Low-resistance magnetic tunnel junctions with an Mg O − Al 2 O 3 composite tunnel barrier: Asymmetric transport characteristics and free electron modeling of a self-limited oxidation bilayer
Résumé
Low-resistance magnetic tunnel junctions with an MgO-Al$_2$O$_3$ composite tunnel barrier have been grown. From the theoretical point of view, current-voltage and magnetoresistance-voltage characteristics are predicted to be asymmetric. These asymmetries are studied as a function of barrier thicknesses for given experimental MgO and Al2O3 barrier heights. From an experimental point of view, the bottom alumina barrier acts as a diffusion barrier allowing the complete oxidation of the thin deposited Mg layer. As a result, composite Al$_2$O$_3$/MgO tunnel barriers show a lower area resistance and a magnetoresistance signal at nonzero applied voltage that is predicted to be equivalent as single Al$_2$O$_3$ tunnel barriers with the same total thickness. Current-voltage and magnetoresistance-voltage characteristics are shown to be asymmetric at high voltages.
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Low-resistance magnetic tunnel junctions with an alumina - magnesium oxide composite tunnel barrier self limited oxidation material, asymmetric transport characteristics and free electron modelling-de_Buttet_PRB_06.pdf (244.12 Ko)
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