposited Co/Cu multilayers, [11][12][13][14][15] we discuss first the results by Jyoko et al 13 For a multilayer with d Cu around 1 nm, these authors present an MR(H) curve which unambiguously reveals a dominant SPM contribution. Therefore, the high GMR value at this Cu layer thickness cannot originate from an AF coupled state and this conclusion is further supported by the M(H) curve reported for the same sample since it shows a large remanence whereas an AF-coupled state should exhibit a low remanence.…”

Section: Reports With "Oscillatory" Gmr Behaviourmentioning

confidence: 99%

“…Based on the argumentation presented above, we can conclude that in the above described two works 12,13 no evidence for a GMR oscillation corresponding to that observed in physically deposited Co/Cu multilayers can be identified.…”

Section: Reports With "Oscillatory" Gmr Behaviourmentioning

confidence: 99%

“…8 and 9). Two or more peaks in the spacer layer thickness dependence of the GMR magnitude have been reported for electrodeposited multilayers such as Ni-Cu/Cu, 10,11 Co-Cu/Cu, [11][12][13][14][15] Co-Ni-Cu/Cu, [16][17][18] Fe-Co-Cu/Cu 19 And Co-Ag/Ag 12 (due to the commonly applied single-bath technique, 8,9 the magnetic layer of electrodeposited multilayers unavoidably contains a few percent of the nonmagnetic element). These peaks were often claimed as resulting from an oscillatory exchange coupling between the adjacent layer magnetizations.…”

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confidence: 99%

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Giant magnetoresistance in electrodeposited Co-Cu/Cu multilayers: Origin of the absence of oscillatory behavior

et al. 2009

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─ A detailed study of the evolution of the magnetoresistance was performed on electrodeposited Co/Cu multilayers with Cu layer thicknesses ranging from 0.5 nm to 4.5 nm. For thin Cu layers (up to 1.5 nm), anisotropic magnetoresistance (AMR) was observed whereas multilayers with thicker Cu layers exhibited clear giant magnetoresistance (GMR) behaviour. The GMR magnitude increased up to about 3.5 to 4 nm Cu layer thickness and slightly decreased afterwards. According to magnetic measurements, all samples exhibited ferromagnetic (FM) behaviour. The relative remanence turned out to be about 0.75 for both AMR and GMR type multilayers. This clearly indicates the absence of an antiferromagnetic (AF) coupling between adjacent magnetic layers for Cu layers even above 1.5 nm where the GMR effect occurs. The AMR behaviour at low spacer thicknesses indicates the presence of strong FM coupling (due to, e.g., pin-holes in the spacer and/or areas of the Cu layer where the layer thickness is very small). With increasing spacer thickness, the pin-hole density reduces and/or the layer thickness uniformity improves which both lead to a weakening of the FM coupling. This improvement in multilayer structure quality results in a better separation of magnetic layers and the weaker coupling (or complete absence of interlayer coupling) enables a more random magnetization orientation of adjacent layers, all this leading to an increase of the GMR. Coercive field and zero-field resistivity measurements as well as the results of a structural study reported earlier on the same multilayers provide independent evidence for the microstructural features established here. A critical analysis of former results on electrodeposited Co/Cu multilayers suggests the absence of an oscillating GMR in these systems. It is pointed out that the large GMR reported previously on such Co/Cu multilayers at Cu layer thicknesses around 1 nm can be attributed to the presence of a fairly large superparamagnetic (SPM) fraction rather than being due to a strong AF coupling. In the absence of SPM regions as in the present study, AMR only occurs at low spacer thicknesses due to the dominating FM coupling.

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Section: Reports With "Oscillatory" Gmr Behavioursupporting

confidence: 64%