The effect of interactions on electron tunnelling via exchange scattering

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Abstract
The effect of interactions between the magnetic moments which exchange scatter tunnelling electrons is to depress the conductance below the logarithmic temperature and voltage behaviour which is found for junctions with low concentrations of magnetic moments. Interactions make the scattering inelastic and this curtails some of the processes, in a similar way that an external field does. The interactions are replaced by a distribution of internal fields and the effect of interactions found using both theoretical and measured values of G(V,H,T). The results are qualitatively similar and show that the effect of interactions can make G(V) independent of V for eV H where TH is a temperature that characterizes the strength of the interactions. At higher concentrations of magnetic moments or at lower temperatures G(V) has a minimum at V=0. The temperature dependence of G(V=0) shows a maximum which shifts from T=0 to T approximately TH in the presence of interactions. Such behaviour has recently been found in Ti doped Al/Al oxide/Ag junctions.