Surfactant-assisted atomic-level engineering of spin valves

Chopra, Harsh Deep; Yang, David; Chen, P. J.; Egelhoff, William F.

doi:10.1103/physrevb.65.094433

Cited by 20 publications

(16 citation statements)

References 32 publications

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“…It has been demonstrated in the literature that by using surfactants, the problem of asymmetric interfaces can be reduced to a large extent [16][17][18][19][20][21][22]. The prerequisites for a material to qualify as a surfactant is its optimal quantity and a low as compared to other elements present in the multilayer.…”

Section: Introductionmentioning

confidence: 99%

Surfactant controlled interfacial alloying in thermally evaporated Cu/Co multilayers

Amir

Gupta

2012

Journal of Alloys and Compounds

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Section: Introductionmentioning

confidence: 99%

Surfactant controlled interfacial alloying in thermally evaporated Cu/Co multilayers

Amir

Gupta

2012

Journal of Alloys and Compounds

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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%

“…[31][32][33][34] The growth mechanisms induced by Ag as a surfactant in GMR multilayers were investigated by An et al 35 by using interface-sensitive X-ray anomalous scattering techniques. These results also suggested that the addition of Ag during deposition suppresses interfacial intermixing.…”

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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“…[10] Silver has been used a surfactant in the deposition of giant magnetoresistive (GMR) spin valves. [11,12] The GMR spin valve structure generally consists of a magnetic transition metal layer, such as Co, Ni, or Fe, and a layer of a noble metal, such as Au. The transition metals agglomerate as they are deposited on the noble metal layer, unless a surfactant is used.…”

Section: Introductionmentioning

confidence: 99%

“…An order of magnitude increase was reported in the GMR properties of a NiO-Co-Cu-Co structure with the incorporation of silver as a surfactant in the manufacturing process. [12] Generally, depositing elemental materials by ALD is challenging due to the lack of a broadly applicable reducing agent allowing the saturative exchange-type reactions for ALD of compound films. For example, copper deposition has been attempted with several reducing agents, elemental zinc, [13] alcohols, [14,15] and molecular hydrogen, [16][17][18][19][20] but none of them has proven to be a good all-round solution.…”

Section: Introductionmentioning

confidence: 99%

Radical‐Enhanced Atomic Layer Deposition of Silver Thin Films Using Phosphine‐Adducted Silver Carboxylates

Niskanen

Hatanpää

Arstila

et al. 2007

Chemical Vapor Deposition

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Metallic silver films are deposited by radical-enhanced atomic layer deposition (REALD) using (2,2-dimethylpropionato)silver(I)triethylphosphine and hydrogen radicals. The silver precursor used is synthesized in-house, and characterized using CHN elemental analysis, infrared (IR) spectroscopy, nuclear magnetic resonance (NMR), mass spectrometry (MS), and thermogravimetric analysis/single differential thermal analysis (TGA/SDTA). The crystal structure of Ag(O 2 C t Bu)(PEt 3 ) is also solved. Trimeric units are revealed as the building blocks. The hydrogen radicals are produced by dissociating molecular hydrogen with a microwave plasma discharge. The evaporation temperature of the silver precursor is 125°C, and the film deposition temperature is 140°C. The deposition is successful on glass and silicon, and the films are conformal. The saturated growth rate is 0.12 nm per cycle, with a 3 s silver precursor pulse and 5 s hydrogen radical pulse time. The overall cycle time is 14 s. The films are polycrystalline and are visually mirror-like. The films contain 10 at.-% oxygen, 4.0 at.-% phosphorous, 1.0 at.-% carbon, and 5.0 at.-% hydrogen as impurities. Nevertheless, the films exhibit low resistivity, only 6 lX cm for a 40 nm thick film.

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Surfactant-assisted atomic-level engineering of spin valves

Cited by 20 publications

References 32 publications

Surfactant controlled interfacial alloying in thermally evaporated Cu/Co multilayers

Surfactant controlled interfacial alloying in thermally evaporated Cu/Co multilayers

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

Radical‐Enhanced Atomic Layer Deposition of Silver Thin Films Using Phosphine‐Adducted Silver Carboxylates

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