Theory of tunneling magnetoresistance in granular magnetic films

Inoue, Jun–ichiro; Maekawa, Sadamichi

doi:10.1103/physrevb.53.r11927

Cited by 439 publications

(334 citation statements)

References 18 publications

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“…For example, in granular metals, an enhanced tunnel magnetoersistance effect (TMR) effect is measured at low temperatures, in the co-tunneling electrical transport regime [36]. Furthermore, an additional enhancement of the TMR effect is expected in granular metals with high spin-polarization [37], such as granular Heusler compounds.…”

Section: Discussionmentioning

confidence: 99%

Fabrication of FeSi and Fe3Si compounds by electron beam induced mixing of [Fe/Si]2 and [Fe3/Si]2 multilayers grown by focused electron beam induced deposition

Porrati

Sachser

Gazzadi

et al. 2016

Journal of Applied Physics

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Fe-Si binary compounds have been fabricated by focused electron beam induced deposition by the alternating use of iron pentacarbonyl, F e(CO) 5 , and neopentasilane, Si 5 H 12 as precursor gases. The fabrication procedure consisted in preparing multilayer structures which were treated by low-energy electron irradiation and annealing to induce atomic species intermixing. In this way we are able to fabricate F eSi and F e 3 Si binary compounds from [F e/Si] 2 and [F e 3 /Si] 2 multilayers, as shown by transmission electron microscopy investigations. This fabrication procedure is useful to obtain nanostructured binary alloys from precursors which compete for adsorption sites during growth and, therefore, cannot be used simultaneously.

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Section: Discussionmentioning

confidence: 99%

Fabrication of FeSi and Fe3Si compounds by electron beam induced mixing of [Fe/Si]2 and [Fe3/Si]2 multilayers grown by focused electron beam induced deposition

Porrati

Sachser

Gazzadi

et al. 2016

Journal of Applied Physics

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“…The magnetoresistance diminishes for very low and high Co concentrations and vanishes completely when the percolation threshold is reached, as expected. 1 The MR curves, in the superparamagnetic regime, have been fitted to the expression 25 Table III. If the proposed model were to be valid, the magnetoresistance curves corresponding to different temperatures should scale in a unique master curve when plotted as a function of H / T, since the field and temperature dependence enter in Eq.…”

Section: Magnetoresistancementioning

confidence: 99%

“…In contrast, Inoue and Maekawa 25 assume that the tunneling conductance in the dielectric regime can be derived from the classical expression for the spindependent tunneling in FM/I/FM junctions given by Landauer 28 and Maekawa and Gäfvert. 29 24 which was not predicted by any of the two models, and needed the occurrence of higherorder tunneling processes.…”

Section: Introductionmentioning

confidence: 99%

“…[19][20][21][22][23][24] Some results indicate that tunneling magnetoresistance ͑TMR͒ is almost temperature independent in a wide temperature range, in agreement with the Inoue-Maekawa model. 25 However, the relation between magnetism and magnetotransport in granular metals is still an open question, since there are systems showing strong temperature dependence of TMR. 19,26,27 Some of these examples show the distinctive 1 / T decay of TMR of the Helman-Abeles model.…”

Section: Introductionmentioning

confidence: 99%

“…29 24 which was not predicted by any of the two models, and needed the occurrence of higherorder tunneling processes. Granular solids display a broad particle size distribution such that the gross simplification of the Inoue-Maekawa model 25 is not to take into account tunneling between grains of different sizes. Mitani et al 24 extended the model by assuming that the natural consequence of the particle size distribution is the successive onset, as the temperature is decreased, of tunneling processes between large grains through small ones.…”

Section: Introductionmentioning

confidence: 99%

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Tunneling magnetoresistance inCo−ZrO2granular thin films

et al. 2006

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Granular films composed of well defined nanometric Co particles embedded in an insulating ZrO 2 matrix were prepared by pulsed laser depositon in a wide range of Co volume concentrations ͑0.15Ͻ x Ͻ 0.43͒. High-resolution transmission electron microscopy ͑TEM͒ showed very sharp interfaces between the crystalline particles and the amorphous matrix. Narrow particle size distributions were determined from TEM and by fitting the low-field magnetic susceptibility and isothermal magnetization in the paramagnetic regime to a distribution of Langevin functions. The magnetic particle size varies little for Co volume concentrations x Ͻ 0.32 and increases as the percolation limit is approached. The tunneling magnetoresistance ͑TMR͒ was successfully reproduced using the Inoue-Maekawa model. The maximum value of TMR was temperatureindependent within 50-300 K, and largely increased at low T, suggesting the occurrence of higher-order tunneling processes. Consequently, the tunneling conductance and TMR in clean granular metals are dominated by the Coulomb gap and the inherent particle size distribution.

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Magnetic properties of polyvinyl alcohol-based composites containing iron oxide nanoparticles

Godovsky

Varfolomeev

Efremova

et al. 1999

Adv. Mater. Opt. Electron.

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This paper describes the magnetic behaviour of polymer nanocomposites containing nanoparticles (∽10 nm) of maghemite γ‐Fe2O3 and magnetite Fe3O4 in a polyvinyl alcohol matrix. The compositions were synthesised using an original method of in situ preparation, the reaction of oxide formation taking place inside the polymer matrix itself. It is the one‐domain‐per‐particle nature of magnetism in the given polymer nanocomposites that was found to be responsible for such a distinctive feature as superparamagnetism detected using Mössbauer spectroscopy and magnetisation measurements. A giant negative magnetoresistance was found in the highly filled compositions. As far as we know, this is the first time that this effect has been observed in polymer composites based on ferrite nanoparticles. Copyright © 1999 John Wiley & Sons, Ltd.

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Theory of tunneling magnetoresistance in granular magnetic films

Cited by 439 publications

References 18 publications

Fabrication of FeSi and Fe3Si compounds by electron beam induced mixing of [Fe/Si]2 and [Fe3/Si]2 multilayers grown by focused electron beam induced deposition

Fabrication of FeSi and Fe3Si compounds by electron beam induced mixing of [Fe/Si]2 and [Fe3/Si]2 multilayers grown by focused electron beam induced deposition

Tunneling magnetoresistance inCo−ZrO2granular thin films

Magnetic properties of polyvinyl alcohol-based composites containing iron oxide nanoparticles

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