Modeling field dependence of giant magnetoresistance in ‘‘granular’’ and quasi-granular magnetic films

Parker, M.R.; Barnard, J. A.; Seale, D.; Waknis, A.

doi:10.1063/1.353686

Cited by 34 publications

(6 citation statements)

References 3 publications

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“…According to this model the quantitative treatment of the positive magnetoconductivity of the Fe-doped films has to include an internal magnetic field and the alignment of local magnetic moments. The appropriate ansatz should be an approximation of the squared Langevin-like function in analogy to the treatment of the giant magnetoresistance ͑GMR͒ in heterogeneous systems, 29 ⌬͑B ͒ϭaϫ͓B 2 /͑B 2 ϩB 0 2 ͔͒. ͑6͒…”

mentioning

confidence: 99%

Electrical and magnetoconductivity of binary and Fe-dopeda−RexSi1−xthin films ne

et al. 2003

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The low-temperature electrical transport behavior of amorphous Re x Si 1Ϫx and Re x Fe y Si 1ϪxϪy thin films has been investigated as a function of temperature and magnetic field on the metallic side of the metal-insulator transition ͑MIT͒. In the temperature range above 20 K both undoped and Fe-doped films show the same approximately linear behavior of conductivity up to 300 K. At temperatures below 20 K the conductivity of the Re x Si 1Ϫx system can be understood on the basis of the theory of quantum corrections to the conductivity: The temperature dependence of the conductivity and the negative magnetoconductivity are caused by electronelectron interactions. The conductivity of Fe-doped films shows a completely different behavior. The comparison of undoped and Fe-doped films at the same ͑0͒ demonstrates that the width of the density of states anomaly near the Fermi energy ⌬ differs by two orders of magnitude. The positive contribution to the magnetoconductivity increasing strongly with decreasing temperature can be explained within a model of bound magnetic polarons and is related to additional spin scattering.

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confidence: 99%

Electrical and magnetoconductivity of binary and Fe-dopeda−RexSi1−xthin films ne

et al. 2003

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“…Above this value, the decrease of the GMR is observed indicating a change in the magnetic behavior regime from superparamagnetic to magnetically ordered state (because several particles act together). From the fits of the magnetoresistance curves versus temperature (T ) and field (H) using a Langevin function L(x) with x = V MsH kT , where V is the grain volume and M s the saturation magnetization, we can estimate the particles size [7]. In the superparamagnetic state, the development of this function can be limited leading to L(x) ∼ = x in a first approximation.…”

Section: Magnetic and Transport Propertiesmentioning

confidence: 99%

“…In the superparamagnetic state, the development of this function can be limited leading to L(x) ∼ = x in a first approximation. In this case, the size of the magnetic grains can be deduced from the GMR curves versus the applied magnetic field H [7] (see Fig. 4b).…”

Section: Magnetic and Transport Propertiesmentioning

confidence: 99%

Magnetic interactions in transition metal clusters embedded in matrices prepared by LECBD technique

Dupuis

Tuaillon

Prével

et al. 1997

Z Phys D - Atoms, Molecules and Clusters

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The synthesis of iron and cobalt clusters embedded in an insulating or metallic matrix have been realized by the co-deposition of both beams arriving at the same time on a 45 • -tilted substrate. The nanoparticles were produced from an intense cluster beam of selected size (centered around 300 atoms per cluster) produced from a laser vaporization source. We used a Knudsen cell to evaporate the matrix. From the ratio of the deposition rates of both beams, we were able to adjust continuously the atomic concentration of clusters in the matrix from 3 to 70 %. The typical size distribution of embedded clusters determined from HRTEM observations on diluted samples revealed nanocrystallizedgrains with a very narrow size dispersion. Moreover, magnetoresistance (MR) and magnetization measurements versus temperature and concentration were performed. The results show clearly a magnetic threshold around 25 % Co-clusters content in matrix, corresponding to the transition from superparamagnetic to magnetically ordered state. This threshold is identical to the 3D-percolation threshold for connected particles. A maximum of MR ratio of 12 % at 4.2 K was obtained for Co 25% Ag 75% granular film at the onset of non negligible magnetic interactions between Co-particles. The magnetic properties of our systems, strongly correlated to the nucleation processes, allowed us to determine the variation of the cluster radius as a function of the concentration and of the matrix nature.

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“…However MR in bulk nano-crystalline Co-Ag has not been explored yet. For a sizable GMR, small particles are favorable because of the large surface/volume ratio [6][7][8][9]. The size of the particles and their separation must be smaller than the spin-dependent electron mean free path [10].…”

Section: Introductionmentioning

confidence: 99%

Magneto-resistance above 300K in nano-crystalline Co–Ag metastable solid solutions

Srivastava

Manoharan

2008

Journal of Magnetism and Magnetic Materials

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Modeling field dependence of giant magnetoresistance in ‘‘granular’’ and quasi-granular magnetic films

Cited by 34 publications

References 3 publications

Electrical and magnetoconductivity of binary and Fe-dopeda−RexSi1−xthin films ne

Electrical and magnetoconductivity of binary and Fe-dopeda−RexSi1−xthin films ne

Magnetic interactions in transition metal clusters embedded in matrices prepared by LECBD technique

Magneto-resistance above 300K in nano-crystalline Co–Ag metastable solid solutions

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