The effect of surfactants on the growth of Co/Cu multilayers

Marszałek, M.; Polit, A.; Tokman, V.; Zabila, Y.; Protsenko, І. Yu.

doi:10.1016/j.susc.2007.04.216

Cited by 12 publications

(13 citation statements)

References 14 publications

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“…Several other surfactant elements such as Bi, [26][27][28][29][30] Ag, [31][32][33][34][35] Au 36 and In 37 have been similarly found to induce layer quality improvement for physically deposited multilayers.…”

Section: D332mentioning

confidence: 99%

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: D332mentioning

confidence: 99%

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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“…low surface energy metals like Bi or Pb, to the films. The addition of a small amount of surfactant into the Co/Cu multilayered system significantly reduces the degree of interfacial roughness [3]. The results showing the correlation between structural and magnetic properties of surfactant mediated Co/Cu multilayers were published elsewhere [4,5].…”

Section: Introductionmentioning

confidence: 74%

AES Studies of Saturation in Surfactant Segregation Process in Co/Cu Multilayers

et al. 2010

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The chemical composition of successive layers in a Co/Cu multilayered system was studied during growth with Auger electron spectroscopy. Experiments were carried out on a sample with 10 repetitions of Co(1 nm)/Cu(2 nm) evaporated at a very low deposition rate in ultrahigh vacuum. A very small amount of Bi or Pb (0.06 nm) was deposited on each Cu film in the system. The experimental data have shown that the concentration of Bi and Pb increases with the number of deposited trilayers up to coverage corresponding to 5 trilayers. At that point the concentration of the surfactant saturated. The changes in the surfactant concentrations are described with a simple model depicting the interaction of the surfactant atoms with the system and how the evolution of the segregation processes. It allows the prediction of the saturation concentration and helps to explain the behaviour of various elements used as a surfactant. The comparison between the theoretical predictions and the experimental results is also discussed.

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“…The structure of multilayers and interface roughnesses were observed using XRR measurements. It is known from the previous studies concerning (Co/Cu/surfactant)×10 multilayers [9] that the application of surfactant causes the smoothing of the layers in comparison with the reference sample, and additionally the interface roughness is smaller when Bi is used. In Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In the previous work [9] it was shown that the surfactants, evaporated at each Cu layer of Co/Cu system, segregate to the surface during the deposition process, leading to a reduction of an interface roughnesses. The aim of the present work is to study in details the mechanism of the segregation process as a function of the thickness of Co/Cu layers deposited on top of it, and to analyze the interface quality of the multilayers.…”

Section: Introductionmentioning

confidence: 99%

The Behaviour of Surfactants during the Growth of Co/Cu Multilayers

et al. 2007

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The [Co(1 nm)/Cu(2 nm)] N multilayers with different numbers of bilayer repetitions (N = 3 and 10) were thermally evaporated on Si(100) substrates with a small amount of Bi or Pb deposited only on the first and on the second Cu layer. The chemical composition of the surface after each step of the preparation process was studied by Auger electron spectroscopy. The evolution of the Auger peaks showed the segregation of Bi and Pb surfactants. During the evaporation of the subsequent Co and Cu layers, gradual decrease in the surfactant amount on the surface was observed. No appearance of Co peak on the Cu layer, and Cu peak on the Co layer even for a coverage of a fewÅ indicates the layer continuity. The interface roughness of the surfactant-mediated Co/Cu layers analyzed by X-ray reflectometry (when surfactant was deposited twice) was similar to the pure Co/Cu samples. However, more repetitions of surfactant, by reduction of interface roughness, improve the layer quality.

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The effect of surfactants on the growth of Co/Cu multilayers

Cited by 12 publications

References 14 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

AES Studies of Saturation in Surfactant Segregation Process in Co/Cu Multilayers

The Behaviour of Surfactants during the Growth of Co/Cu Multilayers

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