Amorphous iron particles in cosputtered Fe-SiO2 films

Holtz, R.L.; Edelstein, A. S.; Lubitz, P.; Gossett, C.R.

doi:10.1063/1.341297

Cited by 12 publications

(5 citation statements)

References 10 publications

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“…TEM studies have indicated that Fe nanoparticles in the films possess amorphous rather than crystalline structures. The formation of amorphous Fe nanoparticles in asdeposited Fe-SiO 2 films prepared by a co-sputtering method was previously reported by Holtz et al 10 They reported that sputtered films had an excess of silicon; the O:Si atomic ratio was less than 2.0. The excess silicon atoms incorporated into the Fe particles were considered responsible for the amorphous phase of Fe.…”

Section: A Film Composition and Structuresupporting

confidence: 54%

“…The volume fraction of Fe ͓v ͑%͔͒ was then calculated from the atomic Fe:Si ratio using v/(100Ϫv)ϭ0.260(X Fe /X Si ). 10 This relation assumes that the material is completely phase-separated into SiO 2 and crystalline ␣-Fe. On the other hand, Fe nanoparticles have amorphous structures in the present samples, as will become obvious later.…”

Section: A Film Composition and Structurementioning

confidence: 99%

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Ferromagnetic resonance study of diluted Fe nanogranular films

Tomita

Hagiwara

Kashiwagi

et al. 2004

Journal of Applied Physics

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Ferromagnetic resonance ͑FMR͒ in diluted Fe nanogranular films with low volume fractions of Fe (v) has been studied. Films prepared by a co-sputtering technique are composed of amorphous Fe nanoparticles embedded in SiO 2 glass matrices. The resonance of the FMR uniform mode is found to be strongly affected by the v, the temperature, and the angle between the film plane and the applied magnetic field. The present study suggests that the values of these parameters should be carefully selected in order to realize left-handed materials using diluted ferromagnetic-metal nanogranular films.

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Section: A Film Composition and Structuresupporting

confidence: 54%

Section: A Film Composition and Structurementioning

confidence: 99%

Ferromagnetic resonance study of diluted Fe nanogranular films

Tomita

Hagiwara

Kashiwagi

et al. 2004

Journal of Applied Physics

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“…The argument [15] is not very convincing, being based on a specific distortion of a sphere, but there is no way to prove it, one way or the other, except by a direct experiment. The experimental magnetization curve [16] that shows a similarity to the curve discussed here, only with some hysteresis superimposed on it, is inadequate for extrapolating to determine the feasibility of the desirable results.…”

Section: Superparamagnetismmentioning

confidence: 99%

The Special Role of Magnetization Curling in Nanoparticles

Aharoni

2002

phys. stat. sol. (a)

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A qualitative change can occur, in a certain particle size, if the magnetization reverses by the curling mode, as demonstrated by superparamagnetic spheres, and by the initial susceptibility of ideally-soft spheres and disks. The theory of exchange resonance modes in small ferromagnetic spheres is extended to the case of a sphere whose centre is not ferromagnetic, as is the case when the magnetic particle is grown around a non-magnetic nucleus, such as the fine particles of the alloys of Fe, Co, and Ni that are made around a nucleus of a noble metal. A first-order calculation leads to a negligible modification of the eigenvalues for the inner radius used in the experiments. For larger holes, the change can be measurably large for some modes. IntroductionThe theory of micromagnetics has never been able [1] to account for the magnetization processes in bulk ferromagnets. It is commonly believed that these processes are mostly governed by crystalline imperfections in hard materials, and by surface roughness and internal voids in soft materials. Both types help the nucleation of reversed domains on the one hand, and hinder the motion of the walls on the other hand. In both cases, however, the mechanisms are not sufficiently clear, and there is no satisfactory theory for them. There are many numerical simulations, but the results always look as if something is still missing there [2], so that they do not even seem promising yet, and it is not really known how to proceed.The situation is much better with fine ferromagnetic particles, for which it is energetically unfavorable to subdivide into domains, thus eliminating the most difficult theoretical problem of nucleation and growth of reversed domains. Theoretical nucleation fields are [3] close to the experimental coercivities of nearly-perfect whiskers for small whisker radius, but are off by several orders of magnitude for larger radii, thus indicating that the effect of body and surface imperfections is less important in fine particles than it is in larger ones. The computer resources necessary for numerical study of particles, by subdividing them into a sufficiently fine mesh, is also manageable when the particles are not too large. Moreover, there are now several experimental studies of individual particles, with which it should be easy to compare the theoretical results, without the problem of interactions between particles that complicated the analysis of older experiments. And there are some analytic results for ideal particles that can be used as a start and a guidance for the study of less perfect particles.It should thus seem natural for numerical micromagnetics to concentrate on extending the analytic results, by studying the effects of imperfections, and of other phenomena neglected in the old theory, such as surface anisotropy, magnetostriction, etc. For some historical reasons, however, numerical computations have been [2] mostly search-

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“…However, since Fe 2 O 3 has a band gap that typically falls between 1.5 and 2.0 [25][26][27], it is common to utilize Fe-O compounds as a dopant within a transparent matrix, typically SiO 2 [3,5,18,28,29]. While mixtures of silica doped with iron are frequently found in bulk glasses [3,4,8], several methods have been explored for doping iron with silica through sol-gel processes [18,28,30], magnetron sputtering [5,[31][32][33][34][35][36], and chemical vapor deposition [12]. While all of the fabrication methods mentioned are capable of depositing quality films under the proper conditions, the high deposition rates, industrial scalability, and composition control afforded by reactive magnetron co-sputtering [37] make it a prime candidate for deposition of thin films within the Fe-Si-O material system.…”

Section: Introductionmentioning

confidence: 99%

“…While all of the fabrication methods mentioned are capable of depositing quality films under the proper conditions, the high deposition rates, industrial scalability, and composition control afforded by reactive magnetron co-sputtering [37] make it a prime candidate for deposition of thin films within the Fe-Si-O material system. Note that while the majority of the magnetron sputtering related studies focus on maximizing the magnetic properties of metallic Fe within a silica matrix [31][32][33][34][35][36], these studies provide useful insights into processing methods for the Fe-Si-O material system. Given the large emphasis on magnetic properties within the literature, very few systematic studies relating deposition conditions, composition, chemistry, and optical properties, are available.…”

Section: Introductionmentioning

confidence: 99%