Bi surfactant effects of Co/Cu multilayered films prepared by sputter deposition

Kamiko, Masao; Nakamura, Atsuhito; Aotani, Kazuaki; Yamamoto, Ryōichi

doi:10.1016/j.apsusc.2009.05.081

Cited by 7 publications

(3 citation statements)

References 17 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%

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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: D332mentioning

confidence: 99%

“…Further studies [23][24][25][26][27] have also demonstrated the beneficial effect of Pb as surfactant in evaporated and MBE-grown FM/NM multilayers. 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.…”

mentioning

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.

View full text Add to dashboard Cite

show abstract

“…However, the effect of surfactants on the growth of Co/Cu structures by magnetron sputtering is still little studied and sometimes leads to contradictory results. In particular, the roughness at the boundaries could be increased, but at the same time the magnetic characteristics could be improved due to the more ordered direction of crystallization [28]. The hybrid method for analyzing layered structures presented in this work can be highly effective not only for determining the profiles of the main elements, but also for studying the behavior of surfactant atoms.…”

Section: Analysis Of Obtained Atomic Profiles and Discussionmentioning

confidence: 98%