Resonant Inversion of Tunneling Magnetoresistance

Resonant tunneling via localized states in the barrier can invert magnetoresistance in magnetic tunnel junctions. Experiments performed on electrodeposited $\mathrm{N}\mathrm{i}/\mathrm{N}\mathrm{i}\mathrm{O}/\mathrm{C}\mathrm{o}$ nanojunctions of area smaller than $0.01\mu {\mathrm{m}}^2$ show that both positive and negative values of magnetoresistance are possible. Calculations based on Landauer-Büttiker theory explain this behavior in terms of disorder-driven statistical variations in magnetoresistance with a finite probability of inversion due to resonant tunneling.