Properties of amorphous Co–Ta and Co–W films deposited by rf sputtering

Naoe, M.; Kazama, H.; Hoshi, Yoichi; Yamanaka, S.

doi:10.1063/1.330217

Cited by 35 publications

(18 citation statements)

References 4 publications

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“…Thus the magnetic moment of Co is reduced by filling its 3d shell with electrons supplied by Ta. A zero Ms with approximately 24-27 at.% Ta was found for sputtered Co-Ta [121][122][123], while 25 at.% Cr is mostly found for sputtered Co-Cr [112]. These data compared with Figs.…”

Section: Saturation Magnetizations For the Co-evaporated Co-ta Filmssupporting

confidence: 63%

Tailoring growth and local composition by oblique-incidence deposition: a review and new experimental data

Kranenburg

Lodder²

1994

Materials Science and Engineering: R: Reports

141

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In this paper features are discussed that are related to the nucleation and growth of thin films deposited by physical vapour deposition. Although the paper is mainly focused on oblique-incidence deposition, a normally-impinging vapour flux will also be described. Two cases of oblique-incidence deposition will be discussed: one obliquely-impinging flux and two obliquely-impinging fluxes from opposite directions. With respect to the microstructure, both similarities and differences between these depositions will be deser~ed. Further, a special feature of two obliquely-impinging vapour fluxes is dealt with, which is the local composition in the lateral direction (parallel to the substrate). The oblique and opposing directions can induce an inhomogeneous chemical composition. This process is referred to as process-induced compositional separation. In addition to reviewing the literature, the paper summarizes experimental data on obliquely co-evaporated Co-Cr, Co-Ag and Co-Ta films. It will be shown from these experimental data that the two vapour directions can be exploited to tailor compositional inhomogeneities.

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Section: Saturation Magnetizations For the Co-evaporated Co-ta Filmssupporting

confidence: 63%

Tailoring growth and local composition by oblique-incidence deposition: a review and new experimental data

Kranenburg

Lodder²

1994

Materials Science and Engineering: R: Reports

141

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“…58 In Co-W alloys, it is ∼ 76 at.% Co, so that those alloys with smaller values have no magnetic moment. 34 In general, for 3d-metal-based alloys, the orientational correlation length of the local magnetic moments has been estimated to be of the order of a few μm. 71 Therefore, in Co-W nanoparticles, with a diameter of the order of a few nanometers, exchange stiffness can maintain local moment correlation within the whole particle, and, thus, yield to a particle net average moment and anisotropy.…”

Section: Discussionmentioning

confidence: 99%

“…34,44 The amorphous forming ability (AFA) of Co-W has been studied in terms of the Miedema's coordinates model Y = | φ/ n 1/3 WS |, where φ = φ Co − φ W , and n WS = n WS (Co) − n WS (W), where φ is the chemical potential, and n WS the electron density of the Wigner-Seitz unit cell, and Z = |(R W − R Co )/R Co |. 44 The Co-X (X = Cr, Mo, W) binary alloy phase space is separated by the empirical law Y = 2.52Z −1/4 in the amorphous and crystalline areas.…”

Section: Morphological Study: Microscopy Measurementsmentioning

confidence: 99%

“…These factors have explained satisfactorily the formation of Co-W amorphous thin films by co-sputtering. 34 In our preparation method, Co nanoparticles are formed first, and a subsequent W capping supplies the alloying metal. The sputtering voltage is enough to let W and Co react, while the substrate temperature avoids crystallization.…”

Section: Morphological Study: Microscopy Measurementsmentioning

confidence: 99%

“…The election of W is based on the known affinity to produce Co-W alloys by sputtering, at room temperature, 17,[31][32][33] on one hand, and the tendency of these alloys to become amorphous. 31,[34][35][36] Besides, short-range structural ordering, observed in films and bulk amorphous alloys, 37,38 has been proposed as the mechanism inducing anisotropy in those systems. So, there was a good chance that Co-W alloying would allow varying the NPs anisotropy as a function of the tungsten concentration, as we prove below.…”

Section: Introductionmentioning

confidence: 99%

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Structural and magnetic properties of amorphous Co-W alloyed nanoparticles

et al. 2011

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W-capped Co nanoparticles dispersed in an alumina matrix are studied by means of high-resolution transmission electron microscopy, extended x-ray absorption fine structure, SQUID-based magnetic measurements, dc magnetization, ac magnetic susceptibility, and x-ray magnetic circular dichroism. Results show the formation of amorphous Co-W alloy nanoparticles, the magnetic properties of which are modified by the amount of W or Co present in the samples. The average Co magnetic moment depends on the number of W atoms surrounding it. Co-W particles show superparamagnetic behavior and are described as an array of noninteracting particles with random anisotropy axes and an average moment per particle proportional to the particle volume and to the average Co moment for each alloy composition. Values of the magnetic anisotropy constant of the particles are on the order of 10 6 erg/cm 3 , higher than that of bulk Co. Evidence of short-range ordering within each amorphous particle is found that provides insight of the origin of their magnetic anisotropy.

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Magnetization and Magnetic Anisotropy of Co/W Multilayers

Spasova

Wiedwald

Ramchal

et al. 2001

phys. stat. sol. (b)

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The magnetic properties of polycrystalline Co/W multilayers have been investigated using angulardependent ferromagnetic resonance (FMR) and SQUID magnetometry. Two sets of samples with a constant thickness of Co layers (CoI: d Co ¼ 1 nm and CoII: d Co ¼ 2.5 nm) and varying W layer thickness (1 to 7 nm) were studied. The structure of the multilayers was analysed by X-ray reflectivity (XRR) and X-ray diffraction (XRD). We found a well-defined h110i texture and coherent structure of the multilayers. The saturation magnetization of Co is smaller than that of bulk Co which is explained by a reduced Co moment at the interfaces of more than 50%. A narrow FMR linewidth on the order of 200 Oe at 9.5 GHz is observed for CoI and CoII multilayers with d W % 1 nm that indicates the high magnetic homogeneity of the Co layers. The second and fourthorder magnetic anisotropy constants (K 2 , K 4? ) are found to be independent of the Co layer thickness. K 2 is inversely proportional to the W layer thickness, which is due to the changing lateral lattice mismatch with the W layers.

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Properties of amorphous Co–Ta and Co–W films deposited by rf sputtering

Abstract: Studies on the thermal release of krypton from rf sputterdeposited amorphous Gd-Co films by a UHV mass spectrometric technique

Cited by 35 publications

References 4 publications

Tailoring growth and local composition by oblique-incidence deposition: a review and new experimental data

Tailoring growth and local composition by oblique-incidence deposition: a review and new experimental data

Structural and magnetic properties of amorphous Co-W alloyed nanoparticles

Magnetization and Magnetic Anisotropy of Co/W Multilayers

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