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dc.contributor.authorBadia, Ferrancat
dc.contributor.authorBatlle Gelabert, Xaviercat
dc.contributor.authorLabarta, Amílcarcat
dc.contributor.authorWatson, M.
dc.contributor.authorJohnston, A.
dc.contributor.authorChapman, J.
dc.description.abstractThe effect of the temperature and magnetic field on the giant magnetoresistivity (GMR) of two FeNi–Ag granular alloys of composition Fe11.4Ni6.4Ag82.2 and Fe7.6Ni16.4Ag76.0 is discussed. Both samples were prepared by rf magnetron sputtering. Parts of them were rapidly annealed at 600, 650, and 750 °C. All samples displayed giant magnetoresistivity which decays from its maximum value with a Tm behavior, with m≈0.8–0.9, suggesting that the decrease in the maximum magnetoresistivity is due to the reduction in the particle magnetization associated with the spin wave excitation, which is a different mechanism to the electron-magnon interaction responsible for the T dependence of GMR in magnetic multilayers. Magnetoresistivity ρM decreases with temperature sharing essentially the same temperature decrease as the square of the macroscopic magnetization M in the whole magnetic field range studied, which is due to the reduction in the particle magnetization and to superparamagnetic effects. The effect of the width of the particle size distribution and interparticle interactions on the linear relation ρM vs M2 are discussed. Care should be taken when representing ρM/ρ(T,H=0) vs (M/Ms)2 because the strong temperature-dependent slope shown in these plots is mainly due to the temperature dependence of both the resistivity ρ(T,H=0) and Ms, and it is not an intrinsic T dependence of GMR in granular alloys. Experimental results suggest that in granular materials, magnetoresistivity is dominated by magnetic moments at the surface of the particles, which also play a very important role in the demagnetization processes, and small magnetic particles.-
dc.format.extent11 p.-
dc.publisherAmerican Institute of Physics-
dc.relation.isformatofReproducció del document publicat a:
dc.relation.ispartofJournal of Applied Physics, 1997, vol. 82, núm. 2, p. 677-687-
dc.rights(c) American Institute of Physics, 1997-
dc.subject.classificationCamps magnèticscat
dc.subject.classificationPropietats magnètiquescat
dc.subject.classificationMetalls de transiciócat
dc.subject.classificationMatèria condensadacat
dc.subject.otherMagnetic fieldseng
dc.subject.otherMagnetic propertieseng
dc.subject.otherTransition metalseng
dc.subject.otherCondensed mattereng
dc.titleMagnetotransport properties of NiFe-Ag granular alloys: origin of the thermal behavioureng
Appears in Collections:Articles publicats en revistes (Física de la Matèria Condensada)

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