Characterization of Co-Al-O magnetic thin films by combined use of XPS, XRD and EPMA

Asami, K.; Mitani, Seiji; Fujimori, H.; Ohnuma, S.; Masumoto, T.

doi:10.1002/(sici)1096-9918(199908)28:1<250::aid-sia587>3.0.co;2-t

Cited by 15 publications

(6 citation statements)

References 14 publications

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“…In order to resolve those issues and obtain optimal soft magnetic properties, knowledge of the nanostructure of the film is required. In previous studies of nanogranular films, a possible intermixing of magnetic elements into the amorphous matrix was often noted [7][8][9][10]. A magnetic element dispersed in the matrix can influence the magnetic properties via a reduction of magnetization, a modulation of magnetic coupling, and/or a change in transport properties [11].…”

Section: Introductionmentioning

confidence: 99%

Nanostructure characterization of Co–Pd–Si–O soft magnetic nanogranular film using small-angle X-ray and neutronscattering

Oba

Ohnuma

et al. 2013

Journal of Magnetism and Magnetic Materials

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The nanostructure of a Co-Pd-Si-O nanogranular film was investigated with the combined use of small-angle x-ray (SAXS) and neutron scattering (SANS). Using a new, compact type of SANS instrument, the SANS profiles of individual particles with a diameter of about 2-4 nm were successfully observed. The structures of magnetic regions were found to be the same as the chemical structures of the particles, and a sharp interface was observed between the matrix and the particles. The SAXS to SANS ratio clearly indicates that the particles are a CoPd alloy and the matrix is not pure SiO 2. In fact, the matrix is composed of a meaningful amount of Co.

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Section: Introductionmentioning

confidence: 99%

Nanostructure characterization of Co–Pd–Si–O soft magnetic nanogranular film using small-angle X-ray and neutronscattering

Oba

Ohnuma

et al. 2013

Journal of Magnetism and Magnetic Materials

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“…The high-resolution Co 2p and V 2p XPS spectra are shown in Figure 4, and the Co 2p 3/2 electron binding energy (Figure 4a) is 781.78 eV, corresponding to the Co +2 state, indicating the cobalt oxide (CoO) formation. 39 The oxidation of metal nanoclusters during XPS sampling procedure is a known phenomenon, 38 as there is no indication of CoO formation in the XRD. Additionally, the absence of any metal oxides peak in the Raman spectrum of VCKB also confirmed that metal oxide is formed only during the XPS sampling procedure, as Raman is a strong tool to test the existence of CoO.…”

Section: Resultsmentioning

confidence: 99%

“…The XPS was used for examining the composites′ surface configuration and chemical valence. The high-resolution Co 2p and V 2p XPS spectra are shown in Figure , and the Co 2p 3/2 electron binding energy (Figure a) is 781.78 eV, corresponding to the Co +2 state, indicating the cobalt oxide (CoO) formation . The oxidation of metal nanoclusters during XPS sampling procedure is a known phenomenon, as there is no indication of CoO formation in the XRD.…”

Section: Resultsmentioning

confidence: 99%

Atomic V- and Co-Modified Ketjen Black–Sulfur Composite for High-Performance Lithium–Sulfur Batteries

Fazal

Eroğlu

Kilic

et al. 2023

ACS Appl. Energy Mater.

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In the present study, we encapsulated sulfur with atomic vanadium (V)- and cobalt (Co)-modified Ketjen black (VCKBS) to hinder the shuttle mechanism and enhance the redox kinetics in Li–S batteries. The synthesized composite provided plenty of interfacial active sites and assured smooth electron transfer, which assisted in attaining the balance of the enhanced catalytic activity due to Co and the adsorption ability mainly derived from V. Consequently, the Li–S cells having an optimized composition presented alleviated shuttle effect, enhanced sulfur utilization and conversion efficiency, and showed stable cycling performance and an outstanding rate performance with an initial capacity of 1329 mAh g–1, which was maintained as 1249 mAh g–1 after 100 cycles. Due to impressive experimental specific capacities, the system-level specific energies and energy densities were also predicted using the 1st and 100th discharge capacities. Compared to regular Ketjen black-based cathodes, VCKBS cathodes showed 1342 and 568% improvement in the system-level energy density and specific energy based on the 100th discharge capacities, respectively. This indicates that VCKBS cathodes synthesized in a facile manner are advantageous for higher sulfur loadings at electrolyte-depleted cells and represent a viable endeavor to develop highly stable Li–S batteries.

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“…18,20 The O 1s peak for Al-O bonding is at 531.6 eV, while the Co-O bonding peak is 530.4 eV for the fits. 21 However, as shown in background. The magnetic moment of the granules, however reduces in magnitude (by 25%) as shown in Fig.…”

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confidence: 91%

“…18,20 The O 1s peak for Al-O bonding is at 531.6 eV, while the Co-O bonding peak is 530.4 eV for the fits. 21 However, as shown in Fig 4(b) and (c), the O 1s spectra for both the cases (as deposited and after electric field application) can be fitted very well using a single Voigt function peak at the k-points. These calculations do not include the effects of the curvature, structural defects, and the relaxation which would be inevitably present in the experimental setup.…”

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confidence: 99%

Electric-field-induced magnetization changes in Co/Al2O3granular multilayers

et al. 2013

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We study experimentally the effect of electric field on the magnetization of Co/Al 2 O 3 granular multilayers. We observe two distinct regimes: (a) low-field regime when the net magnetization of the system changes in a reversible way with the applied electric field and (b) high-field regime when the magnetization decreases irreversibly. The former is attributed to the changes in the relative 3d-orbital occupation of the minority and majority bands in the Co granules. A theoretical model has been developed to explain the electric field induced changes in the band structure of the granular system and hence the magnetic moment. The latter result may be understood assuming the electric field induces oxygen migration from Al 2 O 3 to the Co granules, since an increase in oxidation state of the Co granules is shown, through ab-initio calculations, to give rise to a reduced magnetization of the system. 2Electric field control of magnetism has aroused significant interest for future electronics as well as energy efficient magnetic data storage 1 . The effect of electric field on several electronic systems based on magnetic thin films has been demonstrated in the past few years.Application of an external electric field in perpendicular magnetic anisotropy based CoFeB/MgO/CoFeB magnetic tunnel junction aids in lowering the current densities for spin transfer torque switching 2 and for an ultra thin Fe film, the anisotropy direction can be controlled depending on the polarity of the electric field applied across the film. 3 Several theoretical reports also suggest the possibility of changes in the spin density of states at Fe/MgO interfaces in the presence of electric field that can affect both the anisotropy and the net moment of the Fe film. 4, 5Granular magnetic films provide interesting routes for novel physics and device applications by tailoring both the individual and collective properties of the nano-magnets. 6, 7 For example, incorporation of magnetic nanoparticles in the barrier of magnetic tunnel junctions hasbeen theoretically predicted to demonstrate a very high magnetoresistance 8 and higher order tunneling effects have also been experimentally observed in similar systems. 9, 10 In terms of applications, resistive switching is an interesting phenomenon also observed in magnetic granular films. 11,12 However, along with the changes in the resistance of the granular system in the presence of an electric field, the magnetic moment of the granules will also be affected and this has not been investigated either through experiments or theoretical modeling. Another effect of the high electric field can be the migration of the oxygen atoms from the oxide matrix into the Co granules which would affect the magnetization of the granules.In this work, we investigate the effect of electric field on the magnetization of Co granules in the sputter deposited Co/Al 2 O 3 based magnetic granular system. In the low field regime we show systematic and reproducible changes in the net magnetic moment of the system 3 using in-situ ...

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Characterization of Co-Al-O magnetic thin films by combined use of XPS, XRD and EPMA

Cited by 15 publications

References 14 publications

Nanostructure characterization of Co–Pd–Si–O soft magnetic nanogranular film using small-angle X-ray and neutronscattering

Nanostructure characterization of Co–Pd–Si–O soft magnetic nanogranular film using small-angle X-ray and neutronscattering

Atomic V- and Co-Modified Ketjen Black–Sulfur Composite for High-Performance Lithium–Sulfur Batteries

Electric-field-induced magnetization changes in Co/Al2O3granular multilayers

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