44 research outputs found

    Observation of spin-transfer switching in deep submicron-sized and low-resistance magnetic tunnel junctions

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    The spin-transfer effect has been studied in magnetic tunnel junctions (PtMn/CoFe/Ru/CoFe/Al2O3/CoFe/NiFe) with dimensions down to 0.1x0.2 um2 and resistance-area product RA in the range of 0.5-10 Ohm m2 (dR/R=1-20%). Current-induced magnetization switching is observed with a critical current density of about 8e6 A/cm2. The attribution of the switching to the spin-transfer effect is supported by a current-induced dR/R value identical to the one obtained from the R versus H measurements. Furthermore, the critical switching current density has clear dependence on the applied magnetic field, consistent with what has been observed previously in the case of spin-transfer induced switching in metallic multilayer systems

    La parole qui me porte / Paul Valet

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    Table rase / Paul Valet

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    Lacunes / Paul Valet

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    Cation exchange isotherms applied to the study of salt affected-irrigated soils

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    The sodium adsorption ratio (SAR) is usefull to predict the status of waters and soils. It depends on the understanding of ion exchange. This paper shows that the practicle use of isotherm systems on square diagrams makes ion exchange study easier. The experimental curves obtained are expressed with the mathematical model proposed by Laï and Jurinak. It is pointed out that these experimental curves allow a correct representation of parameters involved in exchange process. They also give a theoritical basis to predict cation exchange isotherm at different intermediate concentration. This theory was applied to a "soil-irrigated water" system from Niger. The evolution of SAR could be proceeded when irrigation water was evaporated. (Résumé d'auteur
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