Magnetotransport properties of NiFe-Ag granular alloys: origin of the thermal behavior
MetadataShow full item record
The 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 r M 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 r M vs M2 are discussed. Care should be taken when representing r M /r(T,H50) 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 r(T,H50) 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.
Is part ofJournal of Applied Physics, 1997, vol. 82, núm. 2, p. 677-687
European research projects
Showing items related by title, author, creator and subject.
Impact of the self-adaptive valve behavior on an array of microfluidic cells under unsteady and non-uniform heat load distributions Laguna Benet, Gerard; Vilarrubí, Montse; Ibáñez, Manuel; Rosell Urrutia, Joan Ignasi; Badia Pascual, Ferran; Azarkish, Hassan; Collin, Louis-Michel; Fréchette, L. G.; Barrau, Jérôme (Regional Information Center for Science and Technology, 2019)Previous studies have demonstrated that the performance of a cooling scheme based on a matrix of microfluidic cells with self-adaptive valves under unsteady and non-uniform heat load scenarios improves in terms of pumping ...
Badia Pascual, Ferran; Badry, M. A.; Zhang, X. X.; Tejada, J.; Brand, R. A.; Scholz, B.; Keune, W. (American Institute of Physics, 1991)Multilayered Fe/Tb samples were prepared under ultrahigh vacuum conditions (p<10−9 mbar) on kapton substrates. A total of four different samples were prepared. Three of them correspond to a series where the Tb thickness ...
Barrau, Jérôme; Ibáñez, Manuel; Badia Pascual, Ferran (Elsevier, 2014)From the sustainable perspective, the optimum thickness calculations of the buildings envelope insula-tion materials published in scientific journals suffer a number of notable shortcomings. The most relevantare the short ...