Interfacial phenomena related to the fabrication of thin Al oxide tunnel barriers and their thermal evolution

In this work we study phenomena related to the plasma oxidation of thin met allic Al layers, to be used as insulating barriers in magnetic tunnel junct ions. We investigate by barrier impedance scanning microscopy how the barri er's over oxidation influences the local transport characteristics of the o xide layers and the results are correlated with the magnetotransport proper ties of patterned microsized as-deposited and annealed junctions. Interesti ngly, the oxygen reservoir existing at the ferromagnetic metal, degeneratin g the tunnel device, can be utilized for the improvement of the junction's magnetotransport properties by means of thermal annealing processing. (C) 2 001 American Institute of Physics.