Electrodeposition of Ni–Co–Cu/Cu multilayers

Péter, László; Katona, G.L.; Berényi, Z.; Vad, K.; Langer, G.A.; Tóth-Kádár, E.; Pádár, J.; Pogány, L.; Bakonyi, I.

doi:10.1016/j.electacta.2007.07.066

Cited by 29 publications

(24 citation statements)

References 11 publications

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“…8, in the two series labeled as (1)(2)(3)(4) and (51)(52)(53)(54)(55), the addition of a small amount of Ag + ions to the bath resulted definitely in an improvement of the GMR magnitude. For further additions of Ag + ions to the bath (typically with concentrations above 1%), the GMR magnitude showed an overall decrease down to very small GMR values for the highest Ag + ion concentrations applied.…”

Section: Methodsmentioning

confidence: 99%

“…The lateral homogeneity of the ion bombardment was checked by a profilometric analysis of the craters sputtered. The calculation methods of the composition vs. depth function was described earlier ( [52] and references cited therein).…”

Section: Methodsmentioning

confidence: 99%

“…Further details of the sample preparation process can be found in earlier papers. 46,[49][50][51][52] After the electrochemical sample preparation, the Si wafer was broken behind the multilayer sample in a manner that the deposit itself remained intact. Then, the deposit could easily be peeled off from the Si wafer so that the separation took place at the Si/Cr interface.…”

Section: Methodsmentioning

confidence: 99%

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Influence of Ag Additive to the Spacer Layer on the Structure and Giant Magnetoresistance of Electrodeposited Co/Cu Multilayers

Neuróhr

Péter

Pogány

et al. 2015

J. Electrochem. Soc.

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In order to explore the possible surfactant effect of Ag on the formation of electrodeposited multilayers, Co/Cu(Ag) multilayers were prepared by this technique and their structure and giant magnetoresistance (GMR) were investigated. The multilayers were deposited from a perchlorate bath with various amounts of Ag + ions in the solution for incorporating Ag atoms into the multilayer stack. Without Ag addition, secondary neutral mass spectroscopy (SNMS) indicated a well-defined composition modulation of the undermost Co/Cu bilayers. However, already at an Ag content as low as 1.8 at.% incorporated, SNMS showed a deterioration of the periodic multilayer structure. In agreement with the SNMS results, superlattice satellites were visible in the X-ray diffraction (XRD) patterns of the multilayers with up to 0.3 at.% Ag. The satellites were, however, very faint even for multilayers without Ag addition, indicating that the multilayers have high interface roughness and/or poor periodicity. In the absence of Ag and at the smallest Ag content investigated by XRD, a strong central multilayer peak and the weak superlattice satellites were complemented by weak diffraction maxima from non-periodic Co and Cu domains. In the Co/Cu(Ag) multilayer containing about 25 at.% Ag, i.e., nearly as much as Cu, XRD found a separate Ag(Cu) phase. In spite of the imperfect layered structure, a multilayer-type GMR behavior was observed in all samples up to about 10 at.% Ag incorporated in the multilayer stack. The GMR magnitude increased for Ag contents up to about 1 at.%, which implies that a small amount of Ag may have a beneficial effect through a slight modification of the layer growth and/or interface formation. However, for higher Ag contents beyond this level, the GMR was reduced in line with the structural degradation revealed by XRD and SNMS. For the highest Ag contents (above about 10 at.%), the GMR exhibited a behavior characteristic of a granular magnetic alloy, in agreement with the results of the structural study. One of the major obstacles hindering the realization of a high giant magnetoresistance (GMR) in electrodeposited (ED) ferromagnetic/non-magnetic (FM/NM) multilayers is that the nonmagnetic spacer layer cannot be electrodeposited as pinhole-free for layer thicknesses which are required to achieve high GMR and an oscillatory GMR behavior. 1 Sputtered Co/Cu multilayers 2-4 exhibit an oscillatory GMR and a room-temperature GMR of about 50% and 20% at about 1 and 2 nm Cu layer thicknesses, respectively. At these particular spacer thicknesses, a strong antiferromagnetic (AF) exchange coupling exists between the adjacent magnetic layers. It gives rise then to a large GMR effect since the AF coupling ensures an antiparallel alignment of the magnetizations of the neighboring magnetic layers in zero magnetic field. For spacer thicknesses between these so-called AF maxima, the exchange coupling is predominantly ferromagnetic. Thus, due to the parallel alignment of the layer magnetizations even in zero magnetic field, no GMR eff...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Influence of Ag Additive to the Spacer Layer on the Structure and Giant Magnetoresistance of Electrodeposited Co/Cu Multilayers

Neuróhr

Péter

Pogány

et al. 2015

J. Electrochem. Soc.

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mentioning

confidence: 99%

“…According to Tokarz et al, 10 the interface width of ED Cu͑200 nm͒/Ni͑200 nm͒ bilayers can also be estimated as being 20-30 nm, as shown by their secondary-ion mass spectrometric depth profile data. Later, Péter et al 11 and Katona et al 12 published the depth profile analysis of ED Co/Cu and Co-Ni/Cu multilayers. The interface width was estimated to be in the same range as in the study of Basile et al In the papers listed above, the thickness of a single layer was within the 20-100 nm range.…”

mentioning

confidence: 99%

Application of Surface Roughness Data for the Evaluation of Depth Profile Measurements of Nanoscale Multilayers

Bartok

Csík

Vad

et al. 2009

J. Electrochem. Soc.

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A secondary neutral mass spectrometric ͑SNMS͒ depth profile study of electrodeposited Co/Cu multilayers was performed. Depth profile measurements were performed both in the conventional way ͑i.e., starting the sputtering from the final deposit surface͒ and in the reverse manner ͑i.e., detaching the multilayers from the substrate and starting the analysis from the substrate side, which was very smooth as compared to the final deposit surface͒. The latter method could yield significantly larger intensity fluctuations in the SNMS spectra. Surface roughness data were measured with atomic force microscopy ͑AFM͒ for multilayers with different bilayer numbers but otherwise exhibiting the same layer structure as those used for the depth profiling. The experimental AFM surface roughness evolution was used to calculate the result of the depth profile measurements quantitatively. An excellent agreement was obtained between this calculation and the SNMS measurements. It was shown that the decrease in the intensity fluctuations during the depth profile analysis stems mainly from the increase in surface roughness of the samples studied, especially in the conventional sputtering mode. It was also concluded that the thickness fluctuation of the entire multilayer deposit and that of each layer are strongly correlated. DOI: 10.1149/1.3133182 .Nanoscale magnetic/nonmagnetic multilayers are in the forefront of materials research since the discovery of giant magnetoresistance ͑GMR͒ in these nanostructures.1,2 Multilayers are mostly produced by physical methods ͑evaporation, sputtering, and molecular beam epitaxy͒, some of them applying a fairly expensive high vacuum system. The feasibility of the electrodeposition of metallic magnetic/ nonmagnetic multilayers with GMR was demonstrated 3 a few years after the discovery of the phenomenon. Although electrodeposition has long been considered as a possible low cost alternative to the physical sample preparation techniques, the quality of the electrodeposited ͑ED͒ multilayers is still inferior to their physically produced analogs. The literature of the ED multilayer films with GMR amounts to some 140 papers, 4-6 but very little is known about why the sample quality, especially GMR, cannot achieve the properties of the samples prepared by physical methods.Although depth profile analysis is a very efficient tool for the characterization of element distribution and the interface quality of ED multilayer samples, only a few studies were published hitherto. Basile et al.7 studied the depth profile of ED Co/Cu sandwiches by Auger electron spectroscopy. They found that the observed interface width of approximately 20 nm is an inherent feature of the sample itself rather than the artifact of the sputtering method used for the depth profiling ͑although the sputtering also leads to some intermixing at a smaller depth scale 8,9 ͒. According to Tokarz et al., 10 the interface width of ED Cu͑200 nm͒/Ni͑200 nm͒ bilayers can also be estimated as being 20-30 nm, as shown by their secondary-ion mass spe...

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Electron‐Impact (EI) Secondary Neutral Mass Spectrometry (SNMS)

Kopnarski¹,

Jenett²

2011

Surface and Thin Film Analysis

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IntroductionSince the early days of sputtering it has been known that, for most cases, the fl ux of particles ejected from a solid under ion bombardment consists predominantly of sputtered neutral s ( SN )s [1] . Thus, in order to enhance sensitivity the pioneers of surface investigation by mass spectrometry applied the process of postionization [2] . Very shortly afterwards, however, due to the rather limited postionization effi ciency when using electron beam methods, and also because of diffi culties with parasitic ion and residual gas suppression, the direct detection of secondary ions provided an advantage over using the neutral component of the sputtered particle fl ux. As a consequence, sophisticated SIMS instruments were developed with, prior to SNMS, SIMS being introduced into the fi eld of surfaceand thin -fi lm analysis.In contrast, a serious limitation of SIMS -the so -called matrix effect -emerged whereby, for a certain concentration of an element X, the secondary ion yield could vary by orders of magnitude as a function of the surface contamination and matrix composition (see e.g., Ref.[3] ). Indeed, in many cases -and especially with unknown or technical samples that had changing matrices -this would hamper quantifi cation, or even make it impossible. Subsequently, during the early 1970s, H. Oechsner [4] developed a strategy to improve quantifi cation by using the effective postionization of the neutral particle fl ux via the electron component of a low -pressure noble gas plasma. In addition to the high postionization effi ciency, this special postionization arrangement provided two further advantages: (i) an almost perfect suppression of the secondary ions; and (ii) the possibility of a lowenergy primary bombardment which featured excellent depth resolution for sputter depth profi ling.In the meantime, electron beam and laser SNMS had also been developed for postionization purposes, and had expanded into the fi eld of applied surface -and thin -fi lm analysis. The latter technique is described fully in Chapter 10 of this

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Electrodeposition of Ni–Co–Cu/Cu multilayers

Cited by 29 publications

References 11 publications

Influence of Ag Additive to the Spacer Layer on the Structure and Giant Magnetoresistance of Electrodeposited Co/Cu Multilayers

Influence of Ag Additive to the Spacer Layer on the Structure and Giant Magnetoresistance of Electrodeposited Co/Cu Multilayers

Application of Surface Roughness Data for the Evaluation of Depth Profile Measurements of Nanoscale Multilayers

Electron‐Impact (EI) Secondary Neutral Mass Spectrometry (SNMS)

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